COMPASS for Windows

Training Manual
Version 1998.7
copyright © 2000 by Landmark Graphics Corporation

Part No. 157605, Rev. 1998.7 August 30th, 2000

Copyright
Copyright © 2000 by Landmark Graphics Corporation
All rights reserved worldwide. Printed in USA.

Publication Notice
This publication has been provided pursuant to an agreement containing restrictions on its use.
The publication is also protected by Federal copyright law. No part of this publication may be
copied or distributed, transmitted, transcribed, stored in a retrieval system, or translated into any
human or computer language, in any form or by any means, electronic, magnetic, manual, or
otherwise, or disclosed to third parties without the express written permission of Landmark
Graphics Corporation (15150 Memorial Drive, Houston, TX 77079 U.S.A.).

Trademark Notice
COMPASS is a trademark of Landmark Graphics.Microsoft, MS-DOS, Access, ODBC,
Windows, Windows for Workgroups, Windows NT, and Windows 95 are registered trademarks
of Microsoft Corporation. dBASE is a registered trademark of Borland Corporation.Other brand
or product names are trademarks or registered trademarks of their respective holders.

Information Change Notice

The information contained in this document is subject to change without notice and should not be
construed as a commitment by Landmark Graphics Corporation. Landmark Graphics
Corporation assumes no responsibility for any error that may appear in this manual. Some states
or jurisdictions do not allow disclaimer of expressed or implied warranties in certain
transactions; therefore, this statement may not apply to you.

ii COMPASS for Windows Training ManualLandmark

COMPASS for Windows Support

Customer support can be reached at the following phone numbers:

North America
Telephone: 281-560-1200 or toll free 1-877-HELP-LGC
Email: support@lgc.com

South America
Telephone: 582-952-7691
Email: ven_soporte@lgc.com

Europe, Africa, Middle East - business hour support only: 8 a.m. - 6 p.m.
Local Time, Monday - Friday, excluding holidays.
Telephone: +44 1224 778500
Email: pc-support-aberdeen@lgc.com

Asia, Pacific
Telephone: +61 89482 4140

Web site - Landmark maintains a web site at www.lgc.com.

FTP site - Landmark Graphics maintains an FTP site at FTP.lgc.com. This site contains updates
and executables that can be downloaded. In addition, data can be uploaded to the site.

Landmark COMPASS for Windows Training Manual iii

 Contents

Contents
COMPASS for Windows Support . . . . . . . . . . . . . . . . . . . . . iii
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
Origins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
About This Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
System Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
Planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
Anti-Collision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
Roles and Workflows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Single User and Network Installations . . . . . . . . . . . . . . . . . . . . . . . 1-8
Introducing Directional Drilling . . . . . . . . . . . . . . . . . . . . . . 2-1
Origins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Early Means of Directional Control . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
Modern Directional Drilling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
Mud Motor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
Measurement Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9
Measurement While Drilling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11
Emerging Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13
Coiled Tubing/Under Balanced Drilling . . . . . . . . . . . . . . . . . . 2-13
Multi-Laterals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-14
Rotary Steerable Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-16
Geo-Steering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-18
Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
Starting COMPASS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
Application Layout Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
COMPASS Menu Bar. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
Toolbar Icons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
Status Bar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8
Status Window and Browser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8
Using the Online Help . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10
Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11
Databases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13
Changing Databases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-14
Network Terminology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-14
Client/Server Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-14
Data Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
Company. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
Company Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
Defaults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11
Company Wellpath Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-16

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Contents

Company Survey Tool Editor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-17

Survey Tool Error Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-21
Field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-29
Field Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-30
Site Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-36
Error Surface Origin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-39
Well . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-46
Well Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-46
Wellpath . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-49
Wellpath Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-50
Surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-54
Plans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-54
Definitive Path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-55
Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
Site Editors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
Site Template Editor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
Site Datum Table Editor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5
Targets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7
Target Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-18
Target Viewer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-22
Wellpath Editors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-23
Survey Program Editor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-23
Wellpath Casing Editor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-29
Wellpath Formation Editor . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-31
Lithology Editor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-32
Wellpath Annotation Editor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-35
Graphics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-36
Customising Live Graphs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-37
Graph Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-37
Geodetic Calculator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-42
The Calculator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-42
Geodesy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-43
Geomagnetism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-48
Graphic Offset Wells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-52
Import/Export . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-53
Compass Transfer Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-54
Import DOS COMPASS Data . . . . . . . . . . . . . . . . . . . . . . . . . . 5-57
Wellbore Planner Import / Export . . . . . . . . . . . . . . . . . . . . . . . 5-59
DIMS for Windows Survey Import . . . . . . . . . . . . . . . . . . . . . . 5-60
Data Exchange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-61
Survey Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
Survey Setup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2
Tie-on Point Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4
Survey Import . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5
Survey Data Editor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-10

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 Contents

Interpolation Window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-11

Project Ahead . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-12
Input Validation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-20
Varying Curvature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-21
Survey Data Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-24
Survey Reports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-29
Survey Export . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-34
Planning Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1
Plan Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1
Plan Editor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5
Planning Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-10
2D Directional Well Planning . . . . . . . . . . . . . . . . . . . . . . . . . . 7-11
3D Well Planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-14
Incremental Measured Depths . . . . . . . . . . . . . . . . . . . . . . . . . . 7-24
Wellpath Optimiser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-31
Additional Plans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-51
Planning and Anti-Collision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-51
Planning Reports. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-52
Create a New Custom Report . . . . . . . . . . . . . . . . . . . . . . . . . . 7-56
Redesign an Existing Custom Plan Report . . . . . . . . . . . . . . . . 7-57
Delete Report Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-57
Planned Wellpath Export . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-57
Anti-Collision Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1
Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-2
Error System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-2
Scan Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-8
Warning Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-13
Error Surface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-15
Anti-Collision Scan Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-18
Anti-Collision Offset Wells . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-18
Interpolation Interval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-22
Result Graphics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-25
Ladder View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-29
Optionally . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-29
Ratio Factor View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-33
Travelling Cylinder View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-35
3D Proximity View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-42
Reports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-44
Anti-Collision Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-45
Error Ellipse Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-48
Site Optimiser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1
Site Optimiser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-2

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Wallplot Composer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1
Page Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-2
Graph Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-2
Wall Plot Composer Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-13
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-1

viii COMPASS for Windows Training Manual Landmark

 Chapter 1: Introduction

Introduction

Computerized Planning and Analysis Survey System (COMPASS) is a

suite of software tools for well survey management, directional well
planning, and collision avoidance that has strong links with other
Landmark drilling engineering, and geoscience applications.

COMPASS enables you to

• Design the shape of wellbores using the PLANNING Module.

• Calculate the shape of wellbores using the SURVEY Module.
• Calculate positional uncertainty and wellbore separation using the
ANTI-COLLISION Module.
• Create hardcopy plots using the WALLPLOT COMPOSER
Module.
• Display results using various online graphics and hardcopy reports.
• Construct a data repository for storing deviation data that can be
linked to other data models.

Origins
COMPASS is a fusion of the best ideas from Jamieson Technical
Software’s original DOS COMPASS program, DRD’s Wellpath
software, and Munro Garrett’s Target software. Landmark’s acquisition
of these products enabled the COMPASS software development group
to build on the strength of these three products when developing the
original 16-bit Windows version available since 1995. From 1999,
COMPASS has been commercially available as a 32-bit Windows
application.

About This Manual

This training manual complements the instruction provided in the
COMPASS for Windows 2 day training course, and each section
corresponds with sessions completed during the course. This manual
can be used both during and after the course to answer questions you
have about COMPASS.

It is assumed that you are knowledgeable about directional drilling,

surveying, well planning and anti-collision.

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Chapter 1: Introduction

System Overview
COMPASS is designed to increase the efficiency and cost-effectiveness
of directional well planning and wellbore monitoring by providing an
easy to use interface and numerous other features. COMPASS enables
fast and accurate well planning and identification of potential directional
drilling problems at the earliest possible stage.

COMPASS is designed for oil companies, well planners, and directional

contractors, and enables an engineer to track a well through the
following stages:

• The initial data gathering stage determining required geological

targets, surface drilling locations, planning constraints.
• The various phases of directional well design including collision
avoidance, target analysis, operational stages of recording surveys,
checking for anti-collision risks, doing look-aheads, and
performing survey quality assessments.
• The compilation of a final definitive survey.
The following range of technical features ensure that COMPASS is the
most comprehensive software of its kind available today:

• ODBC-compliant databases (Sybase SQL Anywhere, Oracle,

Microsoft SQL Server, Sybase RDBMS)
• A logical, context-designed data model
• A consistent easy-to-use interface
• Flexible units handling
• Comprehensive, context sensitive online help written by engineers
• Comprehensive live graphical output
• Multi-component, customizeable plots with Wallplot Composer
• Formatted customizeable reports with ASCII file options
• Integrated planning and analysis work flow complemented by live
graphic updates
• Support for multiple depth datums per site
• Integration with industry accepted Geodetic, Geomagnetic, and
Survey Tool Error models
• Customizeable survey tool error models
• Definition of targets with different geometry types
• Project Ahead and Varying Curvature Survey Analysis tools

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 Chapter 1: Introduction

• An easy-to-use planning tool with numerous 2D and 3D planning

solutions
• Improved horizontal well support with multiple target threading
• Curved Conductor/Slant rig support with configurable well
reference point.
• Multiple Anti-Collision Scan Methods and Graphical Outputs
• Detailed Positional Uncertainty Error Surface Geometry calculation
and reporting
• Integration with other Landmark software products such as
Wellplan, DIMS for Windows, StressCheck, CasingSeat, WellCat,
DrillModel and Landmark’s OpenWorks applications including
Wellbore Planner
• An easy-to-use export routine that enables data sharing with other
disciplines and applications

Modules
COMPASS consists of 3 main modules integrated by a host of
supporting features and an underlying data structure.

Survey
The Survey module calculates a Wellpath’s actual trajectory. Within
COMPASS, a Survey is a set of observations made with the same survey
tool over the same tool run. Typically, this is a survey tool run in a
certain sized hole section such as 12-1/4” MWD, 9-5/8” Gyro.

After you select a survey calculation method and surveying tool, you
can enter survey observations directly, import them from a file, or paste
them from the Windows clipboard.

The survey module supports the following 3 types of data:

• Standard MD, Inc. & Azi.

• Inertial TVD, N & E
• Inclination only MD & Inc.
From the Survey’s tie-on point, the survey editor automatically
calculates the wellpath trajectory and error surface geometry that
describes the positional uncertainty over the survey.

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Chapter 1: Introduction

After you enter data, you can do the following:

• Perform point interpolations for any number of Measured or True

Vertical Depths, Inclination or Azimuths.
• Use the Project Ahead tool to compare the wellpath’s current
trajectory against a proposed target or plan.
• Perform Free Projections to a proposed MD or TVD using an
entered Build & Turn rate, Dogleg & Toolface, or by constructing a
trend using a number of existing survey observations.
Two methods, Input Validation and Varying Curvature, enable you to
assess survey data for incorrectly entered survey data or bad readings
from the survey tool. Analysis Graphs are available that produce
comparison plots of survey and plan data for a number of different
variables.

You can share COMPASS survey data that can be referenced to any
number of user-defined datums and can include a number of optional
data sections. Survey data can be output by printing from a number of
canned or custom formatted report layouts that you can send to an
ASCII file. You can also export survey data to a raw survey file or
output it to a number of canned or custom export file formats. The
COMPASS data model can also be shared with other application data
model using views.

Once a survey is saved, you can include it in the Definitive Wellpath,

which is the most accurate estimate of actual wellpath trajectory.

Planning
You use the Plan Editor to design the shape of proposed wellbores. It
consists of numerous mathematical solutions with built-in dynamic
links to the Target Editor and the Anti-Collision module, enabling all 3
tools to be used concurrently. Based on a Plan’s tie-on point, you can
construct 2D & 3D plans by entering points in space or specifying a link
to a Geologic or Drilling target. The target adjust feature allows a plan
to be landed in locations you select about the target horizontally and
vertically.

Different plan methods are supported:

• Slant Well and S-Well designs are available to plan a well within a
vertical section.

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• In 3D, you can construct plans using Build & Turn curves for
rotary-drilled sections or Dogleg/Toolface curves for steering tool-
drilled sections.
• You can also use additional tools like Optimum Align, which
enables steering to be minimized to certain user selected parts of
the well, Thread Targets, which automatically constructs a plan
through 2 or more targets using various plan types, and the Landing
Calculator, which enables a plan to intersect a target plane along a
given azimuth.
• For long hold sections, a plan can be corrected for anticipated Walk
Rates through certain formations.
The Wellpath Optimizer is a tool that enables you to optimize a planned
wellpath trajectory for mechanical conditions. Using a soft string
torque/drag model, the software calculates mechanical profiles for a
range of plans based on ranges of parameters you enter such as DLS or
KOP depth. You can compare different plans based on their entered
ranges. Additionally, the Wellpath Optimizer can calculate the best
overall well trajectory to reduce mechanical limitations.

Plans are presented in a grid with rows for each section in the plan. You
can edit grid cells directly to edit plan sections. Alternatively, parameter
fields underneath the grid enable you to modify the plan. Like Surveys,
you can view Plans using all available graph types. Additionally, you
can highlight each section in the plan grid using the graphs. Planning
reports enable you to send plan details to other parties. Report options
allow you to output the plan referenced to other datums for use by other
disciplines.

Anti-Collision
You can use the Anti-Collision module to check the separation of
surveyed and planned wellpaths against any number of offset wells. The
module consists of 3 calculations: Wellpath Separation and Positional
Uncertainty linked by Ratio Factor or Risk Based rules.

Based on Company preferences or collision avoidance policy, you can

configure an anti–collision scan at different levels, monitor all or parts
of the current wellpath, and report to different collision criteria. Anti-
collision results are available in graphical format or in reports.

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The following graphs are available:

This graph.... Depicts this...

Spider Plot Plan View of all wellpaths included in scan.

Ladder View MD against wellpath separation.

Ratio Factor View MD against Ratio Factor.

Travelling Cylinder View Wellpath separation referenced from either

High side of well or High Side + current Well
Azimuth.

3D Proximity View 3D presentation of all wells included in scan.

Reports consist of:

• A Summary report that details wellpath positions close to the

reference wellpath
• An Error Ellipse report that describes the geometry of the
uncertainty ellipsoid at all depths down the reference wellpath

Roles and Workflows

COMPASS is designed for engineers with different responsibilities and
for different types of organizations such as Oil Companies, Directional/
Survey Contractors, and Engineering Consultants. Different users use
COMPASS in different ways and work with different modules within
COMPASS according to their jobs.

Within an Oil Company, a Well Planner plans a well to intersect one or

more targets provided by their Geoscience department. Targets are
analysed and sized in conjunction with the design of the survey
program. The plan may be 2D or 3D and may require the use of rotary
or steerable bottom hole assemblies for it to be drilled. The plan is
communicated to and agreed upon by all concerned parties.

While drilling, the Rigsite Company Representative uses COMPASS to

enter and collate Survey data, report the Wellpath trajectory back to
town, and perform quality control checks on the data to ensure the
survey contractor obtains and records data correctly. In town, the
Operations Engineer in the Drilling Office receives the Survey data,
adds it to their COMPASS database, and shares it with other parts of
their organization or partners.

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Both engineers may perform Anti-Collision scans down the active well
to assess the collision risk. Also, they may compare the actual wellpath
trajectory with the directional well plan to ensure the well is on track. If
the well veers away from the Plan, they can do Back-On track
calculations to steer the wellpath back to its planned trajectory.

When the well is completed, the final Definitive Survey is composed,

locked, and made available for use with Anti-Collision scanning or
Sidetrack planning on future wells.

A Directional Contractor may use COMPASS to plan a well on behalf

of an Oil Company. At the rigsite, contract Surveyors and Directional
Drillers use COMPASS to enter Survey data as it is received at surface
or read on the drill floor and a comparison made with the planned
trajectory. The data is checked for errors and then reported to the Oil
Company representative in the form of reports, graphs, or wallplots.

The contractor can also provide the data electronically on floppy disk or
send it across a network. If their client also uses COMPASS, they can
send a transfer file to the Company Representative or Drilling Office.

Directional Well Planners specialize in designing and assessing

wellpaths for a number of conditions.

In addition to planning wells through various targets and assessing the

plan for a collision risk, they use Geologic targets provided by the
Geoscience group to construct Drilling Targets. This is achieved using
survey tool error models applied down the planned wellpath to reduce
the size of the target surface. This enables the planner to design a cost
effective survey program applied to the given geological target sizes.

A Survey Focal Point is responsible for maintaining an accessible

quality-checked survey database for an oil company. They can also be
involved in analysing positional uncertainty error models associated
with different types of survey tools. Based on the accuracy and
reliability of different tools, they can recommend the use of certain tools
to the Well Planning group.

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Single User and Network Installations

COMPASS and Wellplan can be installed standalone for a single user or
site or installed centrally on a network for multiple users.

A typical installation at the rigsite is standalone with all components

located on a single hard disk drive. Additionally a backup PC may have
COMPASS installed on it to be used with a backup copy of the database
should the main PC become unavailable.

In the office, a network installation enables most components to be

shared centrally on a network drive including a multi-user database. A
minimum local directory structure is used for storing user unit sets,
catalogues, custom report and wallplot formats, and optionally
COMPASS databases.

COMPASS and Wellplan is licensed software provided by Landmark.

The licensing mechanism is independent of the software and may or
may not be configured the same way as the software itself, as different
installations have different forms of licensing. Standalone licensing is
provided in the form of a bitlock. This is a special hardware device that
is plugged into the parallel port (LPT1) of the PC. Users on a network
may use Network Licensing.

This form of licensing uses a lock file configuration that keeps track of
the number of users using different parts of the software. Network
licensing uses a first come-first served principle and users can access
COMPASS modules provided licenses are available.

COMPASS is broken out into 4separate licensed components:

• Main screen plus Survey Module

• Planning module
• Anti-Collision module
• (SESTEM - for Shell use only)
If a license to any Wellplan or COMPASS component is not available
when launched, a warning message similar to the following window
appears and you must obtain a license to COMPASS before it can be
used.

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Introducing Directional Drilling

This section briefly introduces directional drilling and survey

measurement techniques, and describes the hardware technology related
to use of COMPASS. This section is not intended as a complete
reference and there are numerous, more thorough publications that deal
with this subject.

Directional drilling is the science of drilling a well so its trajectory

follows the planned path to one or more drilling and/or geological
targets. The well must be drilled precisely using the planned directional
parameters designed for the well. If the well steers off course, the
trajectory must be redesigned and drilled to get the well back on track.

Different planning techniques enable wells of varying complexities to

be planned. Different tools enable the well to be drilled and surveyed so
the trajectory drilled is physically as close as possible to that of the plan.

Origins
Directional drilling has always been a part of drilling. In the early days
of drilling at Spindletop, Texas, resourceful drillers put wooden wedges
(Whipstocks) down wells to deviate them towards nearby gushers. This
practise was known as poaching. To prevent this, laws were enacted that
required wells to be positioned within a lease boundary and wells had to
be inspected for deviation by the Texas Railroad Commission & other
bodies.

The same methods of deviation and measurement enabled wells to be

deviated under obstacles, such as cities, lakes, seas, mountains, shallow
gas, and pipelines. Sidetracks are wellpaths intentionally deviated from
the original hole for getting past fish (lost drill string), correcting
unwanted deviation, or reusing an old hole to reduce costs.

Blowout relief wells started in the 1920’s and required precision control
to drill the relief well within a few feet of a blowout well. Early survey
instruments were developed to meet the requirement to know the exact
trajectory of both blowout and relief wells. When the relief well was
determined to be close to the blowout well, cement was pumped to plug
the formation and control the pressure. In modern relief wells, magnetic
ranging methods are used to accurately position the well near to the
blowout.

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Platform Drilling negates the requirement for additional platforms. A

single template underneath the platform is used to access a number of
locations within a reservoir. Deviated wellpaths permit tapping an
extended area of the reservoir from a compact drill site.

Salt Dome drilling is performed to access traps that form on the

upthrown side of the plug. Drilling can be problematic due to plastic salt
deforming casing and high pressure gas at shallow depths. Sidetracks
are made to re-use wells from depleted zones and to drill new ones.

Planned and unplanned deflections are called doglegs. Bit Walk is a

natural tendency for BHAs to steer off course due to formation and BHA
effects. Planned well trajectories can be corrected for this effect to lead
the well on target.

The following graphic depicts the origins of Directional Drilling:

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Early Means of Directional Control

Oriented Drilling
Directional drilling began with the use of devices such as whipstocks or
techniques such as jetting, rotary assemblies to maintain course, and
wireline steering tools to orient and survey.

Whipstock is the name of a wooden wedge that was the first widely-used
deflection tool for changing the wellbore trajectory. It was run and
oriented on drill pipe and the drill bit was deflected off it, provided the
whipstock was harder than the formation. Use of a whipstock was
problematic because a fill in the hole could seriously impede its
performance. Also, much experience was required to use this method
effectively.

The fulcrum and pendulum bottom hole assemblies are mechanical

methods of increasing or decreasing hole angle once an angle is built.
All BHAs cause a side force at the bit that makes the bit build, drop, or
hold angle and turn to the right or left. BHAs can be designed to provide
a desired performance. This technique relies on precise stabiliser
placement and blade diameters that are used to stand-off and pivot the
collars and bit. This functionality, used with the natural turning
characteristic of different bit types, provides drillers with three-
dimensional, rotary, directional control.

Keeping the well vertical is very difficult in areas of dipping or hard

formations. The weight applied to crush rock at the bit buckles the pipe
and causes deflection into the dip. Heavy collars and pendulums are
used to counteract these trends.

An example is ‘Oklahoma measured depths’ which was an early study

to determine the pipe depth required to reach top reservoir. Some wells
required 10-50% more pipe to reach the reservoir in so-called vertical
wells. This was because hard okie formations required much weight to
be drilled. The large compressive forces caused buckling in the drillpipe
which caused the drillstring to be deflected.

Jetting is used in soft formations (gumbo) where one nozzle in a tri-cone

bit is enlarged and oriented to create a rathole, into which the string is
dropped. The technique has been very successful in the Gulf of Mexico
but has not had much success in the North Sea. Jetting uses the hydraulic
energy of the drilling fluid to erode a hole along a given azimuth. The
string is dropped into the rathole.

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This jet and drop procedure is performed for 3 to 6 ft. without rotating
to establish the new direction. Rotary drilling then proceeds until a
survey is taken to verify the new wellbore trajectory.

This technique is dependent on the formation being drilled. Weakly

cemented sandstones and oolitic limestones prove good candidates
while very soft or hard formations fail due to the jet blowing away too
much hole in soft formations and not having sufficient power to make
new hole in hard formations. The primary advantage of jetting is that it
can be performed with the same BHA used to drill.

Survey Measurement
The wellpath trajectory is determined by measuring the inclination and
direction at various depths. Early measurement tools included the acid
bottle and punch card which were used to record inclination to indicate
whether the trajectory had deviated. These tools were run on slick-line
(steel wireline). Hydrofluoric acid was poured into a glass bottle and
etched the bottle at the angle at which it came to rest. The punch card
technique was the basis for the TOTCO tool used for inclination
measurement.

Magnetic and gyroscopic tools are used to record inclination and

direction. They use either a single or multi-shot timed camera or
sensitized paper to record stations for deviated wells. Gyros are usually
run on a conductor cable which supplies power and can be used to
transmit readings to the surface. Other gyros are battery-powered and
are run on a wireline inside casing. Magnetic multi-shot tools are run on
a slick-line, sand line (braided cable), or dropped inside non-magnetic
collars and brought back to surface as the string is tripped.

The muleshoe ensures that the single shot survey tool is consistently
located inside the bottom of the BHA relative to the bent sub, jetting bit,
whipstock wedge, underguage stabiliser blade, or other tool used to
orient the BHA. As the survey tool lands in the BHA, a stub in the
muleshoe landing ring (in pipe) draws the recess in the survey tool spear
point round so that the tool seats in the direction of the tool face. For
quality control, a lead slug is seated in the recess to indicate a good
survey orientation. Marks in the slug indicate that the landing ring had
seated right into the muleshoe recess.

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The following graphic depicts the early means of directional control:

Modern Directional Drilling

During the 1970’s, directional drilling requirements escalated on
platforms designed to access large parts of the reservoir. Drilling at
these sites became more complex as the fields matured and wells were
safely directed around existing producing and injecting wells. During
the 1980’s and 90’s, directional drilling techniques and equipment
improved dramatically due to requirements to drill a large number of
horizontal wells though fractured limestone reservoirs to increase
production instead of vertical wells. The Austin Chalk in Texas and the
Cretaceous chalks in the North Sea were driving areas of this
cost-effective technique.

Extended Reach Drilling (ERD) wells are defined with departures which
exceed twice the well TVD. Different classes of ERD well have evolved
based on increasing Reach/TVD ratios. These include conventional
directional drilling (<2.0), ERD wells (>2.0), and severe ERD wells
(>3.0).

Modern equipment and techniques can drill wells with 10km stepouts at
only 1.5km depth. The best example is Wytch Farm in southern England
where the Sherwood Sandstone reservoir underlies Poole Bay which is
environmentally protected. Parts of the target are problematic in that the

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reservoir dips onshore requiring the wells to hit the target downdip,
build, and drill up through the reservoir. These extended wells have been
used as a test site for some of the emerging technologies described in
this section. Even greater ERD wells are being drilled all the time.

Horizontal Wells were pioneered in fractured chalk reservoirs where

vertical wells are uneconomic, because they fail to hit vertical fractures.
Examples include Farmington (short radius), Austin Chalk (medium
radius) and offshore Denmark (long radius). Horizontal wells are now
used in reservoirs where greater life and productivity can be expected
from fewer wells by limiting Water and Gas coning. The economic
success of these wells has resulted in horizontal wells becoming the
norm. The question now is ‘why drill a vertical well?’

Heavy Oil projects (Alberta, Canada) require steam injection from

horizontal wells to warm up the viscous and make it mobile so that it
flows into an adjacent parallel wellbore- this is an example of an
Enhanced Oil Recovery (EOR) method. One well is drilled for
production and a second steam injection well is drilled 10/20’
underneath using magnetic ranging from the MWD to the magnetized
casing of the top wellpath. The hot steam from the injection well reduces
oil viscosity, enhancing oil flow into the overlying producer.

Multi-lateral wellpaths are drilled from the same well. Laterals are
planned side-tracks where each path is selectively available to
completion equipment.

River crossing is where a hole is drilled under a river to carry a pipeline

or cable. The hole is drilled and widened using a mining rig on a truck
and deviated up to a target location. Then the pipeline is attached to the
bit and pulled back through.

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The following graphic depicts modern directional drilling techniques:

Mud Motor
The mud motor is the workhorse of modern directional drilling
representing a major advancement in directional control. First employed
in the oil field by Dynadrill (Smith, Halliburton, now Pathfinder) in
1968 as a directional tool, Positive Displacement Motors (PDM) offer
greater torque and better pressure feedback than turbines. Drilling with
motors is easier because the surface standpipe pressure reflects motor
torque, which in turn can reflect weight on bit (WOB). As motor torque
increases, standpipe pressure increases and vice-versa. Therefore, the
directional driller uses standpipe pressure to advance the bit by
controlling torque. If the bit stalls you get an increase in pressure.

The motor is composed of 4 standard sections:

• The Dump Sub is used to divert mud so that the roughnecks don’t
get wet feet. It is used to bypass the fluid from the motor while the
tool is tripped into and out of the hole. Essentially it enables the
drillstring to fill with mud from the annulus while tripping in, and
enables the drillstring to drain while tripping out – this prevents it
from flowing out onto the drillfloor when a connection is made.

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When the pumps are started, the fluid forces a piston down, closing
the bypass ports, directing fluid through the motor.
• The Power Section converts hydraulic horsepower into mechanical
horsepower, resulting in drill bit rotation. It consists of two parts,
the rotor and the stator, that when assembled form a continuous seal
along their contact points. The rotor is an alloy steel bar shaped into
a helix and is specially coated in chrome to reduce friction, wear
and corrosion. The stator is a length of tubular steel lined with an
elastomer compound shaped into a helix to mate with the rotor.
PDMs use a reverse application of the Moineau pump principle to
generate power from the mud stream. Slugs of mud are driven
through slots in the rotor/stator, generating torque, which causes the
rotor to cycle backwards through the grooves in the stator
(epicyclical motion). Different rotor/stator lobe ratios (1/2 5/6 9/10)
are used for more power and lower speed. The most common PDM
is a half-lob motor where the rotor has 1 lobe and the stator 2. PDMs
always have 1 more lobe in the stator than the rotor, this results in a
progressive series of cavities for the fluid to flow. The pressure of
this fluid causes the rotor to rotate. Torque is then transmitted to the
Universal Joint.

• A Universal Joint forms the coupling assembly which converts the

epicyclical motion of the rotor into rotation at the drive shaft which
is connected to the bit. It is either a U Joint (Car FWD) or a solid
piece of Beryllium Copper.
The Bent Housing was originated in 1982. Previously a bent sub was
used above the motor. The bent housing allows the whole motor to
be rotated to drill straight, or oriented from surface to drill at an
angle. Bent housing angles are now adjustable.

• The Bearing Assembly supports the motor drive shaft that transmits
drilling thrust which turns the bit. It consists of on and off bottom
thrust bearings and radial bearings. Of all the components in a mud
motor, the Bearing Assembly is most exposed to harsh conditions.
Controlled curved wellpaths are drilled using a sequence of curved/
oriented and straight/rotating sections. The bend is always over
designed by 25-50%. The Stabiliser on the bearing housing is used
to balance the bit and the bend for optimum direction control. MWD
data will tell the Directional Driller which way the bend is pointing
and the inclination and azimuth of the well heading.

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The following graphic depicts the Mud Motor:

Measurement Systems
Accurate knowledge of wellbore position is important to:

• Optimize the recovery from a reservoir by strategic positioning.

• Build an accurate 3-dimensional map of reservoir surfaces.
• Enable the well to be relocated in the event of an underground
blowout.
• Prevent loss of wells and damage caused by inter-well collisions.
Modern wellbore surveying tools to achieve these objectives include
MWD and Gyros.

Magnetometers are the primary measurement method used while

drilling. The MWD and Multi-shot tools have triaxial magnetometers
and accelerometers. Magnetic surveys are affected by variations in the
earth's magnetic field and also from steel from the drill string, they
require special non-magnetic drill collars to be spaced about the survey
tool.

Gyroscope surveying is used to obtain more accurate logs and are

normally run inside casing, although some gyros have been adapted for
pump down and MWD.

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The rate gyroscope has become the standard in the business, it was
developed for cruise missiles. It uses one fixed axis gyro, its gimbal axes
are held steady by electro-magnetic resolvers. The current required to
prevent swing indicates the rate of turn of the assembly. They are
sufficiently sensitive to pick up the earth’s motion. This is gyro
Compassing and is used to detect the initial angle of the tool, the sensors
then detect movement as the tool moves down the wellbore on wireline.
The movements are integrated into angles and then into positions.

Because gyros are generally more accurate than magnetic surveys, they
are typically used to correct the wellbore trajectory as calculated from
the magnetic survey data. Magnetic surveys when compared against the
plan can indicate that the well was not drilled to the plan, resulting in
some serious discussion between drillers and geologists. The solution is
to run a gyro and recalculate the wellbore trajectory to see how it
compares against the plan.

The following graphic depicts Magnetic and Gyroscopic Systems:

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Measurement While Drilling

MWD tools are instruments that signal the surface with information
about the wellbore and formation at the drill bit. The first application
was directional information (Inc/Azi) which replaced the existing
single-shot instruments.

In the early 1980’s, formation information was available that included

short normal resistivity and natural gamma ray tools. Recent
developments include sensors that measure formation acoustic velocity
(sonic) and provide electrical images of dipping formations. These types
of tools are called Logging While Drilling (LWD) as the quality data
they provide results in equivalent wireline runs no longer being
required.

MWD tools typically consist of a power system, telemetry system,

directional sensor, and formation measurement tools.

• Power is supplied to the tool by turbine or batteries. Batteries can

supply tool power without drilling fluid circulation. Turbine energy
is abundant as it is supplied by fluid flow.
• The Telemetry equipment transmits data back to surface. The
signals are sent via mud pulses, which are interpreted by a pressure
transducer in the stand pipe at the surface.

An example is negative pulse, made by diverting mud from the pipe

to the annulus it reduces the pressure in the stand pipe. Pressure
pulses are slow. A single pulse takes about 1 second to transmit. A
digitized angle (Toolface) can take 10-20s to transmit in digital
form.

Positive pulse is also widely used, where the pulse is cause by a

valve restricting flow in the pipe. Both use a solenoid driven by a
bank of capacitors to drive the valve. Other methods for signalling
the surface has been tried like cable in the pipe (wears out quickly)
and radio transmission (VLF is used but limited by depth).
• Directional survey information is detected by triaxial
magnetometers (electronic compass) and triaxial accelerometers
(electronic plumb bob).
• Geophysical traces are transmitted for Geo-steering, These are the
Gamma Ray detector (a Geiger counter) and Resistivity (via
electromagnetic wave coils).

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• At surface the pulses are converted into log data which is made
available at the rig floor in terms of dial readings and to the
operator in the form of logs. Log plotting requires a depth tracking
system and computer software.
• Recent additional information provided by MWD systems include
downhole WOB, downhole pressure at bit (PWD), drillstring
dynamics data (vibration), neutron porosity, bulk density, and
ultrasonic calliper measurements. This type of information is used
to aid geo-steering.
The following graphic depicts the MWD at Rigsite:

Inability to steer mechanically while rotary drilling resulted in the

design and implementation of Variable Blade Stabilisers (VBS) also
known as Adjustable Gauge stabilisers (AGS). These tools are designed
to enable blade diameters to be changed while drilling.

These tools, along with other fixed-gauge BHA stabilisers, are used to
change the build and drop tendency of rotary and steerable BHAs with
a simple pumps-on/pumps-off procedure. This enables BHA steering
tendency to be changed to downhole without having to trip the
assembly.

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Other benefits include the ability to control inclination when sliding is

no longer possible, improved hole cleaning due to continuous rotation
of the drill string and torque/drag tortuosity reduction by limiting dogleg
severity.

Emerging Technologies
A number of new technologies are being employed in directional
drilling to enable extended reach or designer well trajectories to be
achieved.

Coiled Tubing/Under Balanced Drilling

Coiled Tubing (CT) rigs were originally developed for workover
operations inside existing wells, but now have been adapted for
sidetracking and drilling. CT rigs can drill short length wells (1500’
horizontal) at lower cost and time than a conventional drilling rig (with
a smaller footprint). The coiled tubing (2” steel) is coiled onto a drum
and fed into the wellbore through an injector with spools that can push
or pull the tubing into the hole. The standard steering combination of
bent mud-motor and MWD has been modified for CT with the addition
of a ratchet indexing device for orienting the motor bend. This is used
because CT cannot be rotated for orientation.

Underbalanced Drilling (UB) is a method where the drilling fluid is

made less dense than the formation fluid inside the reservoir. The
consequence is that the formation fluid flows into the wellbore. This is
desirable because if the drilling mud overbalances pore pressure, it will
invade the reservoir pore space and reduce permeability. This results in
reduced formation productivity, particularly in horizontal wells where
the reservoir is subject to longer contact times with the drilling fluid and
open hole completions are more prevalent.

In addition to reducing formation invasion, under balanced drilling

results in reduction of drilling time due to increased ROP, increased bit
life, and less chance of differential sticking. In normal drilling, lower
mud densities are avoided because pressure problems (blowouts) will
occur which can be difficult to control.

In UB drilling the pressure can be regulated with a special blow-out

preventer and choke at surface. Fluid densities can be reduced by foam
drilling or injecting nitrogen into the drilling fluid. Special equipment is
used at the surface for solids separation and cuttings sampling.

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A major drawback with the technique has been the inability to use
MWD, and therefore geo-steer, due to the presence of compressible gas
in the annulus preventing mud pulse systems transmitting back to
surface. Electro-magnetic tools (EMT) have solved this problem for
shallow wells enabling direct transmission back to surface. Depth and
temperature restrictions in addition to formation restrictions have
limited the use of EMT though repeaters/transmitter technology seems
to enable EMT tools to be used at deeper depths.

The following graphic depicts the Coiled Tubing Rig and

Under-Balanced Drilling:

Multi-Laterals
Planned multi-lateral (ML) wellbores are now a part of modern
completion practices. Lateral wellbores allow simultaneous production
from two or more zones without the cost of the extra upper wellbore and
surface equipment. Second and further wellbores can be drilled at 30%
of the cost of the original well. This method only suits reservoirs that
have good mechanical stability.

ML wells comprise a parent wellbore with one or more secondary

wellbores (laterals) all of which produce or inject fluids or provide

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 Chapter 2: Directional Drillling

information. They are classified based on the junction mechanism

between the parent and sibling wellbores.

Whether the junction is open or closed, or whether the tubing or casing

is installed across the junction determines a ML well’s classification. A
common classification scheme contains 6 variants with increasing
complexity:

This classification... Has these features...

Level 1 No zonal isolation, such as openhole sidetracks.

Specific branch access is difficult, sometimes
impossible.

Level 2 Cased and cemented parent wellbore with a milled and

slotted liner in the sibling but provides no zonal
isolation or pressure integrity across the junction.

Level 3 Contained cased and cemented parent and sibling

wellbores with cement or epoxy at the junction. The
junction provides no zonal isolation and cannot sustain
a differential pressure greater than the formation
fracture pressure.

Level 4 Same as Level 3 but contains cement at the junction

designed to provide pressure support greater than the
fracture pressure. Packers in the parent wellbore
provide zonal isolation by being placed on both sides
of the sibling.

Level 5 Achieves full zonal isolation using a downhole

deflector at the junction and a system of packers in
both parent and sibling wellbores. This enables
production tubing to be mechanically sealed.

Level 6 Uses mechanical splitters to achieve full zonal

isolation along both branches.

The lateral wellbore shown below (Level 3) is constructed by installing

casing in the primary wellbore with a window joint positioned and
rotated in the desired direction. A protective sleeve is removed and a
drilling whipstock is oriented and installed. The window is opened with
a milled tooth bit run on a steerable motor.

Once the lateral is drilled the junction is cased off with a short liner, the
section of the primary wellbore is washed over and recovered. Drilling
of the lower lateral is then performed through the primary wellbore.

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Chapter 2: Directional Drilling

Re-entry into the upper lateral can be performed at any time by

installation of a retrievable workover whipstock.

The following graphic depicts the Multi-Lateral Level 3 Completion:

ML wells can also be classed on their relative geometry. Different types

include:

• opposed dual laterals

• stacked dual laterals
• multi-laterals
• branched multi-laterals
• splayed multi-laterals
• forked dual laterals

Rotary Steerable Systems

Rotary steerable devices (also known as Steerable Rotary Drilling -
SRD) enable inclination and azimuth correction during rotary drilling.
The concept was first introduced in 1991 by Camco. Currently (1999)
there are 5 rotary steerable systems in an expanding market. A number
of different types of systems are being tried.

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 Chapter 2: Directional Drillling

Rotary steerable systems offer considerable advantages over the

steerable mud motor system:

• Drillstring torque and drag should decrease resulting in less

tortuous wellbores. This should reduce stuck pipe, make workovers
and completions easier.
• Drilling in rotary mode should reduce bit walk.
• ROP should increase 50-100% by enabling bits to be selected on
performance reasons rather than steerability.
• The number of trips required to directionally drill a well should
decrease.
• LWD data quality should improve due to drilling in rotary mode as
well as because the data is obtained closer to the bit. Drilling course
corrections will be made earlier.
• Cuttings transport is better in rotary mode resulting in easier hole
cleaning, less chance of forming cuttings beds and getting stuck.
• Fewer wiper runs are required (smoother wellbore, less cuttings
beds, and so on).
• Dogleg severity and wellbore spiralling should decrease resulting
in easier completions.
• Steering should enhance production by keeping the well within the
reservoir.
In comparison, mud motor systems are slow when steering because the
drill string is not rotating and the string will pick up friction and cuttings.
The resultant extra drag becomes so great that the motor becomes
unsteerable especially if the pipe buckles. A rotary steerable system will
drill faster and further. They do not offer the range of radii of motors,
therefore they are best suited to extended reach wells.

A rotary steerable device consists of 2 sections:

• The bias unit is located immediately above the bit. It has three
actuator pads which can be operated in synchronism with rotation
of the bit in order to provide a lateral displacement in a constant
direction and hence steer the well. The pads are operated
hydraulically using the drilling fluid and are controlled by a rotary
valve which is mechanically connected to the control unit.
• The control unit is mounted inside a non-magnetic drill collar and
contains a directional sensor package, roll sensors, and control
electronics.

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Chapter 2: Directional Drilling

The example below (a hybrid of 3 designs) has a non-rotating stabiliser

body with 3 buttons on hydraulic pistons in each blade. Pressurised oil
is driven through a rotating valve to one blade’s pistons. This imparts
thrust to the wall which by reaction will drive the bit in the opposing
direction causing it to drill laterally by side cutting.

The rotating valve determines which direction the thrust moves, the
valve itself is driven by electric stepper motor at to a position which is
synchronised with the rotation detected by a Hall effect transistor.

An oil pump is driven by the rotation movement.

The following graphic depicts the Hybrid Rotary Steerable Device:

Geo-Steering
Geo-steering is directional steering within the close confines of a
payzone. Wellpath adjustments are made based on real time geological
and reservoir data in addition to drilling observations. The goal is to
maintain a bit position at an optimum depth near the top of a producing
formation.

Geo-steering enables the planned wellpath trajectory to be evaluated

against the geological model as the well is drilled. The planned build
trajectory may be compromised by inaccurate depths from seismic data,
resulting in the formation tops coming in high or lower than expected.

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Formation markers are detected by Gamma/Resistivity sensors while

drilling the well. The planned trajectory is adjusted to any changed
formation tops to ensure the well meets it geological requirements.

Steering in the payzone is achieved by watching the petrophysical

sensors for signs of the producing formation and steering away from
poor formations. Shales and non-productive formations have high
gamma counts (radioactivity) and low resistivity. Productive formations
are ideally clean of radioactive clay minerals and therefore show low
gamma counts and high resistivity (especially in oil/gas zones).

Geo-steering equipment consists of detectors near the bit which provide

faster reaction times than sensors located 40’ to 80’ behind the bit. This
enables thinner zones to be drilled with confidence. In a thick productive
zone other indicators may be used such as examining cuttings from the
shale shakers, looking for microfossils in limestone, or evaluating
hydrocarbon returns at surface. These measurements can be more
immediate if ROP is low through the reservoir.

The following graphic depicts Geo-Steering Equipment at the Bit:

To maintain quick reaction times, geo-steering is a team effort requiring

close co-ordination between the driller, the directional driller, MWD
operator, and the geologist interpreting the formations.

With a typical ROP of 30ft/hr, the engineers have two data points per
foot on which to interpret the well against the predicted geological/
petrophysical model. Log curves must be compared and interpreted
against predicted responses to ensure that the well is drilled to its
planned target. These interpretations are fed back to the directional
driller and adjustments made to the well trajectory where necessary.

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Chapter 2: Directional Drilling

The following graphic depicts the geo-steering as a team effort at the

rigsite:

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 Chapter 3: Getting Started

Getting Started

COMPASS is part of the Drilling2000 product suite packaged together

with Landmark’s other engineering applications Wellplan, StressCheck,
WellCat and Casing Seat. These and the other Data Management
applications may be integrated automatically using the Drillability Suite
Manager application or manually using Data Exchange (DEX).

Compass historically was packaged together with WELLPLAN for

Windows. They are now separate products with different install
directories. COMPASS may or may not be installed with WELLPLAN
depending on whether the company purchased both products.

For COMPASS installs, you have three tools within the Landmark
Drilling & Well Services/Planning/COMPASS 1998.7 Program Group
and Documentation & Tools sub-groups:

• The COMPASS icon that is used to launch COMPASS. This

may be used to create a Windows shortcut that you place on the
desktop to launch COMPASS
• Landmark Home Page that accesses the Landmark Graphics Home
and Support pages if you have Internet access
• Installation Guide
• Release Notes that provide important information about the current
release, including new features, bug fixes, known problems, and
how to get support when problems occur
• 1998.7 Database Upgrade Wizard to port a v1998.2 COMPASS
database to 1998.7
• Bitlock Status to output the licensing details configured on a
Sentinel dongle currently attached the PC parallel port
• Select Data Sources for COMPASS, its local unit management
system (UMS), and its network unit management system
• Unit System Upgrade Wizard to port Units sets from 16-bit
Wellplan to 32-bit COMPASS

Starting COMPASS
You can start COMPASS in two ways.

• Click the Program Group icon to launch COMPASS.

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Chapter 3: Getting Started

• Double-click any desktop shortcuts you have configured.

After COMPASS launches, a splash window appears displaying
licensing and install information if you are licensed to use COMPASS
for Windows. Next, the main COMPASS window appears. If you are
connecting to a multi-user database such as Oracle, you will be
prompted for a user name and password.

Application Layout Overview

COMPASS is designed around a Microsoft Windows MDI (Multiple
Document Interface) area. Data entry and analysis are performed in
separate windows that you view simultaneously within a central
application area. COMPASS itself is composed of the distinct tool areas
shown below:
Landmark Internet Support Site Connection,
doubles as ‘Busy’ Indicator
Menu Bar
Tool Bar

Status Window

Browser

Datums Reference

MDI Document
Area. Will display
any number of
screens
simultaneously

Status Bar

Unit Set Name Depth, Angle & Map Units

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 Chapter 3: Getting Started

COMPASS Menu Bar

The menu bar provides access to all tools available within the software.
It is organised into logical areas as follows:

Select... To...

File Open data, Create New Items, Import/Export

functions, Data Exchange between different Landmark
applications

Edit Modify currently open data set.

View Launch certain graphs and Legend, Launch Wallplot

Composer.

Planning Access the Directional Well Planning module.

Survey Access the Survey module.

Anti-collision Access the Anti-collision module.

Utilities Launch utility functions, configure default graph and

report settings.

Windows Change full size windows, Standard Windows menu

item.

Help Access the online Help, current version info.

You can select any item within the menus using the mouse or the
indicated keyboard quick keys.

To use the quick keys to select an item, press ALT and the underlined
character. For example, to import a transfer file from another Compass
site, one would use the File Import Transfer File menu item, press ALT
F M T.

The Survey, Planning and Anti-collision menus are license-driven

through either a dongle, network licensing, or FlexLm file based
licensing. If COMPASS is unable to locate a license for these products,
the menus are still active, but a message box appears informing you of
the license restriction. This event may also occur for network licensed
sites when all available licenses are checked out by other users. You also
find that menus are inactive (greyed out) if a wellpath is not currently
open.

The Survey and Planning modules are mutually exclusive. So if a

Survey is open you can’t access the Planning menu and vice-versa.

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Toolbar Icons
The toolbar is located below the menu bar and enables quick access to
commonly used functions within COMPASS. Intuitive icons indicate
which functionality is accessed by each icon. Descriptive Tool Tips
appear if you pause your mouse cursor over any icon.
Link to Landmark
• Download from COMPASS FTP Site
• Doubles as ‘busy’ indicator
Link to OpenWorks
• Update Wellpath Trajectory in OPENWORKS
Geomagnetic Calculator
• Calculate Magnetic Field
• Vary Surface Location, Date
• Different Global Geomagnetic Models
• Output Results to Text File
Geodetic Calculator
• Convert between Grid & Geographic Coordinates
• Determine UTM Zone
• Calculate Grid Convergence & Scale Factor Reports
• Output Results to Text File • Print Survey Reports

Wallplot Composer
• Custom Design Hard Copy Plots
Definitive Path Spreadsheet
• Listing of Definitive Path
• Interpolate by MD, TVD, Inc or Azi
3D View
• A Configurable 3D Plot
Plan View
• A Configurable Plan View Plot
Vertical Section View
• A Configurable VSec Plot
Graph Setup
• Specify Default Settings for Plots
• Graph Colours and Fonts
Survey Program Editor
• Composition of Definitive Path
• Planned Survey Design Wellpath Target Editor
• View Historical Defn Paths • Edit Target Location and Geometry
• Create Drillers Targets

Annotation Editor
• Edit Wellpath Notes for Plots and Reports

Formation Editor
• Edit Formation Names, Lithologies and Depths

Casing Editor
• Casing Shoe Depths
• Casing Shoe Names
• Casing Diameters
Wellpath Setup
Well Setup • Wellpath Name
• Well Location, either Slot location, local • Sidetrack Tie-on Point
NS/EW, or Map N/Map S • Vertical Section(s) Origin & Angle
• Local Positional Uncertainty • Wellpath Type
• Well Reference Point Definition • Vertical Reference Datum
• Magnetic Field Details
Datum Editor
Template Editor • Edit Vertical Depth Datum References
• Slot Geometries/Coordinates
• Generate Slot Coordinates

Site Setup
Field Setup • Site Name
Survey Tools • Field Name • Site Location Coordinates
• Edit the tool error model and • Local Coordinate System • Water Depth
Company Setup
• Company Name coefficients. Choose from: • Geodetic System • Positional Uncertainty
• Company Logo • Cone of Error • Common Vertical Datum • Grid Convergence
• Anti-collision Models • Systematic Ellipse • Geomagnetic Model • Default Vertical Datum
• Anti-Collision Warning Rules • Inclination Cone of Error • Local North Reference (True/Grid)
• Passwords • ISCWSA
• Survey Calculation Method • Tool Import/Export
• Re-Validation of Data
• Vertical Section Convention

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Common buttons are used throughout COMPASS. These icons have

consistent behaviour and makes the software more intuitive to use:

Click... To...

Apply those changes to the rest of COMPASS and/or the

COMPASS database, then Close the window. Use this
when you enter new data or change existing data. For
windows that require calculations, this button is usually
greyed out or inactive until a calculation is made.

Close the current window without saving.

Display help for the current window.

Perform a calculation now that the required parameters

are entered. Note that after a calculation, the OK button
usually becomes active to save the calculated values.

Export all calculated results displayed in the current

window. Put the results and any associated data into an
Text file and view it using the Windows Notepad
application. This is a useful feature for Printing,
Emailing, Copying, or Faxing calculated results.

Certain windows or editors enable addition, modification, or deletion of

list items such as Templates, Targets, and Survey Tools. The following
toolbar icons enable you to perform these actions.

Click... To...

Save and add a new item to a list, for example a new

Target or create a copy of an existing survey.

Save changes to the database for an existing item, for

example a target location has been changed, survey
needs updating.

Delete an item from a list, for example a Target.

Close the editor. Will prompt for Save/Update if data

has changed.

Fire up the help page related to the currently open editor.

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Chapter 3: Getting Started

NOTE:

Some items cannot be deleted, for example Survey Tools used

within any Definitive Path, locked Surveys, or Surveys included
in a Definitive Path.

Status Bar
The status bar is the information area at the bottom of the COMPASS
window that displays Help and Units information. To the right a units
summary field displays the name of the currently open units set. A
second field displays what type of unit set is being used by displaying
the currently configured Depth and Angle units, such as ft & deg. If a
numeric data entry field for any window within COMPASS has focus,
the adjoining status field to the right displays the configured unit for that
data entry field.

Status Window and Browser

The Status Window displays the currently open data set, the Company,
Field, Site, Well, and Wellpath. It also displays some other reference
information. The right side contains a data browser that you use to view
and open data different levels within the COMPASS data model
hierarchy and see what types of data have been entered for a given
structure. Using drag and drop, you can also copy data between different
areas. You’ll find that the Status Window and Browser is always
available, you can minimize but not close this window.

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 Chapter 3: Getting Started

The following graphic depicts the Status Window and Browser:

Data
Browser

Active Data Set

Datum Reference
Information

Co-ordinate Data Viewer

System Reference

Both the Status and Browser areas in the Status Window display
whether data at a particular level has been locked. This is achieved by
displaying ‘padlock’ icons adjacent to the data. Company, Field, Site,
Well and Wellpath setups may be locked as well as individual Plans and
Surveys. This prevents locked data being mistakenly modified or
deleted.

The following graphic depicts Status Window locked data icons or

padlocks:

Status Area Locked Data Padlocks Browser Area Locked Data Padlocks

In a multi-user database different users use COMPASS at the same time

to access the same data source. In this environment, it is useful to know
if another user is currently using a data set. The Browser window

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Chapter 3: Getting Started

signifies data being used with a large red cross over the +/- expand/
contract icon so users know someone else is accessing it.

Using the Online Help

The online Help System is remarkably comprehensive and is geared
towards engineering descriptions and solutions instead of the simple
‘What does this button do?’ type Help usually available in other
Windows applications. Much of the Help has been written after
reviewing frequently asked questions from our clients stored in
Landmark’s Call Tracking System. See the Frequently Asked Questions
section in the Help for details.

You access context-sensitive online Help as follows:

• From the COMPASS main menu select Help then Contents.

• Click the Help button located on most windows (question mark)
• Press F1 on your keyboard
The Help functions the same as other Microsoft Windows applications.

The following graphic depicts the COMPASS Help Contents:

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 Chapter 3: Getting Started

Finding Information in Help

Once in help, you use the Help Toolbar to find desired information as
follows:

In addition there are hotspots embedded in the text that provide more

Click... To...

Help Topics Go to the main Help Contents (shown above).

Search by subject areas, search by indexed
keywords, or search through Help database

Back Go to the previous Help topic.

Print Print the current help page.

Browse Keys (<< and >>) Browse through related topics.

information.

Click here... To...

Jump Hotspot – (solid Jump to another related topic.

underlined green text)

Popup Hotspot – (dotted View descriptive information in a popup

underlined green text) window.

Frequently Asked Questions

The Help file contains a FAQ topic area that can be found in the
Introduction section of the Help file. If you have an urgent question, it
could well be that a number of engineers have already asked the same
question and it is included in the FAQ.

Units
The COMPASS Units Management System (UMS) is accessible from
the Utilities menu and may be standalone or shared with other
COMPASS and WELLPLAN users. The essential function of the units
editor is to configure display units for each unit class and organise them
into unit sets. Display units are distinct from storage units that are fixed.

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At any time, you may change the display units used by COMPASS and
automatically convert any values with no adverse affects to the data or
results. This also means you can share data with other users or clients
who use a different unit set. They automatically see your data in their
units.

For applications in WELLPLAN and COMPASS, only some units are

meaningful for expressing unit types. For this reason, Unit Classes (sets
of units for a particular unit type) are defined.

Examples of Unit Classes are:

• Diameters: [mm], [inch], [cm]

• Depth: [m], [ft]
• Dogleg Severity: [deg/100ft], [deg/30m], [deg/100m], [deg/10m],
[rad/30m], [rad/10m]
The following graphic depicts the COMPASS Units Editor:

Each data entry field in COMPASS belongs to a Unit Class and its value
is displayed in the unit defined for that class. Variables that belong to
different classes do not need to be represented in the same type of units.
For example, while Hole Diameter might be represented in inches
(API), Hole Depth might be represented in metres (SI).

You use the Unit Systems Editor to configure a Display unit for each
Unit Class. These unit specifications can be saved so that each time you
use COMPASS, displayed data appears in the desired units.

COMPASS is shipped with two default unit sets, API & SI, that cannot
be edited. They are provided as a starting point for any customised unit

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 Chapter 3: Getting Started

set that could consist of a combination of API and SI units. Additionally,

there are a default set of units within a given class. You cannot add units
to a particular class.

Oil Companies typically create a unit set for their own employees.
Contractors may create unit sets for each of their clients who receive
WELLPLAN or COMPASS reports or graphs.

Changing units is easy. Launch the unit editor, select a unit set you want
to use, then select a Unit Class. Click on that entry and choose from a
list of units from that class on the right side. Click to choose a unit. You
can make more than one change at a time. When complete, click OK to
apply the changes to COMPASS and/or WELLPLAN. The name of the
active unit set is displayed in the middle of the status bar.

Databases
COMPASS supports any ODBC-compliant relational database, such as
Oracle or Sybase RDBMS. This enables companies to use a database
platform that meets their requirements.

By default, COMPASS is shipped with a runtime license to Sybase SQL

Anywhere, a PC desktop relational database server. When you launch
COMPASS, you also launch SQL Anywhere to manage your
transactions and database files. You can ensure they are running by
checking the Windows Task Bar.
Sybase SQL Anywhere Task Bar icon

COMPASS data sources are managed using a Windows Control Panel

program called 32 bit ODBC Administrator. Use this tool to set up and
configure additional COMPASS data sources. In the title bar of
COMPASS, the data source name is displayed next to the title. It usually
has a name like CFW Single User.

Sybase SQL Anywhere CFW.DB local data source files (CFW.DB) are
typically located in the COMPASS\DB directory that are usually
located on your local hard drive or network home directory. These files
should be backed up regularly. A single user database means that only 1
user can access that database at a time. There is the option of placing
single user databases on a shared network drive so many engineers can
see it. However, unless the company has purchased a multi-user version
of Sybase SQL Anywhere, the one user at a time rule still applies.

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In an office setting, you may have access to a networked database such

as Oracle, Sybase SQL Anywhere, or Microsoft SQL Server on which
COMPASS data can be shared simultaneously. COMPASS transfer
files enable data to be shared between these two types of databases.

Changing Databases
To change databases, the File -> Data Source menu item fires up
window that enables a user to move to a different COMPASS data
source without having to close down COMPASS. The Window contains
a list of 32-bit ODBC data sources. COMPASS data sources must be
constructed before this window can be used. To use, simply select the
other data source and press the OK button.

COMPASS 32-bit ODBC Data Source Selection Window:

1. Click on Data Source

2. Press OK

3. COMPASS closes
current data source and
opens up selected data
source

Network Terminology
In a standalone install, all parts of COMPASS are located in or under the
install directory (e.g. C:\Program Files\Landmark\Compass).
Everything is dedicated to the PC that Compass is installed on.

Client/Server Components
A network install of COMPASS splits system files into two areas:

• Server: a central area shared by all users for the application

executables, libraries, configuration files and customisation files.
• Client: a personal area, one for each user, where the individual’s set
of configuration and data files are stored.

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Network components is a term for shared files, local components is a

term for individual files.

In COMPASS, file sharing can save time. Shared Units Sets enable
consistency of output for all users. Shared Geodetic File formats enable
all users to have the same set of geodetic systems available, this is
particularly useful for customised Geodetic files constructed for a
particular client. Shared Report and Plot Format files enables users to
share commonly used formats or the latest Wallplot formats constructed
by one of the company COMPASS experts. Shared Logo Files enable
the corporate image to be presented consistently amongst all reports and
wallplots.

To share files on a network installation, the following types of files

should be placed in the CONFIG directory:

• Logo or bitmaps files (*.BMP)

• Geodetic config files (*.GDF) and Spheroid files
(SPHEROID.SPH)
• Geomagnetic config files (*.GAM)
• Wallplot Templates Files (*.GTF)
• Report format file (CFWRPT.INI)
• COMPASS Export Files (*.CEF)
Additionally, all these types of files can be stored locally, but only the
person to whom they belong may use or even see them.

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 Chapter 4: Data Structure

Data Structure

COMPASS has a hierarchical data structure to support the different

levels of data that are required by the different parts of the application:

• Company
• Field
• Site
• Well
• Wellpath
• Surveys & Plans
Under each Company you can define several Fields, in each Field you
can define a number of Sites, in a particular Site you can define a
number of Wells, and in a Well you can define one or more Wellpaths.
The Wellpath is the base level of the hierarchy and it is in a Wellpath
that Surveys and Plans are assigned. Other associated data can be
assigned at each level. For example, Company Survey Tool Error
Models, Site Datums, Templates & Targets, and Wellpath Targets.

Generally, when working within a particular COMPASS data set you

are working in one hierarchy and cannot access data outside that
hierarchy. For example, one Company’s data set is not accessible from
another Company’s data set. The exception to this is the anti-collision
scan where it can be made to include offset data from other companies
& fields which share the same geodetic parameters.

Company

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Chapter 4: Data Structure

The Company is the highest data level in COMPASS and is essentially

the organisation to which data in COMPASS belongs to or is developed
on behalf of. You can define several Companies in COMPASS, each
having a different configuration. If you work for an Operator, you would
probably only use one configuration. On the other hand, if you work for
a directional drilling contractor, you may setup several companies for
each of your clients.

Most importantly, COMPASS enables you to customise your system to

company requirements and policy. For example, you can specify:

• Survey calculation method

• Survey tool error values
• Anti-collision preferences

Company Setup
The Company Setup defines standard settings applied to all data and all
users of that data within a company. Once you define a company and it
is approved, company setup should be locked. COMPASS enables data
level security by defining passwords entered through this window.
These passwords should only be known by the Survey Focal Point or
equivalent in a Company. If you forget any passwords you use in
COMPASS, contact Landmark support.

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 Chapter 4: Data Structure

See Online Help for further

information

A Company Logo can be

Survey Error
selected to appear
Models define how
consistently in Reports and
positional uncertainty
Wallplots
is calculated
A Company Password
enables settings to be
applied consistently within
Anticollision an organisation.
Settings define how
wellpath separation Data Passwords enable
is calculated and Field, Sites, Wells and
how collision risk is Wellpaths to be locked to
reported to users prevent changes
Click here to prevent
Warning Levels can
unauthorised modification
be specified which
to Company settings
enable collision risk
to be reported Re-calculate Wellpath Trajectories and Error
consistently Surfaces for all Fields or a selected Field

Names
Company - This name uniquely identifies the specific company
configuration.

Division & Group - Additional company information is for inclusion on

plots and reports.

Logo
This is a drop-down list that displays the bitmap files in the
COMPASS\CONFIG directory. The logo you select can be displayed on
graphs and on text reports. Using the Utilities-Report Setup menu item
to launch Report Setup, you can configure how Company & User logos
appears by default on COMPASS reports. Company & User logos can
also be configured to appear in Wallplots.

NOTE:

Previous versions of the Compass/Wellplan Report Manager did

not support bitmap sizes greater than 64k. This restriction does
not apply to 98.2 or later releases and does not affect logos
configured in the Wallplot Composer.

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Locked
Company Setup lets you configure COMPASS to certain default values.
Click the Locked box to prevent inadvertent changes to these defaults.
If no Company Level Password is set, the window can be locked and
unlocked at will.

Audit Info
This dialog contains information about who changed and when this was
last updated. You may also add notes here for hand over information.

Passwords

Company Level Password

When a password is entered Company Settings can only be unlocked by
re-entering the password. The enables settings, policies, wellpath types
and tool error models to be enforced at various sites within the
Company.

Locked Data Password

In addition to Company settings, Data can be locked to prevent
unauthorised changes. If you create a Locked Data Password, you must
re-enter the password to unlock any locked data. If you do not create a
password, you can lock and unlock data at will. Data can be locked
separately at the Field, Site, Well, and Wellpath levels in the hierarchy.
In addition, individual Plans and Surveys can be locked. Locked data is
indicated on the Status Box and Browser.

Anti-Collision Settings
Anti-Collision preferences are defined at the Company level and used in
the Anti-collision and Survey modules. Normally these settings
correspond to policies written down in the Company’s Collision
Avoidance & Wellbore Surveying manual or equivalent. The following
are brief descriptions for the data structure section. Detailed descriptions
are provided in the Anti-Collision section of this manual.

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Error System
The Error Model defines how wellpath positional uncertainty is
calculated. Wellbore survey instruments are not 100% accurate, this
leads to errors in calculated bore hole trajectory. In COMPASS there are
the following two methods for calculating bore hole positional
uncertainty:

• Systematic Ellipse (also known as Wolff & de Wardt)

• Cone of Error
• ISCWSA
NOTE:

In v1998.7, if you define a Survey Tool Error Model using a

different error model than that defined within Company Setup,
Compass temporarily converts that tool error model to the
Company configured model whenever positional uncertainty is
calculated. Previous versions of Compass did not do this.

Systematic Ellipse
This is based on SPE paper 9223 by C.J.M. Wolff and J.P. de Wardt first
published in the Journal of Petroleum Technology in December 1981.
The model is a statistical treatment of the distribution of errors caused
by internal and external influences. The main theme of the paper
demonstrates that the major causes of error are systematic (i.e. happen
consistently in one vector direction) from one survey reading to the next.

Cone of Error
This model assumes an expansion of an error sphere with depth. This
spheroid can be made to expand at either a constant rate or a rate
dependent on wellbore inclination. The resultant error surface for the
well is a cone.

ISCWSA
The Industry Steering Committee for Wellbore Survey Accuracy has
built a survey instrument error model for solid state magnetic
instruments (e.g. MWD & EMS). The model is based on a paper
published by H.Williamson "Accuracy Prediction for Directional
MWD" as SPE56702. The model vastly extends the work started with
the systematic error model and incorporates the experience of the many
participating parties. In COMPASS the model has been extended by
including a format for defining error terms.

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Confidence Level
State the confidence (sigma) level for the survey errors in number of
standard deviations. The errors defined in the survey instrument error
models have to be defined at a known standard. Error terms are
expressed in standard deviations from the mean (or sigma). One
standard deviation implies that roughly 65% of readings will be within
the stated error, 2 s.d implies that 95.4% of readings will be within the
stated error, 3 s.d implies that 99.5% of readings will be at the stated
error. Confidence levels are required to make risk based decisions on
collision and target intercept calculations.

• Input Errors – is the stated level for the survey instrument errors
in the ‘tool editor’.

• Output Errors – is the level for the ellipse sizes in plots and
dimensions in the error ellipse report.

NOTE:

Default Sigma values are put into these textfields when the Error
Model is changed. For example, if you select Systematic Ellipse,
then the Output errors default to 2 s.d. to represent that Wolff &
de Wardt terms reflected 95% performance.

Scan Method
The purpose of an anti-collision scan is to calculate the distance from the
scanning point of the reference well to the closest point on an offset well.
This distance is also known as the centre to centre separation or wellpath
separation. Different scan methods determine different separation
distances because each technique uses a different algorithm and
therefore, may not find the same closest point as another technique. This
is one of the more important settings that be applied consistently within
a company.

Four Scan Methods are available in COMPASS:

• Closest Approach 3D
• Travelling Cylinder
• Horizontal Plane
• High Side + Azimuth
In the following explanations the reference wellpath is the wellpath that
is drilled or being surveyed. We check the distance from the reference

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wellpath to any number of offset wellpaths. COMPASS scans down the

reference wellpath at intervals defined in Interpolation Interval and
computes the distance to the offset wellpaths using one of the following
scan methods.

3D Closest Approach
At each MD interval on the reference wellpath, COMPASS computes
the distance to the closest point on the offset wellpath. At the scan depth
on our reference wellpath, imagine an expanding bubble or spheroid.
The minimum distance occurs when the surface of the spheroid just
touches the offset wellpath. Because the offset wellpath is now at a
tangent to our spherical bubble, the line of closest approach is
perpendicular to our offset wellpath.

The following graphic depicts the 3D Closest Approach Scan Method

(left), and the Travelling Cylinder method (right):

Travelling Cylinder
This scan method uses a plane perpendicular to the reference wellpath
and intercepting offset wellpaths as they cut through the plane. The
surface resembles a cylinder with the size of the maximum scan radius.
The travelling cylinders method computes distance from the offset
wellpath stations back to the reference wellpath. The benefit of this
method is that intercepts are detected even when the wellpaths are
approaching at a perpendicular. In this case, there may be more than one
point in the TC plane for the same depth on the reference. Depths are
interpolated on the offset wellpaths and resulting in irregular depths on
the reference wellpath. Therefore the 3D anticollision view and
travelling cylinders depth slice option are not possible with this method,
because they rely on regular depths on the reference.

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High Side + Azimuth

The High Side and Azimuth scan method is a variation of travelling
cylinder. This method uses the same perpendicular plane as the
Travelling Cylinder scan method, but toolface orientation from
reference to offset is added to current wellpath direction. Toolface angle
to an offset well is then reported as the angle from the high-side of your
current wellpath + the azimuth of your current wellpath. This method
avoids the confusion in the Travelling Cylinders plot caused by large
changes in toolface angle when kicking-off from vertical.

Horizontal Plane
The horizontal distance from the reference wellpath to the offset
wellpath.

The following graphic depicts the Horizontal Scan Method:

Error Surface
When you select an error model you define how wellpath position
uncertainty is computed. When selecting a scan method you define how
wellpath separation is computed. The error surface allows you to choose
how the radius of the error surface at the reference well scanning point
and the determined closest point on the offset well is calculated.

The two choices are:

• Elliptical Conic
• Circular Conic (Major Axis Conic)

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Add Casing Diameters

The Add Casing Diameters toggle reduces the wellpath separation by
the sum of the casing radii. These need to be defined in the Casing Editor
for the Anti-Collision calculations to recognise them.

If this is selected when performing an anti-collision scan and

determining safety factor, if no casing is present in offset well then
Compass assumes reference well casing diameters using same TVDs. If
this occurs then “No offset casings” will appear in anti-collision report.
The exception is if rule based warning levels are used (see next section).
For risk based rules, both reference and offset wells have to have both
hole size and casings defined or results will not be generated. Further
description of Error Surface algorithms are found in the Anti-Collision
section.

Warning Type
There are a number of methods available for warning the user of
potential collision problems. The choice made here will decide how the
Anticollision Warning Levels are used.

• Error Ratio - The warning given will depend on the ratio of the
separation distance divided by the combined error radii of the
reference and offset wells at a given depth. This may include
casing diameters.

• Depth Ratio - The warning given will depend on the ratio of the
separation distance divided by the depth times a ratio (i.e. 10/
1000 MD) Error values may be added to this cone.

• Rules Based - In this case each offset wellpath is assigned with

a rule. A warning is given if the rule is failed. Risk based rules
define probability how close to drill without a collision.

Anti-collision Warning Type / Rules

This grid is used to define a number of anticollision warning criteria.
The mode of operation will depend on which Warning Type is chosen
in the Anticollision Settings section of the Company Setup dialogue.
You enter warning level values and the recommended action when the
calculated collision risk falls on or below this value. These warnings
appear in the Anti-Collision report and in some of the Anti-Collision
graphs. The text for these warnings is usually defined in the Company’s
Collision Avoidance manual.

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For Error or Depth Ratio Warning Types the rules are evaluated in order
beginning with the lowest ratio (highest risk) first. Enter a ratio value
(lowest first) and the recommended action when a separation factor falls
on or below this value (i.e. ratios 1.0, 1.25 and 1.5 may indicate ’No Go’,
’Shut-in Well’ and ’Planning Limit’). If you have entered Depth Ratio
warnings, the cones of tolerance as the levels (i.e. ratios of 0.0, 0.01,
0.015 represents No Overlap, <10’/1000 and <15’/1000 levels).

The following example depicts three levels of ratio factor warning

levels:

Action to take should

warning level occur

Separation (Ratio) Factor

Rules Based Warning Type

The list will contain all of the possible criteria that may be assigned to a
wellpath. The first entry in the list will be the company default rule. That
means when a wellpath is selected for anti-collision this rule is
automatically selected for evaluation. Other rules have to be assigned
directly in the Offset Wells dialog.

Rule Name – Enter the message that will appear in the report if this
criteria is exceeded.

Rule Type – There are three types of rules, including:

• ERROR RATIO – Will divide separation by the combined

dimensions of error and use this ratio for comparison. A ratio of
1.0 means that when plotted the ellipse boundaries will just
touch.
• DEPTH RATIO – Will form an envelope about the wellbore with
the ratio of depth increasing until Max Radius is reached. A ratio
of 0.01 with a maximum of 10m means that if the distances of
the ellipses plus the of 0.01 times depth (to a maximum of 10m).
• RISK BASED – Will use a probability of intercept to evaluate risk.
A ratio of 0.01 means there is one chance in 100 wells drilled of
intercepting an offset wellbore.

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Ratio / Prob. – Is the error ratio, depth ratio or probability of intercept,

see specifics on rule type.

Max Ratio – Is the maximum radius of the depth ratio.

Conf. Limit –The confidence limit is used with the ellipse dimensions in
the above calculations. It is expressed as the number of standard
deviations from the mean (or sigma). 3 sigma is the commonly accepted
standard.

In this example, the default rule

is a depth ratio. Use for all offset
wells by default

Defaults
Default methods used in COMPASS are defined here. You may be able
to override these default settings at lower levels in the data hierarchy.

Survey Calculation Method

You use survey calculation methods to calculate the final wellbore
position of a second measurement station deeper than a first station
using the position and vector (inclination and azimuth) of the first
station, the vector of the second station, and the measured distance
between the two. Working down the wellpath, a survey calculation
method enables you to determine the total wellpath trajectory.

COMPASS offers four survey calculation methods.

• Minimum Curvature
• Radius of Curvature
• Average Angle
• Balanced Tangential
• Inclination Only

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This setting is the company’s preferred calculation method and can not
be overridden in the Survey module except for Inclination-only surveys.

The following graphic depicts Wellpath Tajectory Calculation

Parameters:

Compass Survey Calculation Plan View (horizontal)

North A2
3 Dimensional View
A1
DNS
RI (radcur)

Great Circle East

DEW
East
Vertical Section View
R (mincur)
RA (radcur)
DL
I1
DMD DVD I2

TVD TVD
Tangents to Sphere V.Section
DVS

General Parameters
• TVD2 = TVD1 + ∆TVD
• NS2 = NS1 + ∆NS
• EW2 = EW1 + ∆EW

Input Parameters
• MD1 = measured depth of top point (ft./m)
• MD2 = measured depth of bottom point (ft./m)
• I1 = inclination of top point (rad)
• I2 = inclination of bottom point (rad)
• A1 = azimuth of top point (rad)
• A2 = azimuth of bottom point (rad)

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Output Values
• ∆NS = change in North/South position between points 1-2 (ft./m)
• ∆EW = change in East/West position between points 1-2 (ft./m)
• ∆TVD = change in true vertical depth between points 1-2 (ft./m)
• DL = Dogleg Angle (rad)
• DLS = Rate of Change of angle with depth in 3D space
• Build = Rate of change of inclination with depth (may be Drop)
• Walk = Rate of change of azimuth with depth (aka Turn)
• ∆MD = MD2 - MD1
• DL = ArcCos (Cos(I2 - I1) - Sin(I1) * Sin(I2) * (1.0 - Cos(A2 - A1)))
• DLS = DL/∆MD
• Build = (I2-I1) / ∆MD
• Walk = (A2-A1) / ∆MD (Note azimuth is normalised for > 180
degree turns)

Calculation Methods

Minimum Curvature (a.k.a. Circular Arc)

This survey calculation method is most widely adopted in the oil
industry. The path taken conforms to the tangential arc in the 3D sphere
shown in the diagram above.

Calculate RF (Minimum curvature ratio factor) Smoothing

Factor
• if (DL < 0.0043633 rad) RF = 1.0
• if (DL >= 0.0043633 rad) RF = (2.0 / DL) * Tan(DL/2.0)
Note: (0.0043633 rad = 0.25 deg)

• ∆NS = ∆MD/2.0 * (Sin(I2)*Cos(A2) + Sin(I1)*Cos(A1)) * RF

• ∆EW = ∆MD/2.0 * (Sin(I2)*Sin(A2) + Sin(I1)*Sin(A1)) * RF
• ∆TVD = ∆MD/2.0 * (Cos(I2) + Cos(I1)) * RF

Radius of Curvature
The Radius of curvature survey calculation produces slightly different
results from the Minimum Curvature method. The path taken conforms
to the two separate radii in the plan and section views shown in the

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diagram above. It does not have a single 3D radius and hence dogleg
severity (DLS) changes over the course length.

• ∆NS = ∆MD * [Cos(I1) - Cos(I2)] / (I2 - I1) * [Sin(A2) -

Sin(A1)] / (A2 - A1)
• ∆EW = ∆MD * [Cos(I1) - Cos(I2)] / (I2 - I1) * [Cos(A1) -
Cos(A2)] / (A2 - A1)
• ∆TVD = ∆MD * [Sin(I2) - Sin(I1)] / (I2 - I1)

Average Angle
Average angle is a survey calculation easily adopted to hand calculation.
The differences between it and the above two methods are very small.

• ∆NS = ∆MD * Sin((I1+ I2)/2)*Cos((A1+ A2)/2)

• ∆EW = ∆MD * Sin((I1+ I2)/2)*Sin((A1+ A2)/2)
• ∆TVD = ∆MD * Cos((I1+ I2)/2)*Cos((A1+ A2)/2)

Balanced Tangential
The balanced tangential survey calculation method is essentially the
Minimum Curvature method with RF=1. It is considered to be the least
accurate of these 4 methods.

• ∆NS = ∆MD/2.0 * (Sin(I2)*Cos(A2) + Sin(I1)*Cos(A1))

• ∆EW = ∆MD/2.0 * (Sin(I2)*Sin(A2) + Sin(I1)*Sin(A1))
• ∆TVD = ∆MD/2.0 * (Cos(I2) + Cos(I1))

Inclination Only
The inclination only method is included in COMPASS to handle
inclination-only measurement tools like TOTCO. It calculates vertical
depth the same as Radius of Curvature or Minimum Curvature, but does
not calculate the North and East dimensions.

Vertical Section Origin

The vertical section is the plane on which the wellpath trajectory is
projected for graphical purposes. The vertical section can originate at
either the slot location (left) or site reference point (right) as shown in
the diagram displayed

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below:

Coordinate origin
If the local coordinate system starts at the Site Centre (default), there is
one coordinate system for the entire site and each slot has different start
coordinates.

If the local coordinate system starts at the Slot, within the Site each Slot
has its own one coordinate system which has a starting coordinate of 0
East 0 North.

NOTE:

If you set the local coordinate origin to slot, survey and plan tie-
on coordinates do not inherit the well coordinates, tie-line N/S
and E/W coordinates will both be zero.

Compass calculates anti-collision correctly for either method but the

Site method is recommended. Before you start entering surveys and
plans you must have the correct setting.

Walk/ Turn Rate

COMPASS provides two methods of calculating walk (aka turn) rates
between any two points on a wellpath. The most commonly used
method uses the Along Hole Depth interval (MD). The second method
called Horizontal Dogleg (HDL), uses the along hole depth interval
projected onto a horizontal plane:

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• MD Turn rate = dogleg base length x change in direction /

change in measured depth.
• HDL Turn rate = dogleg base length x change in direction x
sin((I1 + I2) / 2) / change measured depth where I1 is the start
inclination I2 is the end inclination.
NOTE:

Dogleg base length is set in the Units Editor.

The following graphic depicts both MD and Horizontal Dogleg

Projection for Calculating Turn Rate:

Company Wellpath Types

Each Company can have a selection of different Wellpath types that are
a set of wellpath labels or type names with a designated colour. Once the
list is created, a wellpath type can be assigned to a wellpath in Wellpath
Setup. Wellpaths can then be selected for anti-collision scans based on
the type. For example, you cannot include Plugged and Abandoned
wells in your Anti-Collision scan.

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The following graphic depicts the Company Wellpath Types Editor

window:

Use the picklist

to select a colour
for each wellpath
imply type type
ellpath type
ames into the
preadsheet

Other Examples of Wellpath Types

• Producing Well
• Injection Well
• Plugged and Abandoned
• Lateral Wellbore
• Pilot Hole
In addition to anti-collision offset well filtering, you can use the
wellpath types in live graphs and wallplots to colour offset wells by
type.

Company Survey Tool Editor

A survey tool is an instrument that is used to measure the wellbore’s
position using inclination and azimuth measurements followed by
survey computation or by directly integrating inertial positions. Survey
tools are used in COMPASS to describe the error characteristics
associated with the tool. The tool’s error characteristics are used to
calculate the magnitude of measurement uncertainty about the
wellbore.Each survey instrument has several sources of error due to the
survey mechanism itself, the environment, or data processing methods.
A collection of these error parameters is called an error model.

The Survey Tool Editor enables you to define survey tool error models
in a Company’s COMPASS setup. These tools should be defined when
COMPASS is initially implement in a Company. Once defined,
checked, and approved Company Setup should be locked to prevent
error model parameters from being changed. Note: You cannot edit
survey tools while the Company Level is locked. To edit the survey tools
first unlock the Company Level in Company Set-up.

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COMPASS enables you to define several survey tools with different

error models. Generally, every survey tool operated at one or more
different conditions should have an error model defined in COMPASS.
These tools should have logical names so they can be intuitively selected
from the Survey or Planning module and the Survey Program editor.

The following graphic displays the Survey Tool Editor window:

Hide Survey Tools that

Assign a particular tool to be
List of Survey Tool are no longer used by
default for Plans and Surveys
Names and Descriptions Company but need for
historical calculations

List Type defines the Convert an error model

survey mechanism. This from Systematic Ellipse
is a useful feature for Parameters to equivalent
filtering from a large ISCWSA terms
selection of tools
Toggles enable Tool
Error Type to be
selected

Save new tool or apply

changes to existing tool.
This may update error Delete un-used Survey Export current survey tool Import enables new
surfaces of wellpaths Tools from Company List error model to a transfer file survey tool error models
with definitive paths to be imported from a
using this tool transfer file

The Survey Tool Editor enables the following functions:

• Add New Survey Tool Error Model.

• Update existing Survey Tool Error Model.
• Export Survey Tool Error Model to transfer file.
• Import Survey Tool Error Model from transfer file.
• Delete Survey Tool Error Model.
• Designate a Default Survey Tool, generally this should be the least
accurate tool.
• Hide a Survey Tool no longer used by the Company but linked to
historical survey data.

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To create a new tool:

1 Enter a unique name for the survey tool. You can use the same
name to define the same tool in another company.
2 Enter a Description of the tool (Max. 29 characters).
3 Define the error model you expect from the tool or as specified by
the survey contractor.
4 Click SAVE to include the new tool in the list.

To update an existing tool:

1 Select the tool you want to edit. The parameter field displays the
data for that tool.
2 Make any required changes.
3 Click SAVE.
4 If the Survey tool is used by any Definitive Wellpath definitions,
you are prompted to update those paths to recalculate their
positional uncertainty. If the error model parameters have changed,
click Yes when the warning prompt appears. If only the name or
description has changed click No.

To delete a survey tool:

1 Click the tool you want to delete.

2 Press DELETE. You can only delete tools that are not used by
COMPASS. If a tool you want to delete is used by any Definitive
Path, COMPASS displays a warning message that provides
instructions for removing any links to the tool defined in Surveys or
Plans. It can be difficult to locate all references for a tool.

To export a survey tool:

Export survey tools allows you to transfer tool data between companies
and systems.

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1 Select a tool from the Survey Tools list by clicking on it.

2 Click the EXPORT Button.
3 Enter the filename to create. The default filename is
TOOLNAME.IPM (Instrument Performance Model) in the
COMPASS/Output directory.

To import a survey tool

Import survey tools allows you to have a common set of tools sites
within a company.

1 Make sure you don’t have a tool selected in the Survey Tools list.
2 Click the IMPORT button.
3 Enter the directory and select the filename to import. These file
names should have an extension of .IPM.

Tool Properties
Short Name - Enter a short character code for the instrument type. This
code should uniquely identify this tool within the customer.

Description- Enter more text information on the application of this tool/

instrument.

Default Tool- Check one tool to be the default tool characteristic for any
plans or surveys that do not have tools assigned. It will also be the
default tool for any newly created plans or surveys.

List Type - Select one of the survey tool types for this instrument. This
will help sort the pick-lists for selections.

Hide in Lists - You can shorten the tool lists presented to the user by
hiding the tools that are not used in this operational area.

Convert from Systematic to ISCWSA Tool

This is a simple utility available when a Systematic Ellipse defined error
model is currently selected in the Tool list. It converts an error model
from terms defined by Wolff & de Wardt coefficients to equivalent
ISCWSA terms. After the conversion, all Wellpaths containing surveys
referenced to the converted tool in their Definitive Wellpath description
will have their error ellipse automatically recalculated.

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Diagnostics
For the ISCWSA survey error model, you can generate a diagnostics file
in the c:\TEMP directory. It is called SE***.TXT and contains
intermediate variables used in generating survey errors at each station.
This information may be used by a survey specialist to compare results
generated from Compass against known or predicted results. It is not
advised to keep this option turned on because it will slow down
operations and very large diagnostic files will be created.

Survey Tool Error Models

A survey tool error model describes how wellpath positional uncertainty
is calculated. When you run Anti-collision, COMPASS uses the error
calculated around each wellpath based on the error model defined and
the survey tools used.

For a particular tool, you only need to enter parameters for the error
model selected. For example, if the model is error cone, you do not need
to enter error values for the Systematic Error, ISCWSA or Inclination
Cone of Error Grid.

The four supported error models are:

• Error Cone. Enter the rate at which the error cone expands per 1000
units of measured depth.
• Systematic Error. Enter 6 coefficients for the survey instrument
components of error.
• Inc/Error Grid. For a range of inclinations you can enter a different
error cone expansion rate.
• ISCWSA. An extensible survey error modelling system with
configurable error terms and weighting functions.
You must assign a survey tool to the most appropriate error model with
accurate parameters. This information is most commonly provided by
the survey contractor. You should be able to email, phone or fax any
survey contractor and request precise details of the error model for a
particular tool. Otherwise, you can find descriptions of many survey tool
error models on the Internet on websites for Sperry Sun, SDC, Anadrill,
etc.

In contrast, some Operators (e.g. BPA, Shell) decide what the error
model and parameter values are for a tool. This assumes some form of
testing or statistical treatment of available survey data measured by that
tool.

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Regardless of where the information is obtained, definition of a survey

tool error model is critical. A COMPASS anti-collision scan is only as
good as the survey tool error model itself.

Cone of Error
This model assumes an error sphere around each observation. The size
of the sphere is computed based on the formula below. The model is
empirical and is based on field or test observation comparisons of
bottom hole positions computed from various instruments.

RADIUS AT CURRENT STATION = RADIUS OF SPHERE AROUND PREVIOUS

OBSERVATION + ((MD INTERVAL X SURVEY TOOL ERROR COEFFICIENT) /
1000).

The starting error around the wellbore is the well error plus the top
borehole radius (if defined).

Systematic Error Ellipse

This is based on SPE paper 9223 by C.J.M. Wolff and J.P. de Wardt first
published in the Journal of Petroleum Technology in December 1981.
The model is a statistical treatment of the distribution of errors caused
by internal and external influences. The paper demonstrates that the
major causes of error are systematic (that is, they happen consistently in
one vector direction) from one survey reading to the next. There are
error sources that are random, but they are assumed to be small and tend
to cancel out over a number of survey readings. The mathematical
methods applied by the paper have been an accepted industry standard,
but some of the example coefficient values and weighting are not current
with modern directional survey instruments.

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The following graphic depicts the Systematic Ellipse Parameter Entry

window:

Six Wolff & de Wardt Error Terms:

Activate interpolation of inclination

and azimuth errors for intermediate
inclinations within the Sample
Inclination range

Inclination/Azimuth Error Grid. If

populated overrides WdW
inclination and azimuth errors.

The Systematic Ellipse error model has six coefficients:

This error... Occurs because...

Misalignment There is an error in the instruments’ centralisation in

the borehole/casing. Misalignment affects both
inclination and azimuth and is derived from sensor
axis and tool centraliser misalignment.

Relative Depth There is an error in measurement of along hole. Depth

error is derived from pipe tally measurement, stretch
for pipe tool runs, and wireline measurement error for
cable tool runs.

True Inclination There is an error in inclination measurement. This can

be caused from weight induced effects on pipe
running gear and is sensitive to inclination.

Compass Reference There is an error in referencing North. Declination for

magnetics or surface azimuth orientation for
gyroscopes - foresight.

Gyroscope Azimuth There is an error in gimballed gyroscope azimuth

readings caused by gimbal drift that increases
exponentially at higher inclinations (see Grid below).

Magnetic Azimuth There is an error in magnetic azimuth readings caused

by drillstring magnetisation. The error increases at
higher inclinations and east/west azimuth.

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Because of the variation of error parameters along the X, Y, Z vectors,

the resultant shape of the error surface is an ellipse as projected in 2D,
an ellipsoid as plotted in 3D. The orientation of the ellipsoid with respect
to the wellpath is dependent on the relative change of Wellpath
Inclination and Azimuth.

The systematic error model coefficients and their weighting factors are
recognised as being inadequate for modern solid state magnetic
instruments and for rate gyroscopes. COMPASS provides the
inclination/azimuth error grid to help define error models for more
complex instruments. Again, the inclination and azimuth error
characteristics for each inclination angle range can be provided by the
manufacturers and inserted into the tables.

These error characteristics are substituted for the respective inclination

and azimuth error of the Wolff & de Wardt coefficients, therefore the
True Inclination Error, Drillstring Magnetisation, and Gyrocompass
Azimuth coefficients are greyed-out. The inclination weighting factors
would not be applied, because of the relationship defined in the table.
The Interpolate toggle enables error values to be determined for
intermediate inclinations between the ranges entered.

Inclination vs. Cone of Error Grid

For a range of inclinations you can enter different error cone expansion
rates. The example below shows that from 15 to 35 degrees inclination
the cone of error expands at 5.0/1000ft (or 5m/1000m) of measured
depth.

The graphic below displays the Inclination Cone of Error dialogue:

Enter end of range for the

error term. Note: grid starts at Enter the expansion rate
0 deg per 1000 units

Interpolate
By setting the interpolation setting to on, the error values are
interpolated for intermediate inclinations. Otherwise the error value is
treated as discrete between sample inclinations.

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For example, if the following errors were entered:

Sample Inc Error/1000

10 1

20 2

If the error was determined at 15 degrees inclination:

• Without interpolation would yield a cone of error of 2/1000.

• With interpolation would yield a cone of error of 1.5/1000.
In both cases, the values below 10 degrees would be 1/1000 cone of
error and above 20 degrees would be 2/1000 cone of error.

ISCWSA
The ISCWSA Tool Terms grid is used to describe a dynamic number of
error terms for any type of survey instrument. In this grid, the error value
and weighting formula may be entered as well as the vector direction
and treatment at the survey tie-on.

The following graphic depicts the ISCWSA Grid:

The contents of the ISCWSA tool term grid are roughly equivalent to the
format of the Instrument Performance Model (IPM) file used for
importing and exporting. The IPM file contains a number of lines which
represent individual error terms for the survey instrument. These include
instrument reading, depth measurement, instrument barrel-hole/collar
alignment and external reference and interference terms.

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File format
The file contains a number of lines containing 5 to 7 strings or values
separated by an accepted separation character (Comma, semicolon, Tab,
space). Error term lines are identified by their first character being
alphanumeric. Comment lines may be included, they are identified by
their first character being non-alpha (i.e. Space # / )

NAME - Give the error source an unique name unless you want it added
on/to the same source of error from another or the same tool. See Tie-on
definition to clarify.

VECTOR - This sets the vector direction for the error source

• A - Azimuth error (WdW).

• B - Azimuth bias
• D - Depth error (WdW)
• E - Depth error (ISCWSA)
• F - Depth bias (e.g. Wireline stretch outrun)
• I - Inclination error (highside)
• J - Inclination bias (uncorrected sag)
• L - Lateral error (error at 90/270 toolface equivalent to azimuth
error/sin(inclination))
• M - Misalignment – forms a disc about the wellpath.
• N - Inertial error – forms a sphere about the wellpath.

VALUE - The number associated with the error source. Care must be
specified to what confidence level and unit type for the error value. The
confidence level for the uncertainty is stated in the Customer Setup. To
get extra precision for this column data, change the ‘Coefficient of
Friction’ unit type in the Units Editor.

TIE-ON - This determines how an error source is tied onto sources of the
same name from other tools.

• R - Random, error is added by RSS (Root Sum Squares) from

station to station.(e.g. Misalignment for rotating MWD)
• S - Systematic, error is added directly from station to station run
but added randomly at tie-on.
• W - Well, error is systematic throughout the well (e.g. Reference
error)
• G - Global, error is systematic across a number of wells. (E.g.
Crustal Declination error)
• N - Not used in error accumulation, (this term is used as an
intermediate calculation)

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UNITS - The following unit selections are available:

• ‘ ‘ - No unit conversion.
• M – Metres to feet conversion, equivalent to MTF in the
formula.
• IM – Inverse feet to metres conversion, equivalent to 1/MTF in
the formula.
• D – Degrees to metres conversion equivalent to DTR in the
formula.
Other unit types may be given but are not interpreted.

FORMULA - The formula is the calculation for each error term and is
given as a formula that can be parsed like Excel. Typical arithmetic
conventions can be used like: * / - +, power: X^Y,trigonometry: SIN(),
COS(), TAN(), ABS() etc. The capabilities of the parser are better
shown by the examples below.

The following names may be substituted in the formula:

• AZI - Azimuth of current station

• AZM - Azimuth from magnetic north (used for magnetic tools)
• AZT - Azimuth from true north (used for gyro tools)
• AZE - Azimuth error for tie on from previous tools (used to
determine reference error)
• INC - Inclination of current station
• TFO - Toolface angle - The instrument rotation (i.e. alignment of
Y accelerometer with highside)
• TMD - Measured depth from init point.
• TVD - Vertical depth from init point.

The program loads Magnetic Field Data:

• MTOT - Total magnetic field strength given in nanoTeslas (i.e.

50000) Note: Magnetometer bias errors must be same units
• DIP - Magnetic field dip angle from vertical.
• LAT - Current latitude.

Gyro continuous values:

• AZE - Azimuth error before tie-on

• INX - Inclination error before tie-on
• DMD - Measured depth from start of this survey tool (i.e.
continuous mode drift terms)
• EROT - Earth’s rotation rate = DTR * 15.041 / Cos(Latitude)

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Note: Gyro bias drift values should be entered in degrees/hour.

Constants:

• MTF - Metres to feet - the model evaluates in feet.

• DTR - Degrees to radians - use this when Error is given in
degrees
• GTOT - Gravity total (9.81 m/s^2)
• THO - Thousandths (=0.001)

RANGE - Check this box to specify a range for the tool. The error term
can be made specific to a range of inclination angles. Min (optional),
Max (optional)

Example #1

# Model for Wolff &deWardt, Poor Magnetic. This example shows use
# of a bias error term MAGB.
#Name Vector Tie-On Value Formula
DEPTH D S 2 THO
MISAL M S 0.3 DTR
TINC I S 1 DTR*SIN(INC)
REF A S 1.5 DTR
MAGE A S 5 DTR*SIN(INC)*ABS(SIN(AZM))
MAGB B S 5 DTR*SIN(INC)*ABS(SIN(AZM))

Example #2

# Model for Gyro Continuous Tool (GCT)

# This model assumes changeover at 15 degrees
#Name Vector Tie-On Value Formula Min Inc Max Inc
DEPTH D S 2 THO
MISAL M R 0.1 DTR
TINC I S 0.06 DTR
ASFO I S 0.0016 ABS(TAN(INC-20*DTR))
# two reference errors one for each tool mode
REFA S 0.51DTR*COS(60*DTR)/COS(LAT) 0 14.999
REFA S 1.0 AZE 15 99.999
# two gyro bias errors one for each tool mode
GBLL S 0.8 DTR*DMD*TAN(INC)/4800 0 14.999
GBHL S 0.15 DTR*DMD/4800 15 99.999

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Field

Geodetic System

System Datum e.g. MSL

Wellpath Datum e.g. RKB

Geomagnetic
Model

Well Reference Point e.g. ML

A Field is a group of sites or well locations in the same geodetic system

aligned to either Grid North or True North. You use the Geodetic
System to calculate grid convergence and scale factor at any point in the
field and to perform local to map to geographic coordinate conversions.
A Field also has a System Datum, the name given to 0 TVD for the
Field. Typically, this datum is Mean Sea Level. Within the Field,
wellpath data can be referenced to the Field Datum, individual Wellpath
Datums or to the Well Reference Point which is typically the mudline.
For the Field, a Global Geomagnetic Model is selected to determine
magnetic declination at any location and at any time in the Field.

If there is any chance that two or more wells can collide, include them
in the same field. You can always perform Anti-collision scans between
wells in the same field. There is a Close Fields algorithm in Anti-
Collision that you can use to detect wells from other Fields that extend
within 25km of the current field.

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Field Setup
The following graphic depicts the Field Setup window:

Compass is shipped with a default set

of Geodetic Systems. For a Field,
choose the appropriate system from the
default set or add a custom geodetic
file. If uncertain use Flat Earth
(Geodesy turned off). Geodetic systems
are used to convert local coordinates to
equivalent Map and Geographic
coordinates (e.g. UTMs, Latitude &
Longitude)

Sets TVDs stored in database to be

relative to Wellpath Datum, Field Datum
or Well Reference Point

System Datum name can be selected

from picklist (MSL, LAT) or typed in
using keyboard.
Lock Data to prevent unplanned/
unauthorised changes to the Field
settings

Wellpath local Northings and Eastings can be The selected Geomagnetic Model is
made relative to the Slot, Site reference point used to calculate the Magnetic Field for
or a selected Site within the Field a given location and time

Field
The name that uniquely identifies the field. This name appears in the
Open Window in which you select different data sets.

Location & Block

Two lines for additional information about the field. This information is
not used by COMPASS but appears in the reports.

Geodetic (Geographic Reference) System

You must select the correct geodetic system before computing grid
convergence or performing geodetic conversions from latitude and
longitude to equivalent map Eastings and Northings. For more
information on Geodetic systems see the section in the Tools section of
this manual.

Geodesy is the science of measuring the earth’s surface. The Earth is

round and maps are flat. A geodetic system enables you to convert
geodetic coordinates (angles on a round earth - latitude / longitude) to
map coordinates (distances on a flat map - easting / northings). To do
this you must know the system, the ellipsoid, and the zone.

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System
A geodetic system is one or more map projections covering adjacent
parts of the globe. A system can comprise one or more zones. If you do
not know the geodetic system for your area or if you have no need to
convert between geodetic and map coordinates, select Flat Earth. By
selecting Flat Earth you disable conversion between geodetic and map
coordinates throughout the Field.

Ellipsoid
A mathematical model that represents the shape of the earth. The earth
is not a perfect geometric shape; it is an irregular slightly flattened
sphere - a geoid. We cannot compute geodetic conversion on a geoid so
we assume the earth is an ellipsoid. Because the earth’s surface is
irregular, different shaped ellipsoids best fit different parts of the globe.
The size and shape of the ellipsoid varies depending on part of the globe
being mapped.

Zone
A geodetic system can one or more zones, each zone maps a different
area. It is to the Zone’s origin to which Map Northings and Map
Eastings refer.

Custom Geodetic Files

COMPASS is shipped with a standard set of Geodetic configuration
files (*.GDF). These config directory files have a simple format that
enables clients or Landmark Support Engineers to create custom formats
to meet the requirements of a client in a particular area. For example
custom formats recently released to clients include the German/Austrian
Bessel system, Gauss-Kruger projection for the Caspian Sea, and a
Lambert Tangential projection for Bangladesh. If a Geographic
reference system is required by a client, it can be built and made
available within Compass.

From our Landmark FTP site at ftp://ftp.lgc.com/pub/products/

COMPASS/geodetic_files/, you can download existing custom *.GDF
files or the GDF_FILE.DOC that explains how to customise your own
GDF file. A User Name and Password is required for the FTP site and is
available for current M&S clients, contact your local Landmark Support
office for more details.

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Chapter 4: Data Structure

Vertical System Datum

The vertical system datum is the name given to zero height or depth for
the field. Select a name from the picklist (MSL or LAT) or type a new
name.

Depths Stored To
You have the option to reference True Vertical Depths to either the
Local Datum, Field (System) Datum or the Well Reference Point. This
setting applies only to vertical depths - measured depths are always zero
at the wellpath datum. Note: if you select to use Well Reference Point,

Sets TVDs stored in database to

Sets TVDs stored in database to be
be relative
relative to Wellpath
to Well Reference Datum,
Point, e.g. e.g.
RKB, DFE
mudline

Sets TVDs stored in database to

be relative to Field Datum, e.g.
Mean Sea Level

Sets TVDs stored in database to

be relative to Well Reference
Point, e.g. Mudline

the System datum is still used for defining Site and Wellpath datum
heights.

• Local Datum - Zero TVD is at the wellpath datum, i.e. Rig Floor.

• System Datum - Zero TVD is at the field's Vertical System

Datum. Zero measured depth is at wellpath datum.

• Well Reference Point – In this system, the depths are stored

relative to a fixed point that will not move if the rig changes. The
well reference point is the last position where the wellbore can
be located using land surveying techniques, e.g. Seabed
(mudline) or ground level (wellhead). The viewing datum is
stored in the Wellpath Set-up and should be the rig floor of the
rig currently drilling on the well. With this method, surface
Surveys and Plans are tied to the Well Reference Point, not the
Wellhead.

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Local Coordinate System

Centred on
You can have a local system (N/S E/W) for each Site or you can
nominate one of the sites to be the origin for the entire Field. If you
decide on one coordinate system for the field you must select one of the
sites from the Field Centre based upon Site list.

NOTE:

Because each site has a different convergence angle, if you opt for
a Field Centred coordinate system, local north must be set to
Grid.

Site Centred Referencing Field Centred Referencing

0N, 0E
3233N,
2877E

0N, 0E

0N, 0E 0N, 0E
-5122N,
4533E
Local Coordinate System Base on Local Coordinate System Based on
Site Field

Geomagnetic Model
Select the Geomagnetic Model you want to use to compute components
of the Earth’s magnetic field. The list consists of geomagnetic models
configured for your COMPASS system.

The following models are available:

• IGRF International Geomagnetic Reference Field

• WMM World Magnetic Model
• BGGM British Geologic Survey Geomagnetic Model
There can be multiple models of the same model type designated with
the first year that model is applicable. For example, IGRF90 is
applicable before 1995 but not earlier than 1990. IGRF95 is a predictive

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Chapter 4: Data Structure

model for 1995 or greater. The IGRF and WMM models are publicly
available off the internet and therefore installed by default with
COMPASS. These models are updated every 5 years. Configuration
files for the years 2000-2005 are currently available off the Landmark
FTP Site or from your Landmark Support Engineer.

The BGGM models are available by private subscription from the

British Geologic Survey in Edinburgh. They are updated annually. If a
client can provide proof that they have a license from the BGS,
Landmark can supply additional configuration files (BGGMxx.GAM)
to support their use in COMPASS. See the Tools section on
Geomagnetism for further information.

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Site

A Site is a collection of one or more Wells all referenced from a local

coordinate system centred on the site location. A site can be a single land
well, an offshore sub-sea well, a group of wells drilled from an onshore
pad, or a group of wells drilled from an offshore platform or template.

For land wells, the site would initially appear to have little application
except that COMPASS expects the location to be defined here as well as
positional uncertainty and the site datum. The Well structure in
COMPASS would normally have the same name as the site. If the Site
is a platform or template, each slot would be a well.

To define the Site location, you can give the Site Centre Map or
Geodetic coordinates and assign an elevation above a System or Field
Datum. Sites can have drilling targets that can be selected by one or
more wellpaths.

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Site Setup
The following graphic depicts the Site Setup window:

The Site reference point. This local

coordinate origin has coordinates 0 N/S,
0 E/W. May be defined by either of the
four location methods

Positional uncertainty dependent on the

survey method used to map the site
location e.g. GPS.

Default vertical reference datum for the

site. Each wellpath may define its own
datum

Click here to prevent

unauthorised changes to
Convergence Angle is the difference Survey errors start accumulating at the mudline Site details
between True North and Grid (Map) North. for offshore wells. This value is important anti-
If unsure, calculate and seek the advice of collision error ellipse calculations
your survey focal point

Site
The name that uniquely identifies this site. The Site name should refer
to the location, not the drilling rig. Rigs are mobile, place names are not.

Location
Additional information about the site.

Centre Location
COMPASS uses the Map Coordinates values to compute the distance
between two sites during field level anti-collision. You can enter Map
Coordinates directly or convert them from latitude and longitude.

Choice Description

None If selected, anti-collision between sites is

disabled

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Choice Description

Map Coordinates The map coordinates of your location based

on the Geodetic System selected in the Field
Setup window. These are essential if you
compute field level anti-collision. The map
coordinate units are set in the Unit System.
You can check your existing Map Coordinate
units by clicking in a Map Coordinate field
and reading ‘Units:’ in the Status Bar (lower
right-hand corner).

Geographic Coordinates The geodetic coordinates of your location

based on the Spheroid selected in Field Setup
To enter global coordinates you first select a
geodetic system in Field Setup. The default,
Flat Earth, equates to no geodetic system.

From Lease Lines Lease line coordinates are distances from the
boundaries of a leased area. Enter site centre
as a distance from either North or South line
and from East or West line.

The graphic below depicts Lease Line coordinates. Two site centres are
indicated, one as a distance from a West and North line, another from an
East and South line:

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NOTES:

• COMPASS does not use lease line coordinates to compute anti-collision

between two sites, this requires map coordinates.
• You can reference the Site Centre’s Map or Global Coordinates to Lease
Line Coordinates by putting in the Lease Line values, but make sure to set
the radio button back to Map or Global Coordinates.

Water Depth
For Vertical Depth Reference Systems set to Local or System, this
distance is added to the wellpath datum to obtain the depth at which
survey errors start to be calculated. Otherwise, this value is used as the
default for the Well Reference Point in Wellpath Setup.

The following graphic depicts Datums and Water Depth:

In the example above, the name given to Field Datum is ‘Mean Sea
Level’ (MSL). The water depth is 320 ft. and the rig's Drill Floor
Elevation (DFE) is 80 ft. above MSL. By setting Water Depth to 320ft
and the Wellpath Datum to 80 ft., you start accumulating survey errors
from the sub-sea template and not from the drill floor.

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Location Uncertainty
The Site Survey Method accuracy to which the site has been positioned
or the uncertainty of the local coordinate origin relative to map or
geodetic coordinates. For example, a floating drilling rig can be
positioned with an accuracy of 1-2 m and due to wind and wave
movement, oscillate around the mean position. If drilling over a sub-sea
template you should include the position uncertainty of the template, not
that of the vessel. When spudding an exploration well, this uncertainty
should be included as it is used during anti-collision calculations
between wells drilled from different sites.

Slot Radius
The radius of the drill bit for the first hole section. This value is added
to all errors calculated for wellpaths in a site. For example, a drill bit of
26" diameter has a radius of 1.1’. This entry is not mandatory, it has been
added to be compatible with some versions of DOS COMPASS. If a
value has been entered it is used.

The slot size displayed in the Template Editor can be changed by

defining a value of TBR. If TBR is 0, then the Template Viewer displays
a slot with a default radius of 1ft.

Error Surface Origin

When used by the Anti-Collision module, the Position Uncertainty and
Top Borehole Radius parameters can be used in different ways.
Generally, when calculating positional uncertainty, the radius of the
error ellipse at water depth/ground level is the positional uncertainty
plus top borehole radius.

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The following graphic depicts site parameters used to calculate

positional uncertainty:

When performing anti-collision scans between wellpaths in the same

site, positional uncertainty of the site is not added to the initial error
surface radius.

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The following graphic depicts Intra-Site Anti-Collision:

When performing anti-collision scans between wellpaths in different

sites, the positional uncertainty of each site is added to the initial error
surface radius of each wellpath.

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The following graphic depicts Inter-Site Anti-Collision:

Azimuth Reference
You can align the site’s local coordinate system to either True or Grid
north. Depending on your selection, the north axis of all the sites in the
field is aligned to either true or grid north and all surveys corrected
accordingly. See section in Field Setup on True, Grid, and Magnetic
North.

Convergence
Grid Convergence (GC) is the angle from True North to Grid North, also
called Map North. In the Northern Hemisphere, a positive value of GC
indicates that Grid is East of North, a negative value of GC indicates that
Grid is to the West of North. Press Calc to compute this angle using the
Geodetic System you specified in Field Setup and the coordinates
specified in Centre Location.

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Site Datum
Specify a default elevation for the site above the Field Datum. You can
select one of the datums previously entered in the Datum Table or if
creating a new site, you can enter the Elevation. This is then added to,
and can be edited in, the Datum Table.

When you create a new wellpath the site datum is inherited but can be
changed as necessary.

Site Editors
Site level data is available and can be shared or used by all Wells and
Wellpaths in the Site. This data consists of Templates, Targets, and
Datums. These editors are described in the Tools section of this manual.

True, Grid and Magnetic North

True North
Imagine a line extending from you to the North Pole. This is a line of
constant Longitude that points to true north.

Grid North
On a map, a line joining two points with equal Easting coordinates
points to grid north. By representing the spherical earth on a flat map the
distortion introduced means that grid north does not point to true north.
The angle from true north to grid north is called grid convergence.

Magnetic North
A magnetic compass aligns itself with the horizontal component of the
Earth’s magnetic field, generally pointing to the Magnetic North Pole.
The angle from True North to Magnetic North is called magnetic
declination. Declination affects magnetic survey readouts that must be
corrected back to grid or true north. Magnetic declination is sometimes
referred to as the magnetic variation or the magnetic compass correction
as the bearing to Magnetic North varies with location and time.

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The following graphic depicts Norths Reference custom in Northern and

Southern Hemispheres:

NOTE:

These diagrams are schematic. The direction and magnitude of

magnetic declination and grid convergence depends upon the
location.

In COMPASS, the convention for displaying convergence in the

Northern hemisphere is that positive values are to the East (right) of
True North, negative values are to the West (left) of True North. South
of the equator, this convention is reversed.

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The following diagram depicts conventions for the sign of grid

convergence in northern and southern hemispheres and west/east of the
geodetic zone’s central meridian.

Com pass - Sign of Grid Convergence

Central
M eridian
G rid = True - Conv G rid = True - Conv
G T T G
- +

Equator

T G G T

+ -
G rid = True - Conv G rid = True - Conv
500,000 m

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Well

A Well is simply a surface location, referenced from the Site local

coordinate system. A well can be located at the site centre or offset some
distance N/S - E/W from the site centre. If a geodetic system is
configured for the Field, equivalent Map Coordinates are calculated
automatically. If a template has been created for the Site, a Well can be
assigned to a slot in that template. In which case, the well location
assumes that of the slot. For Land wells, a Site and a Well are often the
same thing. So, local coordinates from the Site for the Well are set to 0
N/S, 0 E/W with the names being identical.

A Well can have one or more Wellpaths assigned to it. For example, the
original wellbore with one or more sidetracks tied on to it at different
lick off depths. In Compass, any wellpath trajectory can be traced
directly from its TD back to the Well surface location.

Well Setup
The following graphic depicts the Well Setup window:

Well A1 assigned to slot A1

using drop down picklist.
Well Northings & Eastings
automatically taken from Slot
location within Template. Map
coords displayed for reference.

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Well
The name that uniquely identifies this well.

Description
Additional information describing the well. This information appears in
the reports if entered.

Wellhead Location
One of two methods for defining well location. You can define the well
surface location by entering the N/S E/W directly or by selecting a Slot
if you have set up a template. For either method, if a geodetic system is
defined for the Field, equivalent Map Coordinates and Geographic
Latitude and Longitude are automatically calculated.

Map Position of Wellhead

The wellhead position can be defined in map coordinates. Enter the
Easting and Northing of the wellhead and the local coordinates are
calculated from the site centre. If the slot is defined or the local
coordinates entered, the map position is calculated for information.

Well Position Error

A position error can be associated with the well location. This error is
added to all errors generated on wellpaths in this well. Do not confuse
this error with site position error. The well error is designed for special
cases, for example when there are a number of wellheads in close
proximity to each other (grouped in the same site) but not connected by
a template. The well error in this case is the error in measurement of one
well relative to others, but not the error in the group’s location, which is
the site position error. It is recommended that you leave the Well
Position Error at zero for template wells.

Well Reference Point

The Well Reference Point (WRP) is a permanent, recoverable, fixed
point in the well. If its use is defined for the vertical reference system
within Field Setup, then all depths and co-ordinates are stored relative
to this point. Otherwise, the WRP area within Well Setup is not
displayed. The WRP is usually at the well's position at seabed for
offshore installations or at ground level for land installations. This
location will be used as the tie-in point for the first survey and plan on
this well.

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The following graphic displays the Well Reference Point parameters

area in Well Setup which is only displayed when WRP is set for use
within Field Setup:
Depth below Field Datum e.g. Mean Sea Level

Define tie-on MD, location and well orientation at the WRP.

Vertical Distance Above/Below System

Enter the vertical distance of the point above or below the system datum.
For offshore installations the distance is positive below mean sea level.
For land installations the distance is positive above mean sea level.

Non Vertical (curved conductor/slant rig)

If the rig is vertically positioned above the wellhead then all you need to
enter is the vertical distance above /below system. If the rig is offset
from the wellhead for various reasons, you need to enter the information
below to define the offset location of the well reference point.

Additional Measured Depth at WRP

If the wellbore is non-vertical at the WRP then the along hole distance
from rig datum to WRP is longer than the vertical distance. In this case,
enter the additional measured depth, which is usually less than 1m for
curved conductors. This additional distance will not change if the rig
elevation change.

Offset from Wellhead North/East

Enter the horizontal distance from the wellhead (on fixed installation) to
the WRP on the seabed/ground.

Inclination and Azimuth

Enter the wellbore inclination and direction at WRP, if it is non-vertical.
Azimuth is to the north reference (True or Grid) chosen in Site Setup.

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Wellpath

A Wellpath is a borehole, which is one or more contiguous sections of

wellbore traceable up to the surface location. It could be an original well
drilled from surface or a sidetrack kicked off from a known depth from
a parent wellpath. If a Well has an original hole and two sidetracks
drilled from it, that Well has three Wellpaths defined in COMPASS.

When using COMPASS there is only one active wellpath whose name
appears in the Status window. The Wellpath category allows you to file
multiple Surveys and Plans in their respective boreholes. When opening
Surveys or Plans, you are only shown names of items in the current
wellpath.

A Wellpath is defined by its Definitive Path. The Definitive Path is

defined as the most accurate guess to its actual trajectory during the life
of the wellpath. At the Planning stage, it consists of the current
directional well plan (Principle Plan in COMPASS), while drilling it
would be dynamic consisting of a combination of the most accurate
surveys available at any time. A planned sidetrack would consist of
actual Surveys down to the KOP plus the Plan for the sidetrack.

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Wellpath Setup
The following graphic depicts the Wellpath Setup Dialogue:
If the Wellpath is the original wellbore, there is no parent wellpath (not tied). If the Wellpath is
a sidetrack, then you select the parent and enter the KOP off of it.

Wellpath type enables wellpaths of the

same type to be identified on plots or
filtered in an anticollision scan.

Select the current datum height from the

Site datum list. May be changed later with
depths being shifted where appropriate

Vertical Sections may be defined at

different vertical depth intervals. The
surface origin may be the Slot, Site Centre
or User Defined

Each line of the vertical section may have The Wellpath contains information regarding the
an orientation selected from: strength and orientation of its local magnetic field. This
can be calculated automatically after a save or
• calculated bottom hole location manually calculated or entered here
• a target location
• user defined angle

Wellpath
Enter a name to uniquely identify the wellpath or sidetrack.

Description
Additional information about the wellpath.

Parent Wellpath
A wellpath must start from surface or be sidetracked from another
wellpath. If it is sidetracked, select the wellpath that contains its starting
point.

Sidetrack MD
The measured depth on the parent wellpath at which the sidetrack starts.
This depth is referenced to the new wellpath’s Depth Reference Datum.
Don’t use Sidetrack MD if the wellpath is the original wellbore (1st
wellpath of the well), Parent Wellpath will be No Tied.

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Vertical Section
Vertical section defines the vertical plane or planes to measure the well
displacement. The plane requires an origin and a direction. A number of
vertical sections may be defined and each one will start at a specified
vertical depth. Normally with single target wellpaths you need to define
only one. However, with multiple targets or major changes in direction,
multiple vertical sections will better represent the wellpath distances on
a section plot.

Vertical Section Origin

The vertical section dimension has a zero point that starts from an origin.

You can define the vertical section origin to start from one of the
following:

Start Description

Slot The vertical section originates at the current slot or well

coordinates.

Site Centre The point you defined as the site centre location in Site Setup.

User Enter the co-ordinates of the vertical section origin in the grid
as Start N/S and Start E/W. (i.e. sidetrack point). In this case
there may be several origin points to ensure continuity.

Vertical Section Angle

To determine the direction of the vertical section plane from local north
you enter one of the following:

Start Description

Bottom Hole The angle is calculated from the origin to the last survey point
Location in your definitive wellpath.

Target Select a target from the list of targets and COMPASS computes
the angle.

User Enter the direction of the vertical section plane from local
north.

Rig Name
Enter the name of the installation drilling or re-surveying the wellpath.

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Wellpath Type
Select a wellpath type to classify the wellpath. This is not essential but
can be useful when filtering wellpaths for anti-collision scans or
changing the wellpath colours by type in the graphics. See also Wellpath
Types and Offset Wellpath Selection.

Reference Datum
Select a vertical datum against which all measured and true vertical
depths are referenced. When you create a new wellpath by default, it
inherits the height of the Site Datum.

Relative Datum Shifting

COMPASS does enable a user to change the active Wellpath datum
height. This may or may not required that data, already entered for the
wellpath, have its depths shifted relative to a new datum. If the reference
datum is changed, you are asked ’Do you wish to shift data to the new
datum?’

Select:

Selection Description

Yes All depth information on this wellpath is converted to the new

datum. This is particularly useful if you have planned a well to
MSL/LAT before knowing the rig elevation, then the rig is
contracted and you wish to convert to the known DFE/RKB. It
also works well if you are planning a sidetrack with a new rig.
You can plan to the original RKB and then shift to the new RKB
once known.

No The datum is accepted but no depths are changed (say No if you

made a mistake in selecting the original datum, or datum was not
assigned in an import).

Magnetic Declination
Magnetic Declination is the direction of local magnetic north from true
north. Magnetic Declination appears on plots and reports and can be
calculated or entered directly. This area enables a user to enter the
magnetic referencing data for this wellpath’s operations.

Check the Edit Magnetic Field Data box to select this option if you wish
to change the automatically calculated magnetic data. If not selected
then the magnetic data is updated from the magnetic model when the

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wellpath is saved. The earth’s magnetic field changes with time so this
data has a time stamp. Press Calculate to use the Geomagnetic
Calculator with one of the predictive geomagnetic models.

If a more accurate local source of magnetic declination is available,

possibly from a nearby airport or government surveying body, you can
type it directly into the declination field. However, when reporting,
COMPASS refers to the configured geomagnetic model. You can
workaround this by creating a custom geomagnetic configuration file
that details the local source information.

NOTE:

The magnetic declination in COMPASS is generally not used by

engineering functions. It simply exists as a value that can be
reported and plotted as a Norths reference arrow. The exception
is for ISCWSA survey tool error models which may reference it.

Sample Date
The date used in the magnetic model to project the magnetic field. This
date may be planned (extrapolated) or historical (interpolated).

Field Strength
The magnitude of the magnetic field in nanoTeslas.

Dip Angle
The dip angle from horizontal of the magnetic field.

Declination
The direction of magnetic north from true north. The declination is
displayed on plots and reports. See True, Grid & Magnetic North for a
definition of declination.

Click OK to apply any changed settings. If the wellpath contained

surveys linked to ISCWSA survey tool error models, then the wellpath
will be recalculated as the ISCWSA model may reference magnetic field
strength, dip or declination.

Locked
Set the lock check box if you wish to prevent users from editing or
deleting this wellpath and associated data (Survey Program, Definitive

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Path, Casings, Formations, Annotations). If a Wellpath is locked, this

also fixes the offset well list and anti-collision interpolation settings.

Survey
A survey is a series of survey readings that:

• Have been observed in the same Wellpath (borehole).

• Have been observed with the same Survey Tool.
• Increase with measured depth.
If you have a survey in the original hole and an MWD survey in a
sidetrack and want to combine both surveys you first store the surveys
individually and then combine them by tying the sidetrack survey on to
the Definitive Path of the original hole.

Plan
A plan is the theoretical shape of a proposed wellbore. Each Wellpath
can have multiple plans. When you decide which plan you are going to
drill, mark that plan as the Principal Plan. (There is a check box on the
Plan Setup window for marking the plan the Principal Plan).

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The following graphic depicts the Plan Setup window:

Plan name & description

appears in reports Toggle here to make
Planned Trajectory
available to Definitive
Wellpath

Enter planned
Tie-on Point defines the sequence of surveys for
start location and the wellpath
orientation of the planned
trajectory

Plans can compose all or part of the Definitive Path when marked as the
Principal Plan.

Definitive Path
A Wellpath can contain several surveys and plans. When conducting an
Anti-collision scan, calculations are made not against individual surveys
or plans, but against the Definitive Path defined for each offset well. It
is important that the Definitive Path is updated with higher quality
surveys as they become available.

The Definitive Path should be the survey or combinations of surveys

that most accurately describe the wellpath shape. Each time you save a
Principle Plan or Survey you are asked if you want to add it to the
Definitive Path. In addition, you can change the composition of the
Definitive Path using the Survey Program editor.

For example, the first hole section can initially be surveyed by an MWD
tool. Once cased, a Gyro can be run over the same hole section. This

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could be followed by MWD for the next hole section then another final
Gyro survey.

Survey History - The Definitive Path Story

1st Hole Section 1st Hole Section 2nd Hole Section 2nd Hole Section
Open Hole Cased Open hole Cased - Final Survey
MWD1 Definitve Path Gyro 1 Definitve Path MWD2 Definitve Path Gyro 2 Gyro FS

MWD is the only MWD replaced by a MWD in next open hole Gyro run from surface
data we have, so it gyro survey. The gyro section tied-on to gyro replaces all previous
becomes the survey becomes the to form Definitive Path surveys to form the
Definitive Path Definitive Path Definitive Path

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Tools

In addition to the setup windows for each level of the data structure, you
commonly use a number of additional utilities and resources when
working with COMPASS. This section describes the use and theory of
a number of these tools.

Site Editors
Site level data can be shared or used by all Wells and Wellpaths in the
Site. This data consists of Templates, Targets, and Datums.

Site Template Editor

A template is an array of slot coordinates that define the surface/subsea
location of wells. The Site Template Editor is a coordinate generator that
provides an easy way to define slot template geometries. When you
define a template, you can enter single slot coordinates or, if the
template has a rectangular or circular slot layout, COMPASS can
automatically calculate the local slot coordinates for you.

A site can have more than one template defined for it, for example, a
collection of sub-sea wells or a platform that has had additional slots
attached to it.

When creating a well, you don’t have to use the Site Template Editor to
define the well location. You can type in the local coordinates directly.
However if slots are defined, you can select a start slot and assume the
calculated local coordinates of that slot.

The Template Editor uses two resizeable panes located in the same
Window: an Editor and a View. The relative sizes of each may be
adjusted by moving the separator bar. The Editor enables you to define
templates, and the View graphically portrays the template currently
selected and provides the usual COMPASS live graphics tools.

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The following graphic depicts the Slot Template Editor and View:

View/Select Templates Here

Define Template Properties Here

COMPASS supports three types of Templates:

Template Type Definition

Rectangular Row by Column slot spacing

Circular Radial slot spacing

Single One slot, such as sub-sea well or onshore

drilling pad

You can convert regular shaped rectangular and circular templates to

single slot templates if required. Note: this is not reversible.

For each type of template, you must enter a short name, a long name, and
the location of slot reference from the site centre. If Site is a platform
then coordinates are normally 0 NS, 0 EW. In the example above, the
Echo template has a short name E so that each slot is numbered E1, E2,
E3, and so on. You define the template geometry and then add it using
the Add button in the toolbar, modify it using the Save button, or delete
it using the Delete button. Existing templates may be selected from the

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picklist on the Geometry tab or selected using the mouse within the
View. Active templates are highlighted in red within the View.

After generating one or more templates you use the View Slots tab
available near the bottom left of the editor to display the local
coordinates of all slots in the site. You cannot edit slots or templates
with the View Slots toggle set, you must toggle back to the Geometry
tab. The View Slots tab does enable a group of single slot templates to
be rotated by a given angle about a rotation point. This would be used
where a rectangular or circular template had not been used to define slot
spacings but the slots needed to be rotated.

Note:

If curved conductors are defined in Well Setup, then you

will see additional blue slots in the View to indicate
different location of Well Reference Point relative to Slot
(red).

Rectangular Template

Start Number
Start numbering slots from this number. For example, if your site has
two templates each with 9 slots, you may want to start numbering the
first template from 1 and the second from 10.

Numbering
Slot numbers can be ordered by row or column as shown below.

The following graphic depicts Rectangular Template Slot Numbering:

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Slot Geometry
Rectangular templates are defined with a number of spaced rows and
columns with their own regular spacings.

The top left slot is used to determine the location of the Template
Centre. The location of the top left slot is entered as X & Y offsets from
the template centre without considering rotation.

The following graphic depicts Rectangular Template Geometry:

2m
2m
Template
Centre

In the above example there are 3 rows and 5 columns. The template short
name is ‘R’. The row spacing is 2m and the column spacing 2m. The Y
distance to the top left slot is 2m and the X distance is -4m. With the
rotation angle set to 45 degrees our final template appears as above.

Circular Template

Start number
Start numbering slots from this number. For example, if your site has
two templates each of 16 slots, you may want to start numbering the
template from 1 and the second from 17.

With Numbering Clockwise

Slot numbers can be ordered clockwise or counter-clockwise.

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Radius to first slot

Enter the radius of the circular template

Number of slots
Enter the number of slots on the template. These are evenly distributed
about the circle starting at the angle to the first slot.

Angle to first slot

The direction from local north to the first slot.

The following graphic depicts Circular Template Geometry:

This template example has 8 slots. The template short name is C. The
start number is 1, numbered clockwise. The radius is 4m and the angle
to the first slot is 22.5 degrees.

Site Datum Table Editor

All outputs in COMPASS can be referenced to any datum regardless of
the datum to which it was entered or calculated. This is a powerful
integration feature because different engineers or geoscientists in an
organisation can use different datums when referring to the same survey
or plan data.

For example, Geoscientists might use targets and wellpath trajectories

referenced to Mean Sea level (MSL), the Drilling Engineer would

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normally refer to their drilling datum – rotary kelly bushing (RKB) for
rotary drives, drill floor (DF) for top drives. Production engineer’s
reference is from where their production string has been set. In that case,
their datum could be top casing head housing (CHH) or top bottom
flange (TBF). On Land Rigs it is common to have an additional datum
for Ground Level (GL).

The following graphic depicts different datums used at the rigsite:

Kelly Bushing (KB)

Casing Head Housing

(CHH)
Ground level
(GL)

Permanent Vertical System Datum for Field.

For example Mean Sea Level or Lowest
Astronomical Tide

Field Setup is used to define the System Datum and the Site Datum
Table editor is used to define multiple datums for the site. The following
graphic depicts the Site Datum editor:

Negative datum height Two rig datums referenced Date defines when Default datum applied to
for subsea datum within the same Site datum became active all new wellpaths

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To enter a new reference datum:

1 Move to the first free row in the spreadsheet.

2 Enter the name and height from field datum (+ above FD, - below
FD). If available, enter the name of the rig to which it refers. Set the
date after which it is active.

To delete a datum:

1 Click the row number you want to delete.

2 Press DELETE on the keyboard.

Note:

You cannot delete a datum which is referenced by any

wellpath.

Targets
In COMPASS, a target is a sub-surface location (TVD, N, E) with an
assigned geometry and orientation which may be used for planning or
wellpath monitoring. COMPASS enables you to define and assign
geologic and/or drilling targets at the Site level which may be selected
by any number of Wellpaths within the Site.

Once created, Targets can be used by the Survey and Planning modules
and can appear on most of the available graphics and be referenced in
planning and survey reports.

Target Geometry
Each target can have a shape defined about its location. A target can be
geometric, either a Point, Rectangle, Circle or Ellipse or
non-geometric defined as a Polygon with any number of points.

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The following graphic depicts Geometric and Polygonal Targets:

Point Circle Ellipse Rectangle

Polygonal Targets

Each target has an aiming point, the location where the Plan Editor
methods aim to. For geometric targets the aiming point defaults to the
geometric centre. However, this aiming point can be offset laterally and
vertically from the geometric centre using X & Y offsets and thickness
up and down. Thickness enables a planar depth to be assigned to the
geometrical target. Polygonal targets can have variable thicknesses
defined which enables wedge or drillers cones to be modelled. All
targets can be rotated about the aiming point and inclined from the
horizontal along any azimuth, this enables a target to model geologic dip
and strike.

Oriented wedge target

defined using Polygonal
Target Shape

Target Inclined from

Horizontal =
Geologic Dip

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Target Editor
You can launch the target editor from the Edit menu, by selecting Edit,
Site, then Targets or by selecting Edit, Wellpath, then Targets. The
Target list contents may vary, depending on where you launched the
Target Editor. Additionally the Target editor may be fired up from the
Browser by selecting a Site or Wellpath and then double-clicking on the
Targets entry in the lower data display area or right clicking and
selecting Targets... from the menu.

The Target Editor consists of two lists:

• Site targets

• Wellpath target

The Site list contains all targets in the site. The wellpath list is a subset
of the site list that contains targets selected by the current wellpath. Site
and Wellpath icons in the editor toolbar enable you to see both lists.

The Target Editor consists of two panes within a single window, the
Target Editor and the Target View. Like the Template View, the Target
View enables single targets to be viewed graphically in 3D, Plan View,
or Vertical Section. The View is also used to manually define polygonal
targets. It comes with the usual set of online graphical tools.

The Editor area consists of a Target List and underlying Target

Properties area where a target’s name, location and geometry is entered.
Additionally, a drillers target can be constructed using the entered target
TVD and geometry and the positional uncertainty surface of the active
wellpath.

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The following graphic depicts the Target Viewer and Editor windows:

Target List enables all Wellpaths

to select targets within the Site
by clicking on check box

Target Viewer used to

display target geometry
and parameters

Target Properties enables

location, shape, size orientation,
to be defined. A Drillers target
may be defined from shape and
size using planned Wellpath
Positional Uncertainty

Toolbar used to create new, save, update and delete targets. Can display Site or Wellpath
list of targets. Can see 3D Plan or Vertical Section view of target selected in List.

A target should be given a name and useful description. A TVD for the
target is entered relative to a particular depth datum. The target location
can be entered as:

Location Definition

Local Northings and Eastings from Site Centre

Map Northings and Eastings referenced to

Geodetic System e.g. UTMs

Geographic Latitude and Longitude

Polar Distance and Bearing from Site Centre

Lease Line Distances from E/W N/S lease lines

You can define the target location using any of the available methods
and COMPASS will automatically calculate the other entry method
equivalent values using the Field’s assigned geodetic system.

The following is an example of the Target location data entry tab:

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Targets may be locked to prevent

them from being changed by
another user

Target TVD may be entered relative

to any available Site datum

Target location may be defined

using any method. Equivalent
values for the other location
methods are automatically
calculated

Target Shape
A target can be a simple point location, a radius about an aiming point,
a box or rectangular to define lateral tolerance, an ellipse or a
complicated polygonal target with any kind of irregular geometry.

The Geometry tab in the Target editor is used to define the shape for the
currently selected or new target. Within the tab toggles enable the shape
type to be chosen which drives which data entry area will be displayed
in the tab.

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Circular Targets
The following graphic depicts the Circular Target Editor window:

oggles used to select target

hape

Parameter fields enables 3D

target geometry and orientation
to be defined

Start and End Angles

enables ‘pie-shapes’ to be
defined for circular and
elliptical targets

This window enables you to enter a circular target or, by giving the
circle height and a dip angle, you can define a cylinder.

Radius
Enter the radius of the circular target.

Offset of Circle Centre from Target Centre

You can offset the geometric centre of the target from the plan-to point
(defined on the previous window) by entering X (local east) and Y (local
north) offset.

Start and End Arc Angles

You use these angles to define semi-circular or pie-shaped targets.
Leave these angles as zero to keep a full circle. Enter the start azimuth
of the arc then the end azimuth and the arc is completed from the start to
end through the centre.

Thickness
Type a value in the Up and Down fields to change a circular target to a
cylindrical target. The top of the target is Up, the distance above the
plan-to point. The bottom of the target is Down, the distance below the
plan-to point.

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Dip Angle From Horizontal

The dip angle you want to be on at the target. This is 90° minus the
inclination of the target.

Azimuth of Down Dip Direction

The azimuth (direction from local north) you want to be on at the target.

Elliptical Targets
The following graphic depicts the Elliptical Target Editor window:

Rotation angle enables target to be

turned relative to Site North. Target
rotation is about the aiming point.

Thickness Up and Down enables

the aiming point to be offset
vertically within the target.

Formation Plane parameters

enables geologic dip and down dip
direction to be specified, for
example to model a bedding plane.
This may be different to target
rotation.

Semi-minor
Enter the dimension of the ellipse along the local north/south axis.

Semi-major
Enter the dimension of the ellipse along the local east/west axis.

Offset of Ellipse Centre from Target Centre

You can offset the geometric centre of the target from the plan-to point
(defined on the previous window) by entering X (local east) and Y (local
north) offset.

Rotation of the Ellipse about the Target Centre

Enter the orientation of the ellipse from local north. The orientation is
zero when aligned to local north and increases clockwise.

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Start and End Arc Angles

These angles are for defining semi-elliptical or pie-shaped targets.
Leave these angles as zero to keep the full ellipse. Enter the start azimuth
of the arc then the end azimuth and the arc is completed from the start to
end through the centre.

Thickness
Type a value in the Up and Down fields to change an elliptical target to
an elliptical cylinder. The top of the target is Up, the distance above the
plan-to point. The bottom of the target is Down, the distance below the
plan-to point.

Dip Angle From Horizontal

The dip angle you want to be on at the target. This is 90° minus the
inclination of the target.

Azimuth of Down Dip Direction

The azimuth (direction from local north) of the down dip direction. This
is the direction a ball would roll if placed in the formation bedding
plane. Note: This is not the orientation of the target shape.

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Rectangular Target
The following graphic depicts the Rectangular Target Editor window:

30 ft thick target has aiming

point 5 ft below top of target

To Land wellpath in this target,

well inclination would have to
be 75 deg and azimuth of
196.74

Length (Y) and Width (X)

These parameters define the size of the target. Length is parallel to the
local N/S providing no orientation is applied.

Offset of rectangle centre from target centre

You can offset the geometric centre of the target from the plan-to point
(defined on the previous window) by entering X (local east) and Y (local
north) offset.

Rotation of the rectangle about the target centre

Enter the orientation of the target from local north. The orientation is
zero when aligned to local north and increases clockwise.

Thickness
Type a value in the Up and Down fields to change a rectangular target
to a cuboid. The top of the target is Up, the distance above the plan-to

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point. The bottom of the target is Down, the distance below the plan-to
point.

Note:

Target up and down thicknesses are used to define

equivalent formation thickness. This method is useful
because you can define the aiming point at a given depth
below the formation top. For example, if you have a
dipping formation that is 30m thick but want to drill
downdip 5m below the formation top, you define the
aiming point as 5m up, 25m down. This method is
applicable to all target geometries.

Dip Angle From Horizontal

The dip angle you want to be on at the target. This is 90° minus the
inclination of the target.

Polygonal Targets
The following graphic depicts the Polygonal Target Editor:

Each point on a polygon may

be given its own name or
label

Wedge targets may be defined

by changing thickness Up and
Down for each polygon point

Lock Map Co-ordinates

forces the Map E and N to be
fixed so that the local X & Y
coordinates are re-calculated
whenever the target aiming
point is moved.

Note that a polygon can have any number of points defined on it using
the points grid (above). There are three methods available to define
points on a polygon:

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X and Y
Enter local X and Y coordinates from the target aiming point to
define a polygon shape. By default, the last point is joined to the
first to close the polygon. The Y dimension is parallel to the local
N/S providing no orientation is applied.

Map E and Map N

Alternatively enter the map coordinates of the target as given by
the geologists. The Local X and Y are computed based on the
target centre. Note that if the target centre is moved, these
periphery points move as well.

Well Viewer – Define Polygonal Targets

With the target created, press the Define Polygonal Targets icon
. The viewer displays a plan view of the target on which you
can use the mouse to click each point on the polygon. Depress
the icon after all points are clicked and the target editor will join
up the first and last points.

Thickness
Type a value in the Up and Down fields for the polygon depth. The top
of the target is Up, the distance above the plan-to point. The bottom of
the target is Down, the distance below the plan-to point.

Rotation of the polygon about the target centre

Enter the orientation of the target from local north. The orientation is
zero when aligned to local north and increases clockwise. If you define
a Dip Angle (see below) this is the down dip direction of the equivalent
formation.

Formation Plane
You can tilt the formation from horizontal to follow a formation bedding
plane. You can use planning calculations to land the wellpath in the
formation plane at this vector. See Landing Calculator in Planning.

Dip Angle From Horizontal

The formation dip angle that you tilt the target from the horizontal plane.

Azimuth of Down Dip Direction

The azimuth (direction from local north) of the down dip direction. This
is the direction a ball would roll if placed in the formation bedding
plane. Note: This is not the orientation of the target shape.

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Target Selection
The target Sharing and Allocation tools are no longer a part of
COMPASS. Instead target use has been simplified by enabling any
wellpath to select a target for use within a site by simply clicking on a
selection tick box located within the list. Therefore there may be more
than one wellpath referencing a site level target.

The following graphic displays the Target List within the Target Editor:

Targets can be selected by

clicking on the list box

Target Name and Shape is displayed in the list Target location is given in terms of TVD and local
Northing and Eastings from Site Centre

The Target Editor contains two lists, site targets and wellpath targets.
The site list contains all targets in the current site. The wellpath list is a
subset of the site list and contains targets selected by the active wellpath.
To see all the targets in the site click the Site icon in the toolbar:

To see all the targets associated with a particular wellpath click the
Wellpath icon in the toolbar:

Note: neither of these icons are available if a wellpath is not open.

Allocating Targets to Wellpaths

The Target List contains a tick box (see T3 & T4 in list above) that
indicates which targets have been selected by the active wellpath. You
may allocate or de-allocate targets to wellpaths by ticking the box in the
site list.

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Note:

When you add targets with the Site toolbar icon

depressed, you must specifically allocate the target to a
wellpath in order for it to be used. When you add targets
with the Wellpath toolbar icon set, targets are
automatically allocated to the current wellpath.

Drillers Targets
Click on the Drilling Target tab to create a new target that is reduced in
size from the original by survey error at the TVD depth of the target. The
drilling target is a zone drawn within the geological target, that when
drilled within and monitored using survey instruments with
inaccuracies, will stand a good chance of hitting the geological target
boundary. This drilling target tool can be used to design a cost effective
survey program so that the wellpath meets it geological objectives.

About Drilling Targets

A Drilling Target is an area in a geological target boundary that is
intersected to ensure that despite the positional uncertainty caused by
survey tool errors, the well intersects the geological target.

If a geologist assigns a target with X dimensions and you drill to it using

MWD you may hit it near the edge. When the path is resurveyed using
a Gyro, quite often the wellpath ends up outside the target. To prevent
this, planners should reduce the geologist’s target by the expected
survey error radius, which is determined by drilling with MWD
(possibly tied to a gyro at the previous casing). Create a definitive path
from the principal plan with the survey tools defined on the plan for the
situation when drilling the final section of the hole to the target (that is,
Gyro in intermediate Casing and MWD in open hole).

Drillers Target Algorithm

The following explanation describes the statistical algorithms employed
to construct a driller’s target from a geological target using the
positional uncertainty surface calculated for the wellpath down to the
TVD of the target.

Surveys show that a wellpath has penetrated a target at position

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Uncertainty at this position is represented by an error ellipse (this one

drawn at 2 standard deviations).

Points are 100 possible repeat survey locations of the actual point of
Geological
Target

penetration in the target. The 8 points lying outside the target represent
the 8% probability that the target has been missed. From this, the
inclusion probability of hitting the geological target at the calculated
point is 92%.

We can calculate the inclusion probability at every point within the

geological target and colour code it as follows:

< 90%

90-95%

> 95%

Drillers Target
defined from 90%
confidence contour

Well
Direction

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The following graphic depicts the Plan View and 3D view (inset)
displaying a reduced size Driller’s target constructed from a circular
Geologic Target using the displayed Error Ellipse dimensions down an
example wellpath. The drillers target was constructed using a 75%
confidence level:

Geological Target

Drillers Target

Select the confidence for hitting the target. The confidence is the
percentage probability that if the wellpath, when surveyed, intercepts
the target at this point, that it really is within the boundaries of the target.
A useful range is from 80% to 95%. Neither 0% nor 100% is possible.
The drilling target boundary represents a contour of confidence, points
within the boundary represent better than the required confidence.

Because the Driller’s Target tool uses the errors on the current definitive
path at the depth of the target, if the path does not go to this depth or no
errors exist, an error message appears. Additionally to construct a
driller’s target, the tool needs a geological target that is big enough to fit
the errors otherwise an error message appears saying the target isn’t big
enough. In this situation, you have two options, use a bigger geological
target, or assume a more accurate survey program (& possibly more
expensive!) to make the errors smaller. The driller’s target is given the
name of the original target with the confidence label displayed.

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Note:

In the live views, it is possible to only display drillers

targets and hide geological targets. Look in the Options
tab in Graph Setup.

Target Viewer
The target view displays the currently selected target, which you can
toggle as a Section, Plan, or 3D view with the usual 3D tools available.
You can use the Target viewer to define polygonal targets and to change
the landing point for directional well planning calculations.

Target Landing Point Adjust

When planning or doing project ahead, the target viewer has another

use. If a target is selected from a drop-down list, click to

adjust the landing point. This invokes the target view in adjust mode.
Click anywhere on the section or plan view to adjust the landing point.
The plan or projection immediately updates it’s calculations using this
new point. Note that this does not change the target location.

To change the landing point for planning calculations:

The landing point or aiming point is defined in the Target Editor.

1 Create a new plan or open an existing plan.

2 Select a planning method that lets you select a target. For example a
2D Slant well.
3 In the Plan Editor select a target.
4 Click Adjust.
5 In the Target View window, move the cursor to the coordinates to
which you wish to aim and click the left mouse button.
The plan is automatically be re-calculated to hit that point.
• To change the horizontal location click the plan view icon .
• To change the vertical location click the section view icon .
• You can also type in the landing point coordinates and click Set.

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• To revert to the original coordinates click Reset.

Wellpath Editors
In addition to the Survey and Plan editors, other data is linked to the
wellpath that you can define using dedicated editors. This information
consists of the Definitive Path, Targets, Casings, Formations, and
Annotations. All of this data can appear in Reports, online Graphs, and
Wallplots.

The following graphic depicts a 3D View of available Wellpath Data:

Wellpath Data can be displayed in Reports and
any kind of live graph or wallplot

Casing Information - Shoe & Names

Annotations

Formation/Stratigraphic Information

Target Names & Geometry

Error Ellipse - Calculated Positional Uncertainty

Survey Program Editor

Definitive Survey
Wellpath position is determined by processing the results of one or more
directional surveys and calculating their combined wellpath trajectory.
As drilling proceeds, surveys are taken of the new hole section and
sections of wellpath can be re-surveyed using more accurate survey
tools. At different times during planning or construction of the well,
different combinations of plans and surveys are used to calculate what
is commonly called the ‘Definitive Survey’ which defines the complete

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wellpath trajectory. Some companies refer to a ‘Running Definitive

Survey’ while planning/drilling a well and the ‘Final Definitive Survey’
when the well is completed and the final surveys QA’s and tied together.

The following table depicts a simple Survey Program consisting of 4

Parts:

Survey Program Program Part 2 Program Part 3 Program Part 4

Part 1

36” hole s/shots 36” hole s/

shots

30” csg m/shot 30” csg m/shot

26” hole s/shots 26” hole s/shots

17-1/2” hole s/shots 17-1/2” hole s/

shots

13-3/8” csg m/shot 13-3/8” m/shot 13-3/8” m/shot

12-1/4” hole s/shots 12-1/4” hole s/

shots

12-1/4” hole m/shot 12-1/4” hole m/

shot

8-1/2” hole m/shot 8-1/2” hole m/shot

In the example above, Program Part 4 would comprise the final

Definitive Survey comprised of 3 surveys. The wellpath would still
contain the 4 other surveys, but they are not in the Definitive Survey.

Editor
The Survey Program Editor enables you to select the surveys or plan
combinations to compute the Definitive Wellpath for either a planned or
actual trajectory. The Survey Program editor maintains a record of the
definitive path’s current and previous compositions and enables you to
add new surveys or make modifications to use more accurate surveys
within particular depth ranges. The tool also enables the final Drillers
Depth to be recorded so that it is included in the trajectory.

The survey program dialogue operates in 2 modes:

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• The traditional Survey History mechanism seen in earlier Compass

versions (1998.2 and earlier). This is the default for the Planning
Mode check box. Survey stations for the definitive path will be
assembled using the depths defined in the program.
• The Survey Program mechanism. This is the default when the
company’s anti-collision method is Travelling Cylinders and
Planning Mode check box will be ticked. It will use the planned
survey depths to determine the order of surveys, but will use the
actual survey depths for splicing together the definitive path. A
station is added at the end for the projected depth.
The following graphic depicts the Survey Program Editor in History
mode:
Flag for Locking Version Info for information Projected Depth to Toggle between History (off) &
Wellpath only, has no other effect appear in reports Planning modes (on)

Edit the current

survey program Click in this column and select the
plan/survey from the drop down list

View previous Survey

Programs by Date

Whenever the survey program is updated, COMPASS records the date

and the names of the surveys used to compile the Definitive Wellpath.

Survey Program lets you Edit the sequence for today and View the
record for previous Program Dates. This enables you to view, but not
edit, the status of the Definitive Wellpath for previous days. You can
delete historical survey histories if you want to remove them from the
COMPASS database.

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The following graphic depicts the Survey Program Editor in Planning

Mode:
Survey Program Editor in
Planning Mode

Surveys entered in the sequence that they View the planned sequence of survey
will be run, all referenced against the Program Parts while drilling the well
Planned Trajectory

Survey Program Grid

Depth From
The measured depth of the first measured station in the survey.

Depth To
The last measured depth in this survey section. When the survey is
selected the depth from and depth to are populated based on the
information in the survey.

Survey/Plan (Wellpath)
Select the survey to use for this section of the wellbore. For sidetracks
this can be taken from the original hole. You also use this field to place
the principal plan in the Definitive Wellpath, but this must be the last
part of the history as subsequent sections are ignored.

Tool
Tool selections are automatically taken from those assigned to the Plan
or Survey, and are used to calculate positional uncertainty. However, if
not using Planning Mode you may change the tool allocation within
Survey Program editor so the positional uncertainty of the wellpath is
calculated using a different survey tool error model.

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Do Not Use (Planning Mode Only)

Indicate that this survey has been planned or run but will not form any
part of a definitive path.

Use In Preference (Planning Mode Only)

Use this survey in preference to later surveys. Normally later survey
depths in the program would supersede previous survey depths, but
should a high accuracy survey be planned with subsequent overlapping
lower accuracy surveys, part of the lower accuracy survey will be
overwritten.

The following 3 selections apply to the definitive path in general:

Selection Description

Validated Definitive Survey You can set this Program and Definitive
Wellpath as the validated version and lock the
wellpath against further edits. You should set
the wellpath to Validated once survey
operations on the well are complete and
reviewed.

Version Number You can assign a version number to the

history and definitive path. This entry appears
in reports in the survey history section.

Projected Depth You can enter the final Drillers Depth here.
This depth is not included on any surveys, but
is reported as PROJECTED TD at the end of
the definitive path survey report.

Program Management
The default mode of the program editor is to create a new sequence,
which will then supersede previous records, which are not lost but
remain as past records of the program.

• Latest Program - Edit the current program through the grid.

• Program Date - Examine the states of previous programs. Change
to mode of the program editor to view previous states of the
program by date. Previous states of the program may not be edited.
• Program Parts – Examine the state of the program when each of
the chosen surveys is run. This will show both the tie-on sequence
for the surveys, but also the survey instrument sequence when new
sections of hole are drilled.

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Program Date
Enter the date when the program was constructed.

Delete Program
Clicking this button will delete the currently selected program by date.

History Mode:
• You can append to the end of the Definitive Wellpath whenever you
save a plan or survey when the survey program is not in planning
mode.
• A plan name can be included in the Definitive Wellpath if the
wellpath has a Principle Plan and is selected to form part of the
trajectory.
• You can add one plan to the Definitive Wellpath. Because surveys
are real and plans imaginary, when you add a plan to the Definitive
Wellpath you cannot add a survey after a plan.
• Tool histories and Definitive Wellpaths are not regenerated
automatically. To regenerate a Definitive Wellpath you must select
add to history when saving a plan or edit the survey history. You
can use the survey program to quickly regenerate a Definitive
Wellpath as surveys change on the wellpath.
• On sidetracks, the history also shows surveys on the parent
wellpath. You should not edit these.
• When you select a survey in the program editor, click the depths
columns to view/change depths.
• Surveys are re-computed from the start of the 2nd survey in the
Definitive Wellpath, therefore inertial surveys must be the first
survey.
• The 'use in preference' and 'do not use' columns are not available.
In addition to how the Survey Program is handled within the editor,
when handling surveys if Planning Mode is not ticked, then the
following will occur:

• You will be prompted to ‘Add Survey to Definitive Path?’ when

you save a survey/principal plan.

• The Survey editor will support use of an interpolated tie-on point

in the definitive survey, if you have tied a survey as such.

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So its best not to turn it on unless you know what you are doing. It will
almost always default to off, unless the Company Setup has a specific
configuration.

Planning Mode
• The survey program should be used when the well is being planned.
Mark out the surveys that you plan to run by entering the Depth
from & to and the type of instrument. Leave the survey column as
‘Planned Survey’.
• You enter the surveys in the sequence that they will be run (or
processed), note that later surveys take precedence over earlier
surveys in the definitive path
• If sidetracking from an existing well, then the program will ‘copy
over’ the surveys from the parent wellpath. Do not change these
unless you are planning to re-survey part of the original hole.
• When real surveys are run, then supersede the ‘Planned Survey’ in
the program with the reference to the real survey. An error will be
indicated if the real survey does not have the same ‘Tool Type’ as
the program.
• Some surveys may be marked in the program as ‘Do not use’; this
indicates that the survey is planned but will not form part of a
definitive path.
• Some surveys may be marked ‘Use in pref.’; this indicates that
should the survey depths overlap later surveys, then this marked
survey will supersede the later survey depths.

Wellpath Casing Editor

The Casing editor is used to define casing shoe depths and sizes down
the wellpath. This information may then be used for plotting, reporting
as and may be configured for use in an anti-collision scan. You can
launch the editor from the toolbar, browser, or by clicking Edit,
Wellpath, then Casing from the main menu.

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The following graphic depicts the Wellpath Casing Editor:

Enter Shoe MD or TVD, Compass

will interpolate the other value
using the Definitive Wellpath Diameters may be
Trajectory included in anti-collision
scan

Casing names may be

types or selected from a
picklist

Casing dimensions (Casing Size & Hole Size) will be added to error
dimensions for anticollision scans, when configured in the Company
Setup. Hole Size is hole diameter that the casing was run into, it is used
only as the diameter of the reference well in anticollision; the casing
sizes are used for all offset wells.

To add a casing point:

1 Enter the name of the casing, or select one from the drop-down list.
This is the name that appears on graphs and reports.
2 Enter either the MD or the TVD of your casing point. COMPASS
interpolates the other.
3 Enter the Diam (diameter) of the casing or select one from the drop-
down list. Casing dimensions can be considered during an Anti-
collision scan if the error surface is set to include Casing. For more
information, see Company Setup window.
4 Click OK to save the entered casings.
5 A popup window appears asking you to save Casings to the
Definitive Path. If you want to include Casings for Anti-Collision
purposes or plot Casing tunnels in the
Anti-Collision plots, click Yes; otherwise click No.

Vertical Depth Reference

Select a datum for referencing the casing depths. You should do this if
the well is pre-planning before a rig has been selected, or if the casings
are to be set at a hydrostatic depth below a system datum (MSL).

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Setting the Default Picklist for Casing Names and Diameters

The Casing List Editor is accessed from the Utilities menu. Use the
Casing List Editor to configure standard casing names and sizes that can
then be picked in the Casing Editor for plots and reports. The casing list
is stored in the local registry.

The following graphic depicts the Casing List Editor utility:

Casing Names are labels that appear

in plots and reports

Casing Sizes are equivalent diameters

which may be included in an anti-
collision separation factor calculations
to model metal-metal (edge-edge)
separation as opposed to centre-centre
separation

Be sure to define these correctly!

To add a casing point to the list:

1 Enter a unique casing name in the left column of the grid.

2 Enter a casing and hole size in inches to use for anticollision when
required.
3 Repeat steps 1 and 2 until the required casings set is complete.
4 Click OK to save the casing list.

Wellpath Formation Editor

You can launch the Wellpath Formation Editor from the toolbar,
browser, or from the Edit-Wellpath-Formations menu item. The grid
enables Formation or Stratigraphic tops to be entered that could be used
to create geological targets.

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The following graphic depicts the Wellpath Formation Editor:

Depths can be viewed/

referenced relative to any
datum

Grid enables multiple

Stratigraphic Tops/Boundaries
to be described. This includes:

• MD along wellpath
• TVD below Wellhead
• TVD on wellpath
• Formation Name
• Lithology
• Dip Angle
• Dip Azimuth

Target can be created from Formation Top

information

To add a Formation Top:

1 Enter a name for the Formation. This name appears on graphs and
reports.
2 Enter either the MD or the TVD Wh of the formation top.
COMPASS interpolates the other.
3 Click the Lithology field then select a lithology from the drop-
down list. Lithologies are associated with bitmaps which enables
Geological Columns to be included in Wallplots. You can modify
custom lithologies using the Lithology Editor (see below).
4 Enter the Dip Ang. and Dip Dir. These values are used to draw
formations layers on plots.

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To create a Target from a Formation Plane:

1 Highlight a formation line by picking the box to the left of the

formation.
2 Click Make Target button. The target will be created and you will
be advised of its name. It will automatically be selected by the
current wellpath.
3 When generating a target from a formation in the formation editor,
the formation Dip Dir translates as Target Orientation not Azimuth
of Downdip Direction.

A target is constructed with the formation plane, name, and wellpath

identifiers. You can now use this target in planning.

Dipping Formation Model Definitions

Some definitions are required to understand the dipping formation
model.

MD
When the measured depth of the formation is on the wellpath this is
entered while or after the well has been drilled. The MD pick comes
from cuttings, and logs run while or after drilling.

TVD Wh
When the TVD of the formation is directly below the wellhead or
vertical section origin this depth is entered during planning. If TVD is
entered then MD changes on the wellpath.

TVD Path
This is the vertical depth at which the formation intercepts the wellpath.
This field is output only and is the same as TVD Wh if the formation is
horizontal (no dip).

Lithology
This name is picked from a list of lithologies and is used to plot the
formation column.

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Dip Angle
This is the maximum angle from horizontal of the formation (down dip).
The dip angle can change if MD is entered, and is computed based on
the wellpath interpolation and the TVD below wellhead.

Dip Direction
This is the azimuth of the down dip angle.

Formation steering
A number of features are in COMPASS for formation steering.

Formation Editor
The Formation Top Editor interpolates dipping formations on the
current wellpath. Enter TVD Wh, which is the top vertical depth below
wellhead or section origin. It has an extra column for TVD Path that
shows the TVD on the wellpath. Enter MD on the wellpath for the top
and COMPASS computes the dip.

Make Target
Create a target for planning from a formation top. This creates or
updates a planning target based on the formation top. This target can be
used in projections and landing calculations. In the planning module,
there is also a projection to target plane method.

Formation Lines on graphs

Include formations on the section graph shows lines from the section
origin down the dip where the formation plane intercepts the vertical
section plane. It also labels the points on the wellpath at the intercept
with the formation plane.

Project ahead to back-on track to formation

You can select the formation top and it calculates as follows:

• Calculates vector in formation plane to land in, use the current

wellpath azimuth all the way.
• Calculates the minimum curve-hold-curve (or hold curve) to get
into the formation by the given measured depth and at the stated
dogleg severity. If the given MD is not possible, COMPASS
calculates the minimum depth to do this in 3m or 10’ increments
from the stated depth. To land a specified depth (X m) in the

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formation, enter an artificial formation top as the level into which

you want to get (i.e. Top reservoir + X).

Wellpath Annotation Editor

You can launch the Wellpath Annotation Editor from the toolbar,
browser, or by clicking Edit, Wellpath, then Annotations. The
Wellpath Annotation Editor is a simple spreadsheet that enables you to
place additional labels on a wellpath referenced to a MD or TVD. Free
text enables you to highlight points on the plan or wellpath such as
overpressured zones or stuck points. The editor behaves in the same way
as the Casing and Formation editors, in that if you enter a MD or TVD
COMPASS will interpolate the other value.

Lithology Editor
You access the Lithology Editor from the Utilities menu to configure
bitmaps to lithology names that can then be used in formation columns
for section views in all parts of COMPASS.

The following graphic depicts the Lithology Editor utility:

Lithology Names may be customised for

particular operating areas. Simply type in the
name into the grid cell.

Bitmaps refer to.BMP files that must be located

in the COMPASS\CONFIG directory for them to
be recognised. Use the drop down picklist to
select.

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To define a Lithology:

1 Enter a unique name in the left column grid.

2 Select a texture file from the list of BMP files stored in the
COMPASS\config directory.
You can preview the selected texture in the area below the grid.
3 Repeat steps 1 and 2 until the required set is complete.
Click Ok to save the lithology.

Graphics
There are two types of graphics in Compass:

Graphic Description

Live graphs or views Primarily designed for onscreen viewing but

can also be output to a printer or exported to
file

Wall plots Designed for printer or plotter output that can

be scaled, text edited, and moved.
Wall plots are covered in a separate section in
this manual.

You can use live graphs at any time to view your work. These graphs are
termed live because they are online and are updated automatically as
data is changed in the editors or data entry windows.

Examples of live graphs are:

• 3D view
• Vertical Section view
• Plan view
• Target Viewer
• Template Viewer
• Site Optimiser Viewer
• Wellpath Optimiser view
• Anti-Collision Plots

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For presentation output, use Wallplots in COMPASS because online

graphs are not WYSIWYG (What You See is What You Get). All live
graphs are formatted as they are sent to the printer. You cannot access
formatting like in Wallplots where you can format everything. You can
only change graphic features such as scale and print area.

You can print a live graph using the toolbar icon. However, a better
method is to use the Print Preview feature by clicking File, then Print
Preview. The Print Preview window displays the formatted changes and
uses the actual printer driver to present the graph on the window. This
enables you to see exactly what will be printed before you send it to
hardcopy.

The Live views can display different types of Wellpath data. In addition
to the Definitive Path (default colour = Blue), live graphs display:

• currently open Survey (default colour = Red)

• currently open Plan (default colours = Red and Green)
• Survey Project Ahead sections (default colour = Green)
• Other wellpaths in the Field using Offset Wells

Customising Live Graphs

Graph Setup

You can launch the General Graph Setup window from the toolbar or by
clicking Utilities then Graph Setup. Graph setup enables you to
configure the general appearance of the live graphs.

Colours and Symbols

To help distinguish different trajectories on a graph, you can assign
different colours and symbols to:

• Definitive Wellpath
• Current Survey
• Current Plan
and only colours to:

• Targets
In the options for the Offset Track Colours you can choose:

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• Multi-colour to assign a different colour to each new track.

• Colour by Type to assign pen colour based on the type defined in
the Wellpath set-up. The colours are assigned to Wellpath types in
the Wellpath Type Editor
• Colour to assign a constant pen colour to all offset wells

Font Sizes
When you enlarge graph details using zoom some text is enlarged while
other text is unchanged.

The reason for this is that enlarging titles and axis labels gives a clear
indication that the view is magnified. However, when you zoom in to
magnify detail, you don't want to make symbols, depth labels, and
casing shoes, too large to read.

Sizes (% of the Window)

Text in this category does not change size as you enlarge the view. Font
sizes are shown as a proportion of the window size, so when you change
the window size, the font size also changes.

Sizes (% of the Graph)

Text in this category changes size as you enlarge the view. Font sizes are
shown as a proportion of the graph size. When you change the window
size, the font size does not change. Also when there are multiple graphs
on a plot, such as an analysis, plot symbols and data labels are scaled to
the area occupied by each individual graph not the overall windows size.

Spacing between symbols

The frequency with which symbols are plotted along a wellpath.

Black Background
This switches the graphs to display on a black background. Black lines
now appear as white lines.

Graph Toolbar Icons

Live graphs can be launched from the View menu, the main toolbar, or
automatically when certain tools are opened such as Target and
Template viewers. Each graph has its own set of properties and tools,
but there is a common subset of tools.

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The following graphic depicts the COMPASS Live Graphs Toolbar

Icons:

COMPASS for Windows Live View Icon Map

Online Help

• Fire up the Help to see the tips available for the

current graph
Close
Print Live View
• Turn off the graph
• Format, then send graphic to printer
Graphics Offset Wells
Display Definitive Wellpath
• Select Offset Wellpaths to include
in current plot
• Turn Definitive Wellpath On/Off
Zoom Out
Zoom In
• Click to pan out to original scale
• Click area to zoom in on
Rescale Axis
Line Data Reader
Drag mouse pointer to reduce graph area
• Read X & Y axis values on selected point along line
• Move Mouse to select point
Point Data Reader

• Read X & Y axis values from selected point on graph

• Read Delta X & Y between 2 points on graph

Symbols

• Turn on Line Symbols for B & W

Printing
• Helps differentiate lines on plot
Axis at (0,0) On/Off

• Major grid axis displayed in centre or to left of plot Display Error Surface
Formations
• Display ellipse of uncertainty
along wellpath
• Display Formation Tops
• Ellipse interval may be adjusted
Display Casing Shoes in graphic options
• Display casing shoe symbols and • Ellipse is projected onto viewing
labels along wellpath surface
Grid On/Off
Display Targets
• Turn grid lines on or off
• Include Wellpath targets in plot • Useful to turn off grid lines on b & w plots
Vertical Section Lines
Horizontal Section Lines
• Display Vertical Section Lines in Plan
• Display Horizontal Section Lines in Plan
Data Labels On/Off
Axis Labels On/Off
• Turn display of data labels on or off
Graphics Options • Turn display of axis labels on or off

• Access to all Live View/Wallplot Customisations

or simply double-click on graph

You activate these additional tools and settings by clicking the icon. The
appearance of the graph can change or an additional window can appear.
The most useful feature is the online help available for each type of
graph. Each graph type has its own subset of tools to manipulate the plot,
and graphic options to customise the plot.

There are additional icons that appear on certain graphs.

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Legend Box
When you launch a live graph, COMPASS also opens a Legend Box that
contains a list of all wellpaths displayed on the current view.

To change wellpath colour or symbol, double-

click on it within the Legend and choose from list

The selected wellpath line will be highlighted in

bold on all live views

The Legend Box has the following features to help you distinguish
different wellpaths.

• The first wellpath is always the current Definitive Wellpath.

• If you open a survey or a plan it is next in the list.
• The next line is a blank line.
• The rest of the Legend contains additional offset wellpaths.
• Clicking on a wellpath name in the Legend Box highlights its trace
in the graphic view.
• Clicking on the blank line unhighlights all wellpaths.
• Double-clicking the name of each offset wellpath in the Legend
Box changes its colour or symbol.
• To change the colour of the current wellpath or survey, see Graph
Setup.

3D View
This is one of the most commonly used Live graphs, as it quickly
enables you to obtain a good overall perspective of wellpath trajectory
entered in Compass.

There are two types of tools available:

• Keyboard quick keys

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• Toolbar icons
The following graphic depicts the keyboard quick keys and toolbar
icons:

The 3D view is actually a 2D line drawing representation of 3D. When

zoomed out, perspective is easy; however, when you zoom in and start
rotating objects it becomes difficult to keep your frame of reference. If
this occurs, zoom out, regain your perspective, then rotate the object
back to where you think it should be, and zoom in again.

In addition to the keyboard, you can use the left mouse button to drag
the 3D view around and the right mouse button to zoom in and out.

Vertical Section View

The Vertical Section view displays the current wellpath as projected
onto a vertical plane defined in Wellpath Setup. You can add additional
wellpaths to this plot, show target and casing details, and use the line
data reader to select points on the wellpath.

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Plan View
The plan view displays a horizontal projection of the wellpath. You can
display the current line of the vertical section from the origin to the end
of the wellpath.

Geodetic Calculator
The geodetic calculator is a simple tool used to calculate Grid
Convergence and Scale Factor for a given location assuming a chosen
geodetic system. You can use it to do quick geographic conversions and
calculate a UTM zone from geographic coordinates. Calculated results
are displayed on window and can be shared using Windows Notepad.

The Calculator
The following graphic depicts the Geodetic Calculator:

Full selection of Geodetic Systems and

Datums available. A Geodetic
Coordinate ‘System’ comprises the
Geodetic System itself, a Geodetic
Datum or Ellipsoid and a Map Zone

Location may be entered as local offsets

from Site Centre, Map Coordinates or
Geographic Coordinates

Can determine appropriate UTM zone

from entered Latitude & Longitude

A short Geodesy Report is available using the Windows Notepad

feature. This text can be easily printed or copied to other documents
via the Windows Clipboard

Geodetic System, Datum and Map Zone

You must select the correct geodetic system before doing geodetic
conversions (latitude and longitude <> easting and northing). The
default system is taken from the current Field. If you do not know the
appropriate geodetic system, select Flat Earth.

Some Geodetic Systems have a fixed Datum (e.g. Nigerian Projection

System uses Clarke 1880) while others (e.g. UTM) enable any datum to
be selected. Additionally some Geodetic Systems have a fixed Map

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Zone (e.g. Brunei/Borneo grid = NW Borneo Grid) or enable a selection

of one or more Map Zones (e.g. Lambert Algerie North & South).

Select one of the input coordinate types using the radio button, then
enter the position of interest in the coordinate system based on the
following criteria:

Position Criteria Description

Local to Site Enter the location of interest as local

Northings and Eastings from Site Centre.

Map Position Enter Map coordinates based on the Geodetic

System.

Geographic Geodetic coordinates of your location based

on the Spheroid.

Results

Grid Convergence
The angle difference from True North to Grid North for the location.

Scale Factor
The scale factor is the ratio between measured distance on the map and
measured distance on the ground at the location. Even though it is
calculated, Scale Factor is not used to conduct map to local coordinate
conversions unless the COMPASS geodetic system configuration file is
setup to apply it. Scale Factor conversion is normally turned off by
default.

UTM Zone
The geodetic calculator has a UTM Zone button to compute the correct
UTM Zone for the latitude and longitude you enter. This button is only
available when you choose the Universal Transverse Mercator system.

Geodesy
Geodesy is the science of measuring the earth’s surface. The Earth is
round (sort of) and maps are flat. A geodetic system enables you to
convert geodetic coordinates (angles on a round earth - latitude /
longitude) to map coordinates (distances on a flat map - easting /
northings). To do this you must know the system, the datum (ellipsoid),
and the zone.

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System
A geodetic system is one or more map projections covering adjacent
parts of the globe. A system can comprise one or more zones. If you do
not know the geodetic system for your area or if you have no need to
convert between geodetic and map coordinates select Flat Earth. By
selecting Flat Earth you disable conversion between geodetic and map
coordinates through out the Field. Otherwise, select the geodetic system
agreed for use in an area.

COMPASS ships with a pre-defined set of geodetic systems that cover

the majority of systems used in the oilfield. Certain locations require
additional or customised geodetic systems, these are easily added in
COMPASS as geodetic configuration files which are commonly
constructed by your regional Landmark Support Office.

Datum
A datum or ellipsoid is essentially a mathematical model that best
represents the actual shape of the Earth’s surface in a given area. The
Earth’s surface is generally geometric like an American football or
rugby ball. However, it is an irregular, slightly flattened sphere - a geoid.
We cannot compute geodetic conversion on a geoid so we assume the
earth to be an ellipsoid. Because the earth's surface is irregular, different
shaped ellipsoids better represent different parts of the globe. The size
and shape of the ellipsoid varies depending on part of the globe mapped.

Regional geographic organisations and even oil operator survey

departments recommend which geodetic system and ellipsoid to use for
a given operating area.

Map Zone
A geodetic system can contain one or more map zones. Each zone maps
a different area. Following are three examples of geodetic systems
shipped with COMPASS:

US Stateplane Coordinate System 1983

This system maps the United States. It is a combination of
Transverse Mercator and Lambert Projections and comprises 124
zones. Most States have more than one zone - Alaska has 10 zones,
Texas has 5, Maryland has only one. Unlike the UTM projection,
just one ellipsoid is used for the entire system - GRS 1980.

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Universal Transverse Mercator

The UTM system maps the entire world by dividing it into 60 zones
each 6° of longitude wide extending up to 84° N and S. When the
UTM system is selected COMPASS makes all datums available and
lets you select any one of the 60 zones north or south.

The diagram below depicts a UTM zone covering both southern and
northern hemispheres. Two reference points are plotted, one in the
West side of the Northern Hemisphere, the other in the East side of
the Southern Hemisphere. Note that convergence (angle from True
North to Grid North) for both points is negative. In the other two
quadrants (NE & SW), convergence is positive.

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UK National Grid
This system maps the United Kingdom, has one zone, and is based
on the Airy 1949 ellipsoid.

Geomagnetic Calculator
Where the local magnetic field cannot be measured or obtained, the
Geomagnetic calculator enables the local geomagnetic field to be
calculated using a set of Geographic coordinates, a Date, and a
predictive global Geomagnetic model. It is most commonly used to
calculate magnetic declination that is a required correction for magnetic
survey readings.

The calculated values are not used in any COMPASS calculations.

However, the results appear in most surveying reports and the Site data
block in Wallplot Composer output. A Norths arrow is displayed in the
Status Box reference area which can also be included in a Wallplot.

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The Calculator
The following graphic depicts the Geomagnetic Calculator:

Location defaults from current Site.

Change it by retyping, using up/Down
arrows or selecting Field, Site, Well or User
defined location

You can compare the results from different

Geomag models; however beware of date
restrictions on certain models

Vertical Depth value can be entered to

calculate geomag field lower down the
wellpath

Date defaults to current date, but it can be

changed to compute historical values

A short Geomagnetism Report is available using the Windows

Notepad feature. This text can be easily printed or copied to other
documents via the Windows Clipboard

The Geomagnetic Calculator can be launched from the Site Setup

window or from the COMPASS toolbar. The geographic coordinates
default to those of the current site, assuming that a site is open with a
geodetic system defined. The date defaults to today, but can be changed
to any date. The geomagnetic model defaults to that selected in Site
Setup.

The Geomagnetic Field can be calculated at surface or calculated at

different TVDs below the current site. This is a useful feature to gauge
the effect of TVD on declination of surveys taken down the wellpath.

Results
The Geomagnetic field varies slowly in time and can be described as
that of a bar magnet with north and south poles deep inside the Earth and
magnetic field lines that extend well out in space. Because the field
varies, models are used predict what the geomagnetic field is at a
particular time and place.

The results are in nanoteslas (nT) and degrees (°).

The geomagnetic field can be quantified as total field, dip angle,

horizontal intensity, vertical intensity, and declination. Total field or
total intensity is the magnetic strength, that ranges from about 23
microteslas (equivalent to 23000 nanoteslas or gammas, or 0.23 oersteds
or gauss) around Sao Paulo, Brazil to 67 microteslas near the south

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magnetic pole near Antarctica. The angle of the field relative to the level
ground is the dip angle or inclination that is 90° at the north magnetic
pole. Note dip angle is positive downwards.

Vertical and horizontal intensity are components of the total intensity.

X-North is the component of the magnetic field that is aligned north /
south. Y-East is the component of the magnetic field that is aligned east
/ west. Z-Vertical is the he component of the magnetic field that is
aligned with gravity.

Finally, the angle of the horizontal intensity, with respect to the north
geographic pole, is declination. Declination is the angle between where
a compass needle points and the true north pole.

The following graphic depicts the Seven parameters of the Earth’s

Magnetic Field:

Results can be shared with other colleagues or contractors using the

Notepad feature.

Geomagnetism
What is the Magnetic North Pole? The Earth's core has remained molten
due to heat from ongoing radioactive decay. Convection currents
flowing in the outer core generate a magnetic field, but the poles of this
field do not coincide with north and south poles (the axis of rotation of
the Earth). In early 1998, the average position of the modeled north
magnetic dipole (according to the IGRF-95 geomagnetic model) was
79.5° N, and 106.3° W, 40 kilometres north-west of Ellef Ringnes Island

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in the Canadian Arctic. This position is 1170 kilometres from the true
(geographic) North Pole.

It is generally believed that a compass needle points to the magnetic

north pole. Because the geomagnetic field is the effect of complex
convection currents in magma composing the Earth’s core, the local
field must be described as several dipoles, each with a different intensity
and orientation. Because of this, the compass needle actually points to
the sum of the effects of these dipoles at a given location. In other words,
the needle aligns itself with the magnetic lines of force. Other factors, of
local and solar origin, further complicate the resulting field. It may be
all right to say that a compass needle points to magnetic north but it only
roughly points to the north magnetic dipole.

The following graphic depicts the Magnetic Declination variation as

calculated by IGRF95. Mercator projection. IAGA Division V,
Working Group 8, International Geomagnetic Field, 1995 Revision, J.
Geomag, Geoelectr.,47,1257-1261, 1995:

Geomagnetic Main Field Models

A geomagnetic main field model is a set of a few hundred numbers
determined by 3D curve fitting a large number of geomagnetic field
observations from sites around the world. Predictive geomagnetic

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models can be used worldwide and only predict the values of that
portion of the field originating in the deep outer core.

Different geomagnetic models are available, some of which are used

within Compass:

• World Magnetic Model (WMM) updated every five years. Public

model available from the US Department of Defense who provide
on behalf of the US National Geophysical Data Centre. Available
from the Internet at http://ftp.ngdc.noaa.gov/seg/potfld/
DoDWMM.shtml.
• International Geomagnetic Reference Field (IGRF). Public model
updated every five years. Available from the International
Association of Geomagnetism and Aeronomy on their Internet site
at http://ftp.ngdc.noaa.gov/IAGA/wg8/igrf2000.html.
• Definitive Geomagnetic Reference Field (DGRF) model describes
how the field actually behaved. This is also provided for 5 year
intervals and is also available from the International Association of
Geomagnetism and Aeronomy.
• British Geological Survey Geomagnetic Model (BGGM). The BGS
annually computes a model of the geomagnetic field, meeting the
demands of accuracy and Quality Assurance required for
directional drilling and well placement. The BGGM is supported by
major oil companies, service companies in the oil sector, and by the
Health and Safety Executive.The model is updated every year and
therefore considered more accurate. It is a commercial model and
therefore not shipped automatically with Compass. Clients must
provide proof of a license from the BGS before Landmark will ship
geomagnetic model files for use with BGGM. Information is
available from the BGS on the Internet at http://192.171.143.111/
bggm.html.

Factors that Influence Declination

The following factors influence declination and therefore magnetic
survey instruments. Their effects are noted in brackets:

• Location (one to thousands of kilometres/degree)

• Local magnetic anomalies (0-90 degrees; 3-4 degrees frequently)
• Altitude (negligible to 2 degrees)
• Secular change (2-25 years/degree)
• Diurnal change (negligible to 9 degrees)

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• Solar magnetic activity (negligible to extreme)

Location has an obvious effect as magnetic declination varies over the
entire globe. Each position on the Earth has a particular declination. The
change in its value as you travel is a complex function. If you travel
along a straight line of equal declination, called an isogonic line, it
varies little over thousands of kilometres. However, if you cross
isogonic lines at high latitudes, or near magnetic anomalies, the
declination can change more than one degree per kilometre.

Local anomalies originating in the upper mantle, crust, or surface,

distort the WMM or IGRF predictions. Geologic features include the
following:

• Ferromagnetic ore deposits

• volcanic structures, such as dikes and lava beds
• topographical features such as ridges, trenches, seamounts, and
mountains
• ground that was hit by lightning and possibly harbouring fulgurites
Cultural features include the following:

• power lines, pipes, rails, and buildings

• personal items, such as a steel watch or belt buckle, which can
cause an error of three to four degrees
In some places the field is completely vertical and a compass will
attempt to point straight up or down. For example, at the magnetic
dipoles, but there are other locations where extreme anomalies create the
same effect. Around such a place, the needle on a standard compass
drags so badly on the top or the bottom of the capsule that it cannot be
steadied.

The effect of altitude is normally negligible. According to the IGRF, a

20,000 meter climb even at a magnetically precarious location as
Resolute, NWT, Canada (500 kilometres from the north magnetic pole),
results in a two-degree reduction in declination.

Secular change is the movement of the magnetic north pole itself. As

convection currents churn in apparent chaos in the Earth's core, all
magnetic values change erratically over the years. The north magnetic
pole has wandered over 1000 kilometres since Sir John Ross first
reached it in 1831. Its rate of displacement has been accelerating in
recent years and is currently moving about 24 kilometres per year, that
is several times faster than the average of 6 kilometres per year since
1831.

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The stream of ionised particles and electrons emanating from the Sun,
known as solar wind, distorts the Earths’ magnetic field. As it rotates,
any location is subject alternately to the lee side, then the windward side
of this stream of charged particles. This has the effect of moving the
magnetic poles around an ellipse several tens of kilometres in diameter,
even during periods of steady solar wind without gusts.

The resulting diurnal change in declination is negligible at tropical and

temperate latitudes. For example, Ottawa is subject to plus or minus 0.1
degree of distortion. However; in Resolute, NWT, Canada, the diurnal
change cycles through at least plus or minus nine degrees of declination
error. This error can conceivably be corrected, but both the time of day
and the date have to be considered, as this effect also varies with
seasons.

The solar wind varies throughout an 11-year sunspot cycle, which itself
varies from one cycle to the next. In periods of high solar magnetic
activity, bursts of X-rays and charged particles are projected chaotically
into space, which creates gusts of solar wind. These magnetic storms
interfere with radio and electric services, and produce dazzling auroras.
The varied colours are caused by oxygen and nitrogen being ionised,
and then recapturing electrons at altitudes ranging from 100 to 1000
kilometres. The term geomagnetic storm refers to the effect of a solar
magnetic storm on the Earth.

For wellbore magnetic survey instruments other conditions that can

affect the measurement of wellbore azimuth are:

• Nearby Casing for example at KOPs

• Drillstring Magnetisation
• Nearby Offset, P&A’d or Junked wells

Graphic Offset Wells

The Offset Well selector enables you to select offset wells to be seen
from current Live Graphs, Wallplots or to be included in an Anti-
Collision scan. Within Compass, there are actually two Offset Wells
dialogue: one for Graphics and another for Anti-Collision. This section
only describes the features available within the live views and wallplots.

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The following graphic depicts the Graphic Offset Wells window:

Sites < 25km enables

wellpaths from sites
within other Fields and
other Companies to be Site, Well & Wellpath Lists
included within plot enables user to manually select
assuming same which wellpaths from current Field
geodetic system is appear in plot. The user can select
used individual wellpaths, all wellpaths
within a well or all wellpaths within
a site. The technique is simple:
double-click on a wellpath, well or
site to select/de-select

Include Principal Plan enables

Filter Offset Wells user to include principal plan of
enables user to restrict each wellpath included in offset
offset wells to those of wells. Useful technique for
certain types and/or comparing planned against actual
within a given range of trajectories
current wellpath

Double-click items in lists to select whole sites, wells, or wellpaths.

Selected wellpaths are indicated by a plus sign (+) in front of the name.
Those sites and wells that have one or more wellpaths selected are
shown with a plus sign. Non-selected items are indicated with a minus
(-) sign.

Include Principal Plan

If you want to compare an as-drilled Definitive Wellpath against the
proposed principal plan for that wellpath, click the Include Principal
Plan checkbox.

Filtering
Filtering enables you to quickly select which wellpaths to include in live
graphs or wallplots. You can filter by Type, Range, or All Wellpaths.

For a more complete description of the Offset Wells dialogue, see the
Anti-Collision section of this manual.

Import/Export
COMPASS is designed to enable data sharing between disciplines with
a number of different tools available to share different levels and types
of data.

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Compass Transfer Files

COMPASS enable a user to transfer data from one database to another.
This enables engineers to copy data to another engineer or site without
having to copy the entire database, for example Rig to Town, Town to
Rig, etc.

The COMPASS transfer file contains raw COMPASS data, not actual
reports or plots, and can only be imported into another COMPASS
database of the same version as the source database.

A user can create the following three types of transfer files:

• Field level
• Site level
• Well level

Field Level Transfer Files

Field level transfer files contain all field, site, well, and wellpath data in
the current field, as well information of the company that the field
belongs to. Importing a field level transfer file automatically creates the
company to which the field belonged in the source database to the target
database if it is not already there. A good naming procedure is to prefix
a Field level transfer file with ‘f_’ e.g. f_swfateh.cfw.

Site Level Transfer Files

Site level transfer files contain site, well, and wellpath data in the current
site. Importing a site level transfer file automatically creates the
company and field o which the sites belonged to in the source database
if it is not already there. A good naming procedure is to prefix a Site
level transfer file with ‘s_’ e.g. s_ll.cfw.

Well Level Transfer Files

Well level transfer files contain all well and wellpath data in the current
well, along with the company, field, and site that the well belongs to. If
the well exists in the target database, it is overwritten by the transfer file
data.

Rigsite users should only export data from COMPASS at this level.A
good naming procedure is to prefix a Well level transfer file with ‘w_’
e.g. w_ll10.cfw.

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Well Level Transfer Files - Empty Databases

If the target database is blank, the well and wellpath data are created,
along with the company, field, and site information to which it belongs.
If the site, field or company already exists, it is not affected by the
import.

Recommendations
It is strongly recommended that a particular operation clearly define
data transfer procedures with COMPASS to prevent data being
overwritten at the central data store. For example, if a rigsite exports at
the Field level but only has data for their current well/wellpath and the
Town site imports that file they would lose all other Field level data that
they possessed. Central sites should never import non-Well level
transfer files unless they know the file contains more up to date data for
the entire Field or Site than their own.

Limitations
• In both field and well level transfer files, only the target(s) assigned
to a wellpath are included in the export file. Unassigned site level
targets not included.
• The import process ignores Locked Data flags to ensure the
following:
• locked companies can add tools
• locked sites can add templates, targets, and datums
• locked wellpaths’ casing, formation, annotation, and history data
can be changed
• locked surveys can be changed
• locked plans can be changed
• When importing well level transfer files, any data in the target
database not associated with the wellpath in the transfer file is
overwritten.

Other Requirements
When you import well level transfer files you must have write access to
the well defined in the export file.

All dialogues, forms, and views need to be shut down before an import
can occur.

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To create a transfer file:

1 Open the desired company, field, site, well, and wellpath.

2 From the COMPASS main menu select File, Export Field, then
Site or Well.
3 Type a valid DOS file name. Use the Drives and Directories boxes
to change the drive and directory.
4 Click OK.

The file is generated. A progress indicator box displays the export

status.

To import a field or site level transfer file:

1 From the COMPASS main menu select File, Import, then

Transfer File.
2 If necessary, select the correct directory location using the Drives
and Directories boxes.
3 Click the desired transfer file.
4 Click OK.

COMPASS determines the type of transfer file (Field, Site or Well),

then generates a warning message informing you that any existing data
on the Target database is overwritten with what is on the disk.

5 Click OK to accept the transferred data.

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To import a well level transfer file:

1 Ensure you have write access to the well that is contained in the
transfer file.
Note:

You do not need to have the well, company, or field open.

2 From the COMPASS main menu select File, Import, then

Transfer File.
3 If necessary, use the Drives and Directories boxes to locate the
correct directory.
4 Click the desired transfer file.
5 Click OK.

COMPASS determines the type of transfer file (Field, Site or Well),

then generates a warning message informing you that any existing data
on the Target database is overwritten with what is on the disk.

6 Click OK to accept the transferred data.

Import DOS COMPASS Data

This import routine was built to assist customers migrating from the old
DOS version of COMPASS to COMPASS for Windows. COMPASS
for Windows has a Company / Field / Site /Well / Wellpath data
hierarchy. In contrast DOS COMPASS has a Field / Site / Well
hierarchy. When you import data from DOS COMPASS you may want
to create a new Company in COMPASS for Windows.

The import utility enables you to import an entire Field or Site or just
one Wellpath (survey or plan).

Import must first find the location of the RESIDE file. The RESIDE file
details the DOS path to COMPASS data. The RESIDE file is stored in
the same directory as the executable files (*.EXE). In most cases this is
in the C:\COMPASS directory.

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The following graphic depicts the Import DOS COMPASS Data

window:

To import from DOS COMPASS:

1 Click Directory and change directories until you locate the

RESIDE file. When you have located it, COMPASS displays a list
of Fields in your DOS COMPASS system.
2 Click the Field name to display Sites in that Field.
OR
Double-click the name to import the entire Field. At this stage you
can import the list of survey tools and associated errors contained in
the ERROR.PAR file.
3 Click the Site to display surveys and plans.
OR
Double-click Site name or Platform to import the entire Site.
4 Double-click a Survey
OR
Click Survey File to import a single survey.

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Wellbore Planner Import / Export

Wellbore Planner is a well planning application integrated in
Landmark’s Geological and Geophysical visualisation UNIX
applications. Links with COMPASS enable Wellbore Planner users
(Geologists/Geophysicists) to quickly construct well trajectories with
COMPASS users (drillers) with both using their own data sets. This
reduces planning time by eliminating the paper stage in which
geologist’s targets details are written down, passed to the driller, and
their resultant wellpath trajectory then copied back and forth until a final
trajectory is agreed upon.

COMPASS can import and export data directly to Wellbore Planner

version 1.1. This route also enables selective import of Openworks well
trajectories. This type of tool enables Planned Trajectory or Actual
Trajectory data to be easily shared between the Engineering and
Geoscience disciplines.

Wellbore Planner Import

Imports ‘*.WBP’ files from the Wellbore Planner application. The file
has to be moved to the Windows Compass Computer by FTP link.

These are the import rules:

• If you are moving the data to an existing Company, Field, or Site

open them before the import.
• If the import should not interfere with existing data, open a new
company. To open the file open dialog, from the COMPASS main
menu click File, Import, then Wellbore Planner. Select the file to
import (*.WBP).
If you are importing to an existing site a message box appears displaying
the following:

Click this... To import this...

All Data All data

WP Plans Wellbore Planner plans only

OW Wells OpenWorks wells surveys

If you have already chosen a site, the following message appears:

• Importing file xxxx.wbp to site yyyy, click OK to continue.

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If the Map coordinates contained in the Wellbore Planner file disagree

with the current site or disagree within itself the message Well xxxx has
strange starting coordinates appears. The data is still imported, but you
must check it.

Wellbore Planner Export

Exports a file in the Wellbore Planner format for import to a Geological
application like Open Vision. The file has to be moved from the
COMPASS for Windows PC by FTP. In Compass open the Customer,
Field, and Site of interest. Then, from the COMPASS main menu select
File, Export, then Wellbore Planner. COMPASS then asks the name
and destination location of the export file.

DIMS for Windows Survey Import

DIMS for Windows (DFW) is Landmark’s Drilling and Well Services
Daily Drilling and Completions Reporting System. Typically DIMS is
used at the rigsite as part of a client’s daily drilling reporting procedure.
Built in links between COMPASS and DIMS for Windows enables easy
transfer of survey information from DIMS to COMPASS to reduce
survey data entry duplication.

To access the DFW survey import tool, you must open a wellpath in
Compass to import surveys into. The DFW survey import also requires
an ODBC data source that you use to access the DIMS for Windows
database. A database connection is the PC’s mappings of how software
applications should open a database. Both COMPASS and DIMS for
Windows require defined ODBC connections before the applications
run. Consult your systems administrator to build a DIMS for Windows
ODBC data source if one is not available.

The following graphic depicts the DFW to Compass Survey Import

window:

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When all DIMS tools

have been mapped to
DIMS wells Compass equivalents,
can be the OK button becomes
selected from active. Press OK to
a picklist import the surveys

DIMS Survey Tools

Select the
must be mapped to
DIMS
Compass equivalents.
sidetrack
Compass tools are
(wellpath) to
available from a picklist.
import
All mappings are
surveys from
remembered for the
next import from DIMS

Well
Select a DFW well from the combo-box. COMPASS populates the
SideTrack list box with the sidetracks for that well defined within
DIMS.

Sidetrack
Select a DFW sidetrack for Compass to import Surveys from. Each
unique survey tool within DIMS for the sidetrack will be displayed in
the Tool Mappings grid.

Tool Mappings
The DFW survey tools must be mapped to equivalent COMPASS
survey tools. This is necessary because there is no connection between
them and COMPASS requires a correct tool mapping to calculate
positional uncertainty. You must do this for all DFW tools before
starting the import. COMPASS remembers survey tool mappings for
future use.

When mappings are complete, press OK and COMPASS imports the

DIMS for Windows data creating a separate survey for each one of the
mappings.

Data Exchange
DEX is the data exchange format for Landmarks Drilling & Well
Services Applications. It is a document-based file transfer method using
an open protocol. The file contains a number of business objects (data
entities) depending on which application generated the file.

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For example, here is a list of business objects recognised and populated

by COMPASS:

• Well
• Location
• Directional Survey
• Formation Tops
• Casing Shoes
These can be communicated with applications that have DEX enabled:

• Casing Seat - Casing seat selection.

• StressCheck - Casing Design.
• Wellcat - Advanced thermal model for completions design.
• DrillModel - Well costing.
• Wellplan - Drillstring design, torque drag, hydraulics, well control
and cementing.
• DIMS - Daily drilling reporting and analysis system.

Note:

The DEX business objects do not include survey tool

error model information. Surveys imported from other
applications should have error models assigned to them
so COMPASS can correctly model positional
uncertainty.

To export a DEX file:

1 Right-click a wellpath in the browser, select Export, then DEX.

2 Select the target file name and click OK. This exports all data
objects that COMPASS can provide data for from the wellpath.

Or

• From the COMPASS main menu, select File, Data Exchange, then
Export.

This method outputs data from the currently opened wellpath.

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To import a DEX file:

1 Right-click a wellpath in the browser, select Import, then DEX.

2 Select the source file name then the business objects that you want
to import to the wellpath.
3 Click OK to begin the import process.

COMPASS can import the following business objects:

• Formation tops.
• Casings. If any casings are imported, COMPASS gives you the
option of adding them to the definitive path.
• Surveys. At the start of the survey import, you are told how
many COMPASS surveys the import creates and they are asked
if you want to update the definitive path with the imported
surveys. At this point you can cancel the import, import the
surveys, or import the surveys and update the definitive path
with them.
Warning:

After the business object selection dialogue is confirmed,

COMPASS does not ask for further confirmation to
overwrite existing data. Any casing, formation or survey
whose name matches one of the imported DEX objects are
overwritten.

To browse a DEX file:

1 From the COMPASS main menu, select File, Data Exchange, and
then Browse.

This launches the standard DEX browse window, which displays the
last DEX file imported or exported.

2 Examine the structure and contents by expanding the branches in

the browse tree.

This is a useful process to determine the contents of the DEX file

before importing it.

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Survey Module

Introduction
The Survey module calculates drilled wellpath trajectories from entered
survey data using the company specified survey calculation method
such as Minimum Curvature. The module can be used to enter
traditional survey data (MD, Inc. & Azi), Inertial Survey data (TVD, N,
E) and Inclination Only survey data (MD, Inc.). Using an assigned
survey tool error model for each survey, the wellpath positional
uncertainty over the depth range of the survey can be calculated and
included in the definitive wellpath to be used in anti-collision
calculations.

The main components of the Survey module are -

• Survey Setup
• Survey Import
• Survey Editor
• Project Ahead and Interpolate
• Quality Assessment tools
• Survey Analysis
• Survey Reports
• Survey Export
Setup is used to enter the survey tie-on point, assign a survey tool and
import survey data from a text file or the Windows clipboard. The Editor
lets you type in survey measurements, compute the wellpath trajectory,
and project ahead from the last survey point to a target location, depth
on a plan or calculate a trend using existing survey data to a MD or TVD.
You can also interpolate points on the survey by either MD, TVD, Inc.
or Azi. Quality control tools enable a user to check for the presence of
errors in the data that can be immediately corrected.

Analysis tools enable creation of comparative T-Plot charts as well as

assessment of survey data quality using graphs or reports. Survey
Reports let a user create their own pre-defined reports or preview canned
report formats supplied with COMPASS. Export tools enable survey
data and almost all other data available within COMPASS to be

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exported in a variety of user defined formats to a text file or the

Windows clipboard.

Survey Setup
Before creating a new survey check the Status Box to ensure you are
entering the survey into the correct Company, Field, Site, Well and
Wellpath. To create a new survey, from the menubar select Survey then
click New Survey, or right-click in the browser with the Surveys box
highlighted under the Wellpath name. A menu appears with New Survey
at the top.

The most important items in Survey setup are the name, survey tool
assigned and the tie-on point designation. An intuitive survey naming
convention should always be adopted and supported within a company
so that unfamiliar survey data can be easily recognized. Two good
recommendations are to include the hole size the survey tool was run in,
as well as the tool name itself. Examples of easily recognizable survey
names are:

• 12-1/4” Sperry-Sun MWD

• 9-5/8” Finder Gyro (0hr)
• 13-3/8” Keeper Gyro in Csg
• 26” Totco
You can also enter Description, Company and Engineer details to
provide additional information about the survey although this is not a
system requirement. Company and Engineer fields are populated
automatically with your name and Company name when a new survey
is created.

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The following graphic depicts the Survey Setup window:

Ensure that the survey is given an intuitive name

to help other engineers reference it

Click here to import survey stations

automatically from a text file or through the
Windows clipboard
Select the survey tool filtering by type from the
list of tool error models defined within the
Company. Note: the default tool is automatically
selected.
Tie the survey to the wellhead, a user defined
point in space or to any depth along the definitive
path or another survey

To prevent unauthorised changes to the Survey,

lock it!

Other parameters are:

In this field... Do this...

Start Date Enter the date that the survey commenced.

This date is recorded in the survey program.
Open menu and click to
enter today’s date.

Survey Type The survey type filters the survey tool type
selection. The following two survey types
have additional functionality:
• Inertial - Imported surveys that do not get
re-calculated.

• Inclination only surveys (e.g. TOTCO)-

Surveys with no azimuth column.

Tool Type Select the type of survey instrument from the

survey tool sub-list of filtered on type, select
the tool that surveyed this section of wellbore.
If the survey tool is not on the list you should
create a new tool.
Important - The survey tool you assign
determines the error radius around the
wellbore for anti-collision purposes. If you do
not specifically assign a survey tool
COMPASS assigns the default survey tool
which is probably not correct.

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Chapter 6: Survey Module

In this field... Do this...

Locked A locked survey can be recalled but can not

be edited. If you have entered a locked data
password you are asked to enter this before
unlocking. It is a good idea to lock surveys
whenever possible to avert the chance of the
data becoming changed, deleted or corrupted.
If in doubt, lock it!

Audit Info Enter additional notes regarding how the

survey was run, quality checks performed
against the survey, any other information that
you’d like recorded against the survey

Tie-on Point Options

There are three choices of tie-on point methods. The tie-on point can be
defined explicitly, tied to the wellhead location, or calculated based on
a specified measured depth. Note: if starting a sidetrack you should
create a new wellpath first.

You may select a different survey to tie-on to from the combo box. The
start point (tie-line) items are as follows:

This start point... Does this...

MD Starting measured depth for the survey.

Inc. Starting inclination from vertical. Vertical is

zero degrees.

Azi Starting direction from Local North.

TVD True vertical depth measured from the

selected Datum.

N/S North distance from the local coordinate

centre.

E/W East distance from the local coordinate centre.

There are three choices of tie-on point methods. The tie-on point can be
defined explicitly, tied to the wellhead location, or calculated based on
a specified measured depth. Note: if starting a sidetrack you should
create a new wellpath first.

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User Defined
Type in the coordinates and depth of the start point. This is attaching the
survey to a free point in space. No checks are made to ensure the validity
of this tie-on point. It is assumed that you know why you are using this
method.

User Defined - you may define all the

values of the tie-on point. Nothing is
calculated for this point.

From Wellhead
COMPASS starts the survey at the N/S E/W coordinates of the wellhead
or slot location. You can still specify inclination and azimuth should the
start point be non vertical. Note - If in Company Setup you set the local
coordinate origin to slot, the survey tie-on coordinates are set to 0 N/S
and 0 E/W and do not inherit the well coordinates.

From Wellhead - extracts the N/S, E/W

local coordinates from Site Centre as
defined in Well Setup

From Survey
Ties on to the last point on the definitive wellpath or a selected survey
by default. You can specify another measured depth to interpolate from
the within the survey/definitive wellpath.
From Survey - enter a MD from within the
Survey or Definitive Wellpath and COMPASS
will interpolate the other values

Survey Import
COMPASS enables survey data to be imported from other sources. For
example, from the survey contractor at the rigsite or directional drilling
office. The Survey Import feature is one of the best tools to reduce errors
in the survey data entered into COMPASS by eliminating the potential
for typing mistakes when survey readings are re-entered. It is designed
to be flexible and easy to use.

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To import survey data, click Import Survey Data.

To import survey data, you must know exactly how the survey data is
formatted in the source data location. Normally, the COMPASS user
would agree to a format with the survey hand/contractor or the operator
can simply dictate exactly what the format should be. The following
graphic depicts the Import Survey window:

Import survey data from a Text

File or the Windows Clipboard

Choose the type of survey

data to import Inclination Only data will
be imported. COMPASS
Define the column order of will calculate TVD but not
the data table you are going Azimuth N or E.
to import

Select the appropriate units of To complete the import

the source data set. COMPASS format select Blank/Tab as
will convert the data as it is the column separator, or
imported to the current unit set simply type it in
configuration if necessary
Define the numeric
delimeters used for
countries where commas
are used as decimal
separator

COMPASS is capable of importing different types of corrected and

partially corrected survey data. COMPASS can read in the survey
observations and is capable of applying minor corrections to the data as
it is imported.

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Different types of surveys that can be imported are:

This survey... Shows this...

Normal Survey A survey consisting of MD, Inclination and

Azimuth. From this, COMPASS computes the
TVD, N/S and E/W of each survey station.

Inertial Survey A survey consisting of MD, Inclination,

Azimuth, TVD, N/S and E/W. COMPASS
reads the coordinates (TVD, N/S and E/W) of
each survey station. MD, Inclination and
Azimuth are not back calculated.

Inertial Survey A survey consisting of 3 columns TVD, N/S

Calculate MD/Inc./Azi and E/W. COMPASS reads the coordinates
(TVD, N/S and E/W) of each survey station
and back calculates the MD, Inclination and
Azimuth.

Inclination Only A survey consisting of MD and Inc. only.

TVD is calculated but not Azimuth, Northing
or Easting of the wellpath.

Other parameters that are required to specify the import survey data
format are:

Column order
Enter the order read from left to right of the data to import. For example:

MD Azi Inc

5400 321.5 15.4

5500 321.6 15.7

5600 321.3 15.5

…would be imported as a normal survey with column order 1, 2, & 3.

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Chapter 6: Survey Module

Units

Use... To...

Depth Select feet or meters for the trajectory units

Inclination Select from the available list, usually degrees

Azimuth Select from the available list, usually degrees

Column Delimiter

This delimiter... Is described as...

Blank/Tab What separates the columns, a blank space or a tab

or....

User Type in some other character e.g. semi-colon,

comma.

Data Source

Either:
• Select the text file to import. You are able to use a standard
Windows file section dialogue. Find the file, select it, press OK,
then COMPASS reads the data and reports how many valid
survey observations were found.

• Data can be pasted from the Windows clipboard. You could

copy data from a Word document or Excel spreadsheet and paste
the data directly into COMPASS.

Correction
Three correction fields exist next to the Units selection. These allow the
correction of survey values as they are imported. This is the only area
within the software that does not assume that the survey data entered
into COMPASS has been corrected by the survey contractor. Normally,
the survey contractor would complete all corrections utilizing their own
software prior to make the survey data available. Note: negative values
can be entered into these fields.

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Use these tools with care, otherwise the survey data can become
corrupted.

Add to MD
Add the value to all measured depths in the input file. This could be
used where the depths have been measured to a different datum than
the current wellpath datum. For example, the current wellpath datum
is RKB, but the import data has been referenced to Mean Sea Level.

Add to Inc
Add the value to all inclinations in the input file. This correction has
been included for completeness. In rare circumstances, survey data
can be corrected for inclination where the survey instrument has a
known offset orientation from survey tool centre-line.

Add to Azi
Add the value to all azimuths in the input file. This should be used
where the incoming data has been measured to a different North
reference than the current site. Apply the difference in declination or
convergence as appropriate.

Whatever the data location or format, COMPASS survey data import,

reads only the data from rows in the source location that have the correct
format. Any rows in the source location that do not have the exact
specified format are ignored. This is quite useful as it means that other
parties can include survey header information such as column titles and
units or other notes about the survey data that is passed over during the
import process.

Note:

The only method available to modify Inertial Surveys is

to convert them to equivalent MD, Inc, Azi prior to
importing them into Compass or exporting/re-importing
as MD, Inc, Azi. Once entered into Compass, the Survey
Editor does not allow Inertial Survey data to be modified,
it is read only.

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Survey Data Editor

The Survey Editor is essentially an enhanced spreadsheet with built in
survey calculation functionality. The spreadsheet enables surveys to be
easily edited, viewed and forms an area where additional tools can be
launched. Note that if a survey editor is open, any live views highlight
the depth range of any survey data entered.

Some general rules apply to the Survey Editor:

• To insert or delete a row you must first select the row.

• To select a row press the left arrow until the row is highlighted by a
black bar or click the grey numbered column on the left hand-side
of the survey editor.
• When you have selected a row press your keyboard's Insert key or
Delete key.
• The first row, row 1, is the tie-in point that is defined in Survey
Setup and can not be changed in the survey editor. It can only be
changed in Survey Setup.
• The current MD (Measured Depth) must be greater than the
preceding MD.
• Inc (Inclination) must be in the range 0-180 degrees.
• Azi (Azimuth) must be in the range 0-360 degrees.

Automatic MD
If you press enter without typing in a new MD, COMPASS
automatically increments the MD.

If you are incrementing from the first line the amount is 100 feet, unless
depth units are metres, in which case it is 30m. If you are incrementing
from subsequent lines the additional MD is computed from the previous
two lines.

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The following graphic depicts the Survey Editor Spreadsheet:

Interpolate the current When Input Validation is checked any The average tortuosity over the range off the
survey by MD, TVD, Inc or Doglegs above... survey is displayed here. This value may be
Azi used for Torque/Drag tortuosity modelling
.... this value will be highlighted in red

From the last survey point

project ahead to

• see existing directional

trend
• determine directional
parameters to hit target
• perform back-on track cal-
culations to plan
• perform look-ahead anti-
collision

ress the Tab button on the

eyboard to move to next
ell in grid

To delete a row, click on the row number in the grid and press the keyboard Delete button.
To a row, highlight row above which you want to insert and press the keyboard Insert button

Once you have entered or imported the survey it is good practice to save
it right away and then complete a Varying Curvature scan to check for
poor quality surveys.

Interpolation Window

The Interpolation window enables a number of points to be interpolated

along the survey at any measured depth, true vertical depth, inclination
or azimuth. You can enter as many points as you require into the
interpolation grid at a time. All results are referenced by default to the
current wellpath datum, but this can be changes to any available site
datum.

This is a useful data sharing feature as engineers in different company

departments could use a particular datum for their own well analysis.
For example, production engineers could reference the wellhead to
define their production string component or perforated section depths.

Results are available by clicking on the Notepad icon at the bottom of

the window. This enables the interpolated results to be printed,
incorporated into another document via the Windows clipboard, faxed
or emailed.

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The following graphic depicts the Survey Point Interpolation Window:

TVD results/entered values are displayed Results are available in text format using the Windows
relative to the Field Vertical Reference Datum Notepad feature. This may be printed, copied to
clipboard or sent/emailed to a colleague

Within the current survey can interpolate by MD, Inc, Azi or TVD. For each method,
the other entry parameters plus N/S, E/W, VSec and DLS are calculated

Note that the Interpolation algorithm used is determined from the

Calculation method specified in Company Setup. This is also true for the
Definitive Wellpath Spreadsheet Interpolation tool and the Casing,
Formation and Annotation editors.

Depending on the calculation method you might get some unexpected

results. For example, Minimum curvature uses the ’great circle route’
between 2 survey stations. If the 1st station was at 1 deg inclination with
heading due north and the 2nd survey station had 1 inclination deg due
south. Minimum curvature would track the path going under itself
(round the sphere), hence the point 1/2 way would have zero inclination!
Radius of curvature tracks the path going round the cylinder (like a
spiral), so all intermediate points would have the same inclination, and
azimuth would go 0 to 180. But minimum curvature has the least overall
angle change. You can prove the same thing in planning by using
Dogleg/ Toolface to the same inclination - the interpolated inclinations
will dip in the middle, whereas the Build/Turn equivalent will maintain
a constant inclination.

Project Ahead
Project Ahead is a very useful survey tool to determine whether a
wellpath currently being drilled is on course to hit a target or project to
a MD or TVD using a set of directional drilling parameters. If it is

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determined that the wellpath is not on course, Project Ahead can be used
to determine what is required to get the wellpath back on track to a plan
or directly to a target. Directional drilling parameters for both rotary and
steerable drilling assemblies can be determined.

The projection is made from the last observation in the open survey, plus
the initial hold length. Should stations be added to the survey, the
projection recalculates from the end of these. If anti-collision is
currently being used, then the projection is included in the current anti-
collision scan to enable ‘look ahead anti-collision’.

The following graphic depicts the Project Ahead Window:

Results are available in text format using the The target aiming point can be
Windows Notepad feature. This may be printed, adjusted laterally and vertically
copied to clipboard or sent/emailed to a colleague

Project Ahead to An Object:

• Target
• Formation
• Back on track with Plan
... or calculate a User Defined
Projection using: Select the projection type:
one section, two sections or
• Dogleg/Toolface three sections
• Build/Turn
• Trend calc’d from survey

Enter values here for the

projection, depending on what
method is selected
Will apply a hold or calculate
a trend for this length before
computing doglegs to hit the
targets or define trend

The Project Steps grid

displays the results (below) and The target point with the lowest drop
the trajectory determined for the rate or highest build rate
hold section The target point with the biggest drop Curve Only results to a
rate or least build rectangular target
The target point with the greatest right turn
The target point with the greatest left turn

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Project Ahead can operate in one of two ways:

Use the... If you want to...

Project To Target / Plan or Specify the required location and let

Formation COMPASS compute the trajectory changes
using one of the trajectory types. If the current
wellpath has a principal plan, it shows the
actions required to take the wellpath back to
the plan. This also works for dipping
formations.

User Defined Projection - Curve Specify the projection distance to a MD or

Only TVD and the curve rates and then let
COMPASS compute the new location.

Two other areas in the window complete the dialogue. The parameter
entry area enables You to enter MD, TVD, Dogleg/Toolface, Build/
Turn values as required by the projection method. Below lies the results
grid that displays the directional drilling parameters of one or more
projected sections.

The following graphic depicts the Project Ahead Parameters Area:

Initial Hold Length

Whether projecting to target or a free projection you can apply an initial
hold section to represent the already drilled wellbore behind the bit. This
is especially useful when you consider that the survey instrument can be
50ft or so behind the bit. Compass enables a user to include a hold
section with 0.0 deg dogleg through this interval or a trend can be
calculated from adjacent survey data. This section is included in the
Projection Steps grid.

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Project To Target / Plan or Formation

The following graphic depicts the Project to Target or Plan Area within
Project Ahead:
Select a Target, Formation or Plan Select a Target from the Site list currently
defined within the current wellpath selected by the current wellpath

If projecting to a target, override

the target’s aiming point by
selecting a new location vertical
or laterally using the Target
Landing Adjust feature

Choose a Wellpath Projection Type:

• Curve Only - Single section: continuous steering to the Target/Plan

• Curve+Hold - Two sections: steer to line up on Target then hold to
hit the Target
• Optimum Align - Three sections: steer, hold, then steer again to line
up on target or align wellpath back with the plan

1 Select the Object to Project to:

• Target: Select a target from the target list or enter a point to aim
for. If you don't see the required target on the list you cannot
have allocated it to the wellpath list. When a target is selected,
the tabular display is updated and shows the requirements to hit
five extremity points on the target for Curve Only or displays
the projection sections for Curve-Hold and Optimum Align.
Projecting to a target enables the use of the Landing Point adjust
feature in the Target Viewer. Click on LANDING and the Target
Viewer appears that enables you to select any point to Project
to.
• Plan / Formation: Select the principal plan or the formation to
steer into. This method not only returns the wellpath back to the
plan, but also directs the well so that it aligns with the correct
inclination and azimuth.
2 Choose the Wellpath Projection Type to get to the point:
• Curve Only: Projects a single curve to the target or plan point
through continuous steering. COMPASS calculates the dogleg
required for the projection.
• Curve and Hold: can be used for slant wells and sidetracks
where the intercept point is close to the target. Curve+Hold
adds two sections. The curve gets you aimed at the plan/
formation and then holds until it’s been hit. While this method
returns you to a point on the planned wellpath it does not align

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Chapter 6: Survey Module

you with the direction and inclination of the plan.

Curve + Hold requires the dogleg severity for the curve to be
entered in the parameter fields below. If not entered, a
Projection Warning window displays, explaining that it is not
mathematically possible to project to the required point.
• Optimum Align: Method is best applied to horizontal wells
where full steering control is possible. Optimum align adds
three sections - curve / hold / curve. This not only returns you to
the planned wellpath but when you select the plan you are on,
the planned inclination and correct azimuth displays at that
point. This projection also requires the dogleg severity for the
two steered sections to be entered.
3 You need to set the measured depth to reach the plan to intercept it,
and the dogleg severity to use in steering. If you specify a measured
depth that is too short to reach the plan, the program cycles depths
in 10' (5m) increments until the plan can be reached.
4 When all parameters are defined, click Calculate to generate the
Projection. Depending on what has been requested, one or more
rows appear in the results grid. Projections to targets can display
parameters to hit different points on the target, projection or
projections to user selected aiming points. Curve+Hold and
Optimum Align projections display section details. All rows in the
results grid display the Build & Turn rate required for rotary
drilling assemblies, Dogleg/Toolface required for steerable
assemblies and the projected point including MD, TVD, Inc, Azi,
N, E and Vsec.

The following graphic depicts the Project Ahead – Optimum Align to

Target results:

The Projection Steps results grid also displays the directional

parameters calculated for the hold section, whether hold or calculated
for trend. This information is very useful to a directional driller who
includes the information when setting up their tools for a slide.

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Click Notepad in the tool bar to make Projection details available

as a text file that could be shared with other engineers.

If the object projected to is a target and the Projection is Curve Only,

COMPASS displays a number of Projections to hit different locations
on the target:

The following graphic depicts the Project Ahead results to Target for
Curve Only:

You can interact using the Live views and the different projected
sections. Clicking on a row in the results grid results in that projection
being displayed in all live views.

User Defined Projection - Curve Only

User defined projections enable ‘what if’ type projections to be
completed to a MD or TVD through continuous steering only. For rotary
drilling assemblies, You can define Build and Turn rates; for steerable
drilling assemblies You can define a Dogleg and Toolface Orientation.
To determine if a wellpath is on course to a target or other location, a
trend can be established from a number of existing surveys to a MD or
TVD.

The following graphic depicts the User Defined Projection in Project

Ahead:

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Chapter 6: Survey Module

1 Select the Depth to Project to:

• MD—Measured Depth
• TVD—Vertical Depth

Depths must be entered into the parameter entry fields below.

2 Select the Projection Type:

• Build & Turn Rate (for rotary drilling).
• Dogleg Rate and Tool Face Orientation (for steering drilling).
• Apply the Trend over a number of previous survey points (to
continue the current trend) or Hold for a given Bit-Survey tool
distance. You can enter the number of survey points to construct
the trend directly or use the up/down arrows to change the
number of points.
3 Enter the necessary projection parameters highlighted in the line
below, the press Calculate.

The results grid populates and any live views are updated to display the
Projected section.

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The following graphic depicts the COMPASS 3D view displaying

Project Ahead Curve+Hold from a survey ending at circular target T1
projecting ahead to rectangular target T10:

Project ahead section from end of survey at target T1 to hit aiming point
on target T10.

Survey Data Quality

One of the more useful tools in COMPASS enables you to check for
errors in the survey data. The large amount of survey data typical of
modern surveys means that it is very difficult to visually assess whether
any errors are present and if they are, where they are located.
Unfortunately, Survey Errors are very common due to a number of
reasons that include:

• Typing/Communication (language) problems

• Inconsistent interpretation of survey measurements
• Bad individual survey
• Survey Tool operating incorrectly
• Survey Tool run badly
• Incorrect tie-on points

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Because of the large source of errors and potentially serious

consequences, every survey should be checked and ideally each
company should have some form of survey quality control procedure in
place to ensure that these errors are detected. Remember, the survey
hand should be checking for errors too!

You can assess the quality of the survey data using Input Validation to
check for high doglegs or use the more rigorous Varying Curvature
method that checks for the individual effect that each survey observation
has on the calculated bottom hole location.

Both tools allow you to determine the depth of any suspect points that
can be fed back to the survey hand for them to check.

Input Validation
The Input Validation tool is an easily accessible on/off toggle and
dogleg severity entry field located to the bottom left of the survey editor
grid. When turned on, survey observation calculated dogleg severities
higher than the validation dogleg severity are highlighted in red with a
negative value to indicate that they should be checked. Remember, there
are valid reasons for high local doglegs such as controlled directional
drilling.

The following graphic depicts Input Validation in the Survey Editor:

If Input Validation is checked, then any doglegs greater than the 7.32 deg/100ft dogleg
entered value will be highlighted as a negative value in red highlighted in red

With the Input Validation tool on, the entire survey should be parsed to
check for suspect doglegs. If there is any question about a survey point,
get the survey hand to check it or delete the survey.

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Varying Curvature
Varying curvature considers the effect on the calculated bottom hole
location of each survey point by removing it from the survey and
recalculating the trajectory. For each station the calculated result is
called inconsistency which is the distance the calculated bottom hole
location would move if a survey observation was removed and is
expressed as a percentage of the adjoining survey’s depth interval. For
example, if the measured depth interval of your survey stations is 100ft
and the removal of an observation moves the bottom hole location by
5ft, then the inconsistency value of that observation is 5%.

The following graphic depicts the Explanation of Varying Curvature

algorithm:

To help filter out suspect observations, a Tolerance limit can be defined,

essentially a Quality Control level. Any observation above this tolerance
is plotted in red and summarized on the varying curvature report.

As a general rule any observations with an inconsistency greater than

2% are suspect. However good quality survey data with a very low mean
inconsistency can show suspect inconsistencies much lower than 2%.

Varying Curvature tools are accessed from the Data Analysis submenu
in the Survey menu of the COMPASS menubar or by right-clicking with
the mouse over the wellpath name in the browser. When accessed a
choice window appears. You can choose to review a varying curvature

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Chapter 6: Survey Module

report, fire up a 2D varying curvature graph, or a 3D varying curvature

graph.

The following graphic depicts the Varying Curvature Selection

Window:

Define Quality Level to be highlighted

in graphs or appear in reports

Varying Curvature Analysis Options:

• Create a Report
• Produce a graph of combined
inconsistency for each survey sta-
tion
• Produce a graph of Inconsistency
split into its vertical and horizontal
components

Varying Curvature Report

The Varying Curvature report displays the inconsistency of each survey
observation and highlights any observations with a calculated
inconsistency greater than the tolerance limit. The report can be printed
or saved to a file. Note that this report is the only report generated from
COMPASS that cannot be output to an ASCII file.

2D Varying Curvature Graph

The 2D varying curvature graph plots total inconsistency against
measured depth of the survey. It is an easy graph to interpret where all
one has to do is look for irregular spikes in the data, read off the depth
of the spike using the line data reader, then check the survey observation
data at that point. These graphs are live, so you can move the survey
editor to see both editor and graph, update the observation in question
and immediately assess whether the correction has removed the spike.

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The following graphic depicts an example of 2D Varying Curvature

Graph:
Use the Line Data Reader to see survey station
details of any suspect points within the survey

Despite being below the 2% threshold, it would be advisable to

check the survey measurements on both these stations

The example above displays two suspect points. Even though their
inconsistency is well below the tolerance, both of these points should be
checked with the survey contractor. It could well be that these survey
stations were reported incorrectly or were due to being incorrectly
recording by the survey hand.

3D Varying Curvature graph

The 3D varying graph separates inconsistency into it’s vertical (high/
low) and horizontal (left/right) components and plots it against
measured depth of the survey. Spikes in the high/low side graph are
mainly due to errors in inclination. Spikes in the left/right are mainly due
to errors in azimuth.

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The following graphic depicts 3D Varying Curvature Graphs:

Likely Inclination Error Likely Azimuth Error

The example above displays the two suspect points as an error in

inclination at 1496 ft. and an error in azimuth at 2923 ft. With this
information, one could phone up the survey hand to check the
inclination and azimuth at these depths and get them to report back if the
survey requires a correction.

Survey Data Analysis

Analysis Graphs enable the production of comparison plots of survey
and plan data. You can for example plot MD against inclination or
azimuth or Dogleg Severity against Wellbore Inclination to see how
well the directional driller is controlling direction as he builds angle.
Multiple surveys can be overlain to compare different surveys within the
same hole section, plot planned trajectories against actuals, or assess
survey variation against that defined by the survey tool error model.

A comparison of dogleg against MD can indicate areas of possible

casing wear, or indicate locations where keyseating can occur. Similarly
dogleg against TVD can indicate which formations were difficult to
drill.

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There are two options available, Min/Max graph or Analysis Graphs.

Max / Min View

You must have a survey open to gain access to Max / Min View. The
Min/Max view displays two graphs:

• Inclination against measured depth

• Azimuth against measured depth for the entire measured depth
range of the current survey
Additionally, the title area details the range of inclinations and azimuths
present in the survey data. This graph can be useful as a first quality
control check on survey data. However, varying curvature scan offers a
more rigorous method of identifying poor survey data.

Analysis Graphs
To create analysis graphs, first open the survey you wish to plot, then
choose Analysis Graphs from the Data Analysis submenu in the main
Survey menu.

The next step depends on the type of analysis you require. You have a
choice of two types of graph selection. COMPASS is supplied with a
number of commonly used Predefined formats, mainly against
Measured Depth. In addition, User Defined plot formats can be
generated.

The following graphic depicts Pre-defined Survey Analysis Graphs:

Select parameters to cross-plot Choose between canned

from drop down selection lists comparisons or user defined
or define your own formats

You can choose to cross plot as many graphs as you like at a time but
this is realistically limited to the amount of vertical resolution required.
Too many graphs and it is difficult to interpret or even see any change
in the data in the graph.

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Like all COMPASS graphs, Analysis Graphs come supplied with the
usual toolbar icons, they can be printed or sent to Print Preview to see
what would be sent to the printer.

Plotting multiple surveys

Additional surveys can be included in an existing graph for comparison
purposes. For example, you can want to compare survey tool results
over the same section of wellbore to see if the extra time running a Gyro
survey was well spent.

Additional Surveys may be selected in the browser by selecting them

from the wellpath’s Survey list. Simply toggle specific surveys to
include them in any graphic.

The following graphic depicts the browser list with 3 additional surveys
selected:

Three surveys have been

selected to appear in all
active live views

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The following graphic depicts an Analysis Graph cross plot displaying

comparative survey data:

The above example is taken from the COMPASS training course. The
plot displays two surveys, an Electronic Multi-shot (EMS) survey and a
series of conventional SRG single shots, run over the same depth
interval. The top inclination graph shows that the well profile is build,
hold and drop – an S-well. It also shows no real difference between the
two sets of survey data. On inclination at least, the two surveys agree.

The second azimuth graph shows that the well is being turned slightly to
the right through the build section, then roughly holds direction until the
end of the survey. Looking at the survey data, one can see that as the
well builds angle, the surveys start to disagree and that it is the Magnetic
data which is displaying a higher azimuth. When the inclination starts to
drop, one can see that the magnetic data drops back into line with the
single shot gyro data. This type of behaviour would suggest that the
magnetic data is subject to some form of inclination driven interference
that is not affecting the Gyro readings – possibly the survey tool has
been poorly located and is being affected by drill string magnetization.
Alternatively once can see the sudden shift in the trend of the gyro data
at 1500ft and say that it is suspect from that depth. Whatever the reason,
the graph clearly shows that there is a difference in the survey readings
and that further investigation is required.

Relative Instrument Performance

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Expected measurement errors for Inclination and Azimuth axes may be

displayed on the analysis graphs by hitting the error bars button on the
toolbar or in graphic options. The quality of overlapping surveys may be
determined by evaluating the actual inclination and azimuth differences
against their expected performance shown by the error bars.

The error bars on survey analysis graphs are a combination of the errors
on both the reference survey and the survey chosen for comparison
(using RSS addition of independent sources of error). Note that the size
of the error bars is determined from the confidence level chosen for
Output Errors in customer set-up.

The following graphic displays a relative instrument performance:

Turn on error bars to see how the These graphs compare surveys, so at
survey tool performed against its least one additional survey needs to
defined error model be selected to see any results

The above graph compares the SRG and EMS surveys. Looking at the
Delta Inclination data, there is considerable variation between the two
surveys; however, no trend can be observed between them. When
comparing against the expected variation due to error, the variation is
greater than expected for the tool error models and the confidence level
defined within the company.

The Delta Azimuth graph displays a clear trend between the two surveys
again highlighting that one of the surveys is being affected by some

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physical effect which is not affecting the other survey. Survey errors are
almost within their expected margins.

Survey Reports
The Reports functionality within COMPASS provides a flexible, easy to
use, survey/directional well planning reporting mechanism suitable for
all users of directional drilling software. COMPASS comes supplied
with a number of canned reports, some that are of a fixed format. Report
Options and a Format Editor enable any client to build their own report
format to meet their requirements.

COMPASS offers five predefined survey reports:

Report Description

Survey Report (Local) Full featured survey report referenced to Site

Centre

Survey Report (Geog.) Full featured survey report referenced to

Geodetic System

Well Level Summary List of Surveys and Definitive Path for

current wellpath

Site Level Summary As above but for all wellpaths within the
current site

Template Slot Report Slot locations with allocated wells and

Geodetic coordinates

In addition to the standard reports, you can configure your own format

with or edit the provided examples in the bottom of the report

list.

Survey Reports are accessed from the main Survey menu or from the
icon in the COMPASS toolbar. Note that the reporting functionality is
available whether a survey is open or not. If the latter, then the report
details the definitive path; otherwise, the data for the open survey.

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Chapter 6: Survey Module

The following graphic depicts the Survey Reports Window:

To delete a report format no

longer required, highlight it in
the list and press the trash
can icon

All reports can be previewed and

printed in a professional format
using the Report Manager

or... they can be output to a text file

Report Options lets you select which New and Edit lets you create your
additional data to include in report and own report formats form scratch or
which MD/TVD reference datum to use modify and existing format

The fixed format reports are not editable. They are provided as examples
guaranteed to be available at all times.

Click... To...

Store the report to disc as an ASCII file. You can load

the resulting ASCII file into Windows Notepad, word
processors such as Word for Windows or into a
spreadsheet. See also Export Survey for how to create
your own export file formats.

Review the report on your window prior to printing.

Reports are viewed from the Report Manager and
configured to include company logos on the left and
right hand side of the title area. Note that these
company logos can be viewed from the Report
Manager as well.

Report Options

The Report Options window enables the report contents to be

customized to meet particular output requirements.

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The following graphic depicts the Survey Report Options Window:

Survey report TVD and MD can be

referenced to any of the available
Site datums

All Wellpath database can be

The interpolated point of the included in the survey report. Data
wellpath at TD can be included in can be interpolated by MD or TVD to
the survey table any interval or limited to a depth
range

Additional wellpath information Survey setup data and definitive

can be included in the survey wellpath information can be included
table included in the report in the report

Vertical Datum
You can adjust the True Vertical Depth on your survey report to any
datum defined within the site. The <Current Datum> is the wellpath
datum that is defined in Wellpath Setup. Different datum levels can be
defined in the Site Datum editor.

Interpolate
The wellpath can be interpolated at intervals of Measured Depth (MD)
or True Vertical Depth (TVD). If you select interpolation you must
specify an interpolation Interval.

Depth Range
Enter the start and end depth of the range to print. The range can be for
Measured or True Vertical Depths.

Specify Depths
If entering Interpolation intervals or Depth Ranges, you toggle whether
are for Measured or True Vertical Depths. If Interpolate and Range is
not toggled on, the MD/TVD toggles here are inactive. Additionally,
you can select additional Wellpath data to appear in the Survey Table in
the report.

Summary Options
Toggles to let you add additional tables into the report containing survey
header information and definitive wellpath data.

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Create a New Custom Report

The Survey Report Editor lets you design your own report format to
include required contents and survey table data.

The following graphic depicts the Survey Report Format Editor

Window:

Enter the name of the report. This name

will appear in the list of custom report
formats available to the user.

A comprehensive set of Report Items can

be included in the report the order
specified in this spreadsheet. Report
Items are available from a drop down
picklist.

Survey table contents spreadsheet. Build

you own custom survey tables by
selecting items from a drop down picklist.
Column labels and widths can be
customised by the user.

Name
Enter a name to identify your custom report.

Report Items to Display

You can include in your report several components including:

• Survey Report Header - survey name, tool name and start date
• Annotations - information assigned to this wellpath.
• Casings - a summary of casing points.
• Formations - a summary of formation details.
• Site Datums - a list of all defined datums within the site.
• Tool History - a summary of the survey tools used on this wellpath.
• Survey Table - a list of survey points. You must include the survey
table if you define items in the Survey Table Column.

Survey Table Columns

The survey observations and positions for each station.

Station - the row number in the survey listing.

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 Chapter 6: Survey Module

• MD - measured depth
• Inclination
• Azimuth
• TVD - True vertical depth
• N/S
• E/W
• Build - build rate
• Turn - turn rate
• Dogleg
• TFO - toolface orientation
• Vertical Section
• Closure Distance - horizontal distance from top of hole to each
survey point.
• Closure Angle - bearing from top o hole to each survey point.
• Map Northing
• Map Easting
• Lat Deg - latitude in degrees
• Lat Min - latitude in minutes
• Lat Sec - latitude in seconds
• Lat N/S - indicates whether north or south to the equator.
• Long Deg - longitude in degrees
• Long Min - longitude in minutes
• Long Sec - longitude in seconds
• Long E/W - indicates whether east or west of the Greenwich
meridian.
• Course Length - the change in measured depth from the last survey
point.
• Tool - survey tool assigned to this survey point.
• Vertical depth to System - adjusted to system datum (MSL/LAT).

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Redesign an Existing Survey Report

Survey Export
COMPASS can export a survey, a plan or a definitive path in any ASCII
format.

• Export Survey - The survey editor must be open for that survey to
be exported.
• Export Plan - The plan must be open in the plan editor.
• Export Definitive - No plan or survey open.

Export File Format

The export is in a standard character-separated-file based on the settings
below unless you choose one of the pre-defined file formats from the
list. If a format is selected it super-seeds all of the options chosen in the
dialog. Otherwise select User Selected to use the options below.

Complete Survey
Select this check box if you wish to export the interpolated plan back to
surface. Otherwise only the plan change points are exported. This does
not apply (invisible) if a survey is being exported.

The following graphic depicts the Survey / Plan Export Window:

Export survey/planned trajectory to

Data can be exported to any a text file or to the Windows
file forma available from a Clipboard. Clipboard option is the
picklist. Format files may be simplest technique to export the
constructed by clients. survey to WELLPLAN.
Select export units for Depth,
Inclination and Azimuths.

Actual survey stations can be

exported or an interpolated
Data exported can be limited to survey with a specified interval
a particular depth range
Include the final driller’s depth
(TD) at the end of the
interpolations.

Units
• Depth - Select feet or meters.
• Inclination - Select from the available list.

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 Chapter 6: Survey Module

• Azimuth - Select from the available list.

Column Delimiter
• Blank - Columns are left justified and separated one space.
• Tab - Column are left justified separated by a tab stop.
• User - Enter one character that is used to separate the columns.
The output can be directed to a file or to the Windows Clipboard for
pasting into a word processor, spreadsheet or the Windows Notepad.
When exporting to paste into Excel, you should set the delimiter to tab.

To export to a file (specify the filename in the file dialog).

To export to the windows clipboard for transfer to another windows

application.

Survey export using the formatted file:

COMPASS allows you to configure export file formats. The format files
(*.cef) are placed in the WELLPLAN\CONFIG directory, and when the
export dialog is called, a combo box containing the different formats
available is listed. The default format is called User Selected and takes
the settings for columns (MD-INC-AZI) with units and separator from
the dialogue.

Custom export formats can be used for a number of reasons:

• Quick export to spreadsheet of various data.

• Formats for Geological or Geophysical applications.
• Exports to other engineering applications.
• Preview of data in notepad, to cut and paste.
If requested Landmark can supply formats for a number of 3rd party
applications or can assist with the development of a new format
configuration files.

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 Chapter 7: Planning Module

Planning Module

Introduction
The Plan Editor is a mathematical toolbox consisting of a large number
of directional well planning solutions. Solutions are available for a wide
range of planning problems from simple 2 dimensional Slant and
S-shaped wells to complex 3 dimensional wells up to and beyond the
horizontal threaded through any number of targets. Easy to use links
with WELLPLAN for Windows enables directional well plans to be
quickly evaluated for engineering constraints.

Active plans can be combined with the Anti-collision module and the
Target Editor to provide a powerful decision making aid. The basic
components of the Plan Editor are:

• Plan Setup
• Planned Survey History
• Plan Editor Grid
• 2D and 3D Planning Methods
• Project Ahead
• Planned Walk Rates
• Wellpath Optimiser
• Planning Reports
• Plan Export

Plan Setup
When a New Plan is created, the Plan Setup window automatically
appears to allow the plan to be identified. Plan Setup is similar to Survey
Setup but includes Planned Survey Tool History and a Principal Plan
check box.

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The following graphic depicts the Plan Setup Window:

A plan can be given a Name and a Description, these will
appear on reports and wallplots. Additionally, the plan
name will appear in selection lists such as the browser

nly 1 plan in a wellpath can be Import planned

lagged as the Principal Plan trajectories constructed
hich can then form part or all of using other planning
he definitive wellpath software

lans must be Tied-On to define Define a Survey

starting point and orientation. Program so that
ie-on methods are: positional uncertainty
down the plan can be
User Defined - enter all used for anti-collision
parameters scans down the plan
From Wellhead - assume
slot location Lock the plan to prevent
From Survey - Tie plan MD other users from
along definitive wellpath or changing it
to a survey

Principal Plan
Each wellpath can have more than one plan. Indeed many plans can be
generated before the final profile is agreed upon. To identify the plan
you intend to drill you can mark one plan in a wellpath as being the
Principal Plan. This distinction is important as only the principal plan
can be included in the Definitive Path. This plan can also be used in anti-
collision analysis where survey data is not yet available.

Version
This field can be used to help keep track of various plans. It is not used
by COMPASS but appears in the Planning reports.

Tie-On Point
Similar to a survey, a Plan must have a defined tie-on point to act as the
starting point of the plan. Type in the starting point or get COMPASS to
interpolate the data for you. Note - if starting a sidetrack you should

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 Chapter 7: Planning Module

create a new wellpath first. There are three choices to specify the start
point as follows:

Start Point Description

User Type in the co-ordinates and depth of

the start point. This is attaching the
plan to a free point in space. No
checking is made on the validity of
the this tie-on point.

From Wellhead COMPASS starts the survey at the N/

S E/W co-ordinates of the well. You
can still specify inclination and
azimuth should the start point be non
vertical. Note - If in Company Setup
you set the local co-ordinate origin to
slot, the survey tie-on co-ordinates are
set to 0 N/S and 0 E/W and do not
inherit the well co-ordinates.

From Tie-point Ties on to the last point on the

definitive wellpath by default. You
can specify another measured depth to
interpolate from the current definitive
wellpath.

The start point (tie-line) items are as follows:

This start point... Means this...

MD The starting measured depth for the

plan.

Inc The starting inclination from vertical.

Vertical is zero degrees.

Az The starting direction from local

north.

TVD True vertical depth measured from the

selected Datum.

N/S North distance from the local co-

ordinate centre.

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Chapter 7: Planning Module

This start point... Means this...

E/W East distance from the local

co-ordinate centre.

Plan Import
Planned well trajectories can be imported from another source in the
same way as importing a Survey. The Plan Import Window behaves in
exactly the same way as Survey Import.

Between each Planned point, COMPASS generates a Landing

Calculator section. Though imported plans are difficult to re-plan, you
can change MD, Inc, and Azi. Inertial plans have Dogleg/Toolface –
Plan to a Point plan method assigned between each pair of points. The
important point is that plans generated using other directional well
planning software can be pulled into the COMPASS database that could
then be included for anti-collision scanning purposes.

Planned Survey Tool History

COMPASS enables a planned survey tool profile to be applied down the
plan. This enables the positional uncertainty of the planned trajectory to
be determined which could be used in anti-collision scans down the
planned path. This is very useful in that plans can be checked for any
collision problems before they are drilled.

If the Plan is saved as ‘Principal’ then this planned survey program may
be used to form the error surface of the definitive path when it is defined
by the plan.

A Survey enables a single survey tool error model to be assigned so

that positional uncertainty can be calculated over the depth range of the
survey. A Plan allows multiple survey tools to be assigned over
different depth ranges so that a more realistic survey tool error model
can be defined that would be comparable to the surveys recorded while
drilling.

The survey history editor is a grid where you must define the starting
depth that the tool would be used and the tool itself from the drop down
menu of Company survey tools. Extra rows can be inserted where
necessary using the keyboard Insert button or deleted using the
keyboard Delete button.

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The following graphic depicts the Plan Survey Tool History Window:

Measured depth range for different

survey tools can be defined down
the planned trajectory. Like other
spreadsheets in COMPASS, insert
and/or delete rows using keyboard
keys

Choose from the list of Company

survey tools using the drop down
menu

Plan Editor
The purpose of the plan editor is to generate a series of curve types to
form a planned wellpath trajectory to one or more target locations. The
Plan Editor has three areas - an interactive plan grid and a number of
plan method windows for data entry and calculation, and a toolbar. The
plan grid is always present and displays all plan sections and enables key
parameters of each row to be changed. The plan method windows are
used to define individual curves or profiles. The plan method windows
appear when you activate on of the method toggles.

COMPASS has over 20 planning methods. Some methods are divided

into subgroups accessed from the planning method icons. Each icon
reveals the input window for that method. The planning methods can be
divided into 2-dimensional tools, 3-dimensional tools and the Wellpath
Optimiser.

Each planning solution consists of sections displayed in the Plan Grid.

A section is a line in space with a constant dogleg, build or turn rate.
Different planning methods construct a different number of sections.
For example:

• Hold adds one section

• Slant Well adds 3 sections
• Thread Targets add multiple sections.
The Plan Editor is similar to the Survey Editor. Sections are added to the
grid using the different planning methods. Multiple planning methods
can be used when constructing a single plan. Like the Survey Editor, the
keyboard can be used to insert new sections at any point in the plan or
delete sections no longer required.

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Sections in the grid are mathematically linked together by the planning

method that was used to construct them. Therefore, deleting a particular
row in the grid results in all sections linked to that row being deleted as
well. You are advised of this before this occurs. To edit a section in the
plan, click on the relevant row in the grid and the plan method for that
row appears.

The following graphic depicts the Plan Editor Tabular Display:

on’t like what you last Plan Setup can be quickly Plans can be generated
hanged, click Undo or Redo accessed from the tool bar through more than one target

The plan grid is

interactive, white cells are
editable, change a value
and the plan re-calculates

Plan method toggles are

used to choose which plan
method is used. Different
methods can be combined
to form a wellpath through
multiple targets

When a Plan Method

toggle is activated, the
plan method window
displays the inputs
required to calculate Some plan methods have sub- When values have been entered for the
sections of that method method buttons plan method, hit the calculate button to
generate a trajectory

Plan Grid
The Plan Grid has changed extensively from earlier versions of
COMPASS. In 1998.7 the plan grid now supports direct modification of
plan parameters within the grid in addition to displaying sections
calculated using the traditional planning methods.

Each line in the grid displays the section end point in terms of MD,
Inclination, Azimuth, TVD, local Northing and Easting, Vertical
Section distance, Dogleg Severity, Toolface Orientation, Build rate,
Turn rate, Type and Target name if that section end hits a target. Type
indicates which planning method was used to construct that section. The
Plan Editor can be re-sized if necessary so that all values can be viewed.

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To Edit directly into the grid

Once plan section data has been calculated, you may edit the input
values directly into the grid. Alternatively, the last line in the grid may
be used to add plan sections directly. When adding lines to the end of the
plan, only certain combinations of parameters will work. At least 3
numbers must be entered (or 2 if DLS=0). This procedure also applies if
the has been used to insert a line in the middle of a plan.

The data combinations are in listed order below:

1. If Dogleg is defined as zero, then compute a straight line to one of

MD, TVD or VSec.

2. Inc, Azi and one of MD, TVD or Dogleg. (Inclination, Azimuth

projections)

3. Dogleg, Toolface and one of MD, INC, AZI or TVD.(Dogleg

Toolface projections)

4. N/S, E/W and TVD (constant curve to a point, VSec may be used
instead of N/S and E/W)

5. MD and 2 of the following Inc, Azi, Dogleg, Toolface.

Once three values have been calculated Click Enter to calculate when
you have finished entering data.

Note:

If you have made a mistake you can use the Undo/Redo

buttons to revert to the last known ‘good’ solution.

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Plan grid cells are directly editable. The last grid row can be used to add When a row/cell is selected, the plan
Change the value, tab out and the sections to the plan manually method used to generate that row is
plan is automatically recalculated. displayed beneath the grid

To Highlight Plan Sections in Views (plots):

Highlight a row in the Plan Grid, and when that plan is displayed in 3D,
section or plan view the corresponding plan section will be highlighted
in the plot.

Incremental Measured Depths

The planning algorithms remember incremental measured depths, rather
than absolute measured depths. What this means for instance is that a
plan to a target has a rathole of 300’, then the target was moved and the
plan angle changed, then the plan would keep the 300’ rathole even
though the final TD depth changes.

Targets
Before any directional well planning can take place, the planner must
have the location and geometry of any drilling and geological targets
defined within the Target Editor. These targets must be selected by the
current Wellpath before they can be used. Most of the planning methods
enable you to select a target to plan to. By default, the planning methods
design to the aiming point of the target though there is usually an Adjust
button available that allows you to manually set the aiming point around
the target. If a target is not defined, the well planner can usually enter
the location as a point in space: TVD, local Northing and Easting from
the Site centre.

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Plans that are designed to target locations remain linked to those targets.
If a target location is changed, all linked plans are updated
automatically. Therefore, the plan and target editors can be used
concurrently while directional well planning.

Plan Editor Tool Bar

The planning toolbar is located at the top of the Plan Editor. There are a
number of plan options from the toolbar:

• Save As and Save the plan. Save this plan by another name
• Undo and Redo the plan calculations – restore the last good plan
calculation.
• Plan Set-up – Edit the plan detail and tie-on information.
• Thread Targets – Construct a trajectory through several targets.
• Planned Walk Rates – Apply azimuth drift, where expected in
rotary drilling.
• Wellpath Optimiser – Take several planning options and
optimise for torque & drag.
• Projection to target – Quick calculation of vector to hit a target.

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Planning Methods

Plan method drop-down layouts are accessed by pressing the different

toggles. 2D planning methods within a vertical section include Slant and
S-Well design; 3D planning methods include Build/Turn curves for
rotary drilled sections, Dogleg/Toolface curves for steerable drilling
design, Optimum Align, Thread Targets and the Landing Calculator.
Additional planning methods are Hold to add a section with no build or
turn, Walk to apply predicted walk tendencies to hold sections in the
plan, and the Wellpath Optimiser that is used to optimise the wellpath
trajectory for mechanical constraints, lowest directional drilling costs or
least anti-collision risk. A Project To tool enables the bottom of the plan
to be projected to a target.

COMPASS has a number of planning methods suitable for different

types of directional drilling assemblies. All these tools construct
mathematical curves. When entering parameters for a planning method,
COMPASS always constructs a path if it is mathematically possible.
Sometimes this results in a peculiar wellbore trajectory (see below). A
drilling engineer should be capable of detecting these types of plans and
adjusting the plan parameters as necessary.

If an engineer enters parameters that result in a plan not being

mathematically possible, warning messages appear with a brief
description of the problem and an indication of what parameter requires
changing. For example, a low build rate parameter can result in the
wellpath not being able to build in the measured depth available to get
to a target location.

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The following graphic depicts an unexpected Wellpath Trajectory using

Positive Build Rate:

2D Directional Well Planning

The 2 dimensional well planning tools construct wellpath trajectories
that follow the plane of a vertical section. That is, there is no turn from
the slot to the final target. COMPASS provides two methods for
planning 2D wells: Slant well and S-Well. A slant well is a simple Hold-
Build-Hold profile whereas an S-Well can be a Build–Hold–Drop-Hold
profile or a Build-Hold-Build-Hold profile.

Slant Well Design

The following graphic depicts 2D Slant Well Design Parameters:

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To design a Slant well:

1 Type in the coordinates of the point to aim for or select a target.

2 Tick 2 of the unknowns from the list of 4 below. Example
unknowns are 2nd hold length and Maximum Angle.
3 Enter the two known parameters:
• 1st Hold Len - Length of initial hold section before the kick-off
point or more simply the kick off depth. Enter zero if you wish
no kick-off length.
• 1st Build - The build-up rate.
• Maximum Angle Held - The tangent angle of the profile.
• 2nd Hold Length - The length of the tangent hold section.
4 When ready to calculate press to compute.

Like all Planning methods, the entry parameter values can be changed
or the parameters ticked can be changed and other parameter types
defined and the plan re-calculated as many times as necessary without
having to exit from the drop-down window.

S-Well Design
An "S" well has three sections - Build - Hold - Build/Drop and is defined
by seven parameters. You can also add a hold for the kick-off

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The following graphic depicts 2D S-Well Design Parameters:

To enter a 2D -’ S’ well profile:

1 Type in the coordinates of the point to aim for or select a target.

2 Tick 2 of the unknowns from the list of 7 below. Example
unknowns are 2nd hold length and Maximum Angle.
3 Enter the five remaining parameters:
• 1st Hold Length - Length of initial hold section before the kick-
off. Enter zero if you wish no length before the kick-off.
• 1st Build Rate - The build-up rate.
• Maximum Angle Held - The intermediate tangent angle of the
profile.
• 2nd Hold Length - The length of the intermediate tangent
section.
• 2nd Build Rate - The second build or drop rate (+’ve or –‘ve).
• Final Inclination - The inclination you want to achieve at the
target.

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• Final hold length - The distance from the end of the last build to
the target. Enter zero if you wish no straight section before the
target.

The following graphic depicts an S-Well Plan Example:

The example above displays a planned S-Well planned to target T9 with

the Kick off Point at 1500ft, initial build rate of 2º/100ft, second drop
rate of 3 º/100ft to a final inclination of 10º with a final hold length to
the target of 1450 ft. With these input parameters, the calculated
inclination of the tangent section is 62.86 º with an interim hold length
of 3298.7ft. The calculated plan is shown above in 3D (left) and Vertical
Section (right) with each planned section highlighted with boundary
lines.

3D Well Planning
3D planning methods assume that the well is drilled under some form of
directional control where the well can be turned to a given azimuth from
a particular measured depth.

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Build/Turn Curves
The mathematics of Build & Turn curves assumes that the wellpath is
wrapped around the surface of a cylinder. The shape of the wellpath is
resolved into two planes, vertical (inclination) and horizontal
(direction). The build rate is the rate of change of inclination and turn
rate is the rate of change of direction or doglegs in the vertical and
horizontal planes respectively.

Build and Turn curves are constructed assuming that the sections are
drilled using a Rotary drilling assembly. A number of sub-methods are
available to plans different types of Build-Turn curves utilizing different
types of available information during the design.

The following graphic depicts the Build / Turn Curves Planning Models:

Build-Turn sub-methods are selected by pressing the appropriate icon at

the bottom of the plan method window. Selecting different icons results
in different parameter fields being active and inactive. Active fields
require a value for the sub-method to work. Inactive fields are calculated
using the entered parameters.

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The following graphic depicts a Build-Turn Drop Down Layout:

Required fields are Build-Turn sub-method icons. These activate the Some B/T Methods enable a target
active. Calculated required parameter entry fields when pressed. TVD or location to be selected. If a
fields are greyed out. target is selected, the Target Adjust
feature is also available.

Eight different sub-methods are available:

Click... To...

Build & Turn to Measured Depth—Apply a build and turn

rate until the specified measured depth. COMPASS
calculates the final location (TVD, N, E), inclination and
azimuth.

Build & Turn to True Vertical Depth—Apply a build and

turn rate until the specified true vertical depth. You can
specify a TVD or select a target to define the TVD.
COMPASS calculates the final measured depth, northing,
easting, inclination and azimuth.

Build & Turn to Inclination—Apply a build and turn rate

until the wellpath reaches a certain inclination. COMPASS
calculates the final location, measured depth and azimuth.

Build & Turn to Azimuth—Apply a build and turn rate

until the wellpath reaches a certain direction. COMPASS
calculates the final location, measured depth and
inclination.

Tangent to Point—Enter build and turn rates and

COMPASS adds three sections. It applies the build and turn
rates until pointed to either the correct direction or
inclination, whichever can be achieved first. The second
section is either a build or a turn to complete the projection.
If pointed to the correct inclination, then a turn is applied to
reach the required direction. If pointed to the correct
direction, then a build or drop is applied to reach the
required inclination. The wellpath is now pointing at the
target so the third section is a hold to target.

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Click... To...

Plan to Point—Enter a point or select a target to aim for.

COMPASS computes the build rate and turn rate required
to hit the target in one curve.

Online by TVD—Enter a point or select a target to aim for.

Specify the depth (True Vertical Depth) by which you want
to be online to hit the target. COMPASS adds two sections,
a build turn section to get the wellpath online by the TVD
then a hold section to the target.

Align by Inclination—Enter a point or select a target to aim

for. Enter the inclination you require and the build and turn
rates of the curve. At the end of the curve the wellpath
direction is aligned with the target and at your required
inclination.

Dogleg/Toolface Curves
The mathematics of Dogleg / Toolface curves assumes that the wellpath
is wrapped around the surface of a sphere - a circular curve with
orientation defined by toolface and radius defined by dogleg. Toolface
is the direction from high-side of the hole. Toolface is 0º at high-side and
180º at low-side. Looking down the wellbore, toolface is positive
clockwise and negative anti-clockwise. If the wellbore has no
inclination, toolface is referenced to local north.

Dogleg-Toolface curves are constructed assuming that the sections are

drilled using a Steerable drilling assembly. A number of sub-methods
are available to plans different types of Dogleg-Toolface curves
utilizing different types of available information during the design.

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The following graphic depicts the Dogleg-Toolface Curve Sub-

methods:

The same as Build-Turn curves, Dogleg-Toolface curve sub-methods

are selected by pressing the appropriate icon at the bottom of the drop
down layout.

The following graphic depicts the Dogleg-Toolface Drop Down Layout:

Depending on what sub-method is selected, After Calculating, the greyed out
the appropriate parameter fields are activated fields display their calculated values

The Dogleg-Toolface sub-methods are the Plan to tangent to a point generates 2

same as Build-Turn curves; except the sections: either Hold-Curve or Curve-Hold
calculated wellpath shape is different

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Eight different sub-methods are available:

Click... To...

Apply Dogleg / Toolface to Measured Depth—Apply a

Dogleg on an initial toolface angle until the specified
measured depth has been reached. COMPASS calculates
the final TVD, inclination, azimuth, northing and easting.

Apply Dogleg / Toolface to True Vertical Depth—Apply a

Dogleg on an initial toolface until the specified TVD has
been reached. You can specify a TVD or select a target to
define the TVD. COMPASS calculates the final measured
depth, inclination, azimuth, northing and easting.

Apply Dogleg / Toolface to Inclination—Apply a Dogleg

on an initial toolface until the wellpath achieves a certain
inclination. COMPASS calculates the final measured depth,
TVD, azimuth, northing and easting.

Apply Dogleg / Toolface to Azimuth—Apply a Dogleg on

an initial toolface until the wellpath reaches a certain
direction from local north. COMPASS calculates the final
measured depth, TVD, inclination, northing and easting.

Tangent to Point—You enter a Dogleg and COMPASS adds

two sections. It computes the initial toolface of the dogleg
section and the length of hold required to hit a target or user
defined point. If you want the dogleg section before the
hold click Curve-Hold or Hold-Curve for the reverse. The
length of the Hold section is dependent on the dogleg
entered.

Plan to Point—Enter a point or select a target to aim for.

COMPASS computes the radius of the dogleg and initial
toolface to hit the target in one curve. This type of plan
could be expensive in directional drilling costs. However,
the method is very useful as it calculates the minimum
dogleg required to steer between two points. COMPASS
calculates the final MD, TVD, inclination and azimuth of
the wellpath.

Online by TVD—Enter a point or select a target to aim for.

Specify the depth (True Vertical Depth) by which you want
to be online to hit the target. COMPASS adds two sections,
a curve to get you online by the TVD then a hold section to
the target.

Align by Inclination—Enter a point or select a target to aim

for. Enter the inclination you require and the Dogleg of the
curve. At the end of the curve the wellpath direction is
aligned with the target and at your required inclination.

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The following graphic depicts a Dogleg-Toolface Plan Example:

Slant Well design to target T8

Dogleg-Toolface curve-hold
design from target T8 to T9

Steer from T8 with 1.0° dogleg to

line up on T9

Hold to hit T9

The above example displays Dogleg-Toolface planned sections from

target T8 to T9. The entire plan consists of an S-well design to T8
followed by the Dogleg-Toolface curves. Looking at the Dogleg-
Toolface Drop-Down layout, the plan was constructed using the Plan to
Tangent a Point sub-method with a dogleg of 1º/100ft defined to target
T9 selected from the drop-down menu. The two sections are ordered
Curve then Hold.

Build-Turn v. Dogleg-Toolface
As discussed in the last two plan method sections, Build-Turn and
Dogleg-Toolface plan profile have a significantly different geometry.

Build-Turn plans approximate to Radius of Curvature curves that follow

the surface of a cylinder. These curves emulate rotary drilling where
build and walk are predicted. Build-Turn can also design a ‘flat turn’
where the inclination remains constant for example when sidetracking
to a different azimuth.

Dogleg-Toolface plans construct a Minimum Curvature geometry that

follows a ‘great circle route’ around the surface of a spheroid. Dogleg-
Toolface curves cannot be used to design a flat turn; the inclination
changes through the turn. For short turns, dogleg and toolface
orientation remain constant. For larger turns, Dogleg-Toolface curves
cannot construct a path with constant dogleg and toolface orientation,

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over the turn you’ll find that they change. This effect can be
considerable over a long distance.

Optimum Align
The Optimum Align planning method adds three sections: Curve, Hold
& Curve (also called Steer – Hold - Steer). You can specify a final
inclination and direction for the end of the final curve or if you select
two targets, COMPASS computes the inclination and direction between
them for you. If you select a single target, COMPASS lines up on the
target to plan the well down dip.

The following graphic depicts Optimum Align Planning Methods:

To build an Optimum Align profile:

1 Set restrictions on the curve shape in one of three ways:

• Doglegs—Specify the Doglegs of both curves.
• TVDs—Enter the start and end TVD of the intermediate hold
section (or TVD at end of 1st turn, TVD at start of 2nd turn).

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• Tangent Length—Enter the length of the intermediate hold

section, COMPASS calculates the TVDs and Inc/Azi.
2 Select the 1st Target to land the wellpath. You can adjust the
landing point vertically/laterally using the Target Adjust tool. You
can add a short section before the first target by specifying Hold
length with or without a build rate before hitting the 1st Target.
3 Determine the final inclination and azimuth using one of the
following 2 methods:
• Selecting a 2nd target to follow on to:
• Pick a target. The target you want to hit.
• Line up on target. The target you want the wellpath to line up on
at the end of the second curve. This target is remembered in the
plan and a hold is computed between the two targets.
• Defining the End Vector at the target:
• Pick No Target (Freehand). If Target 1 has a dip and strike,
COMPASS assumes you want to plan down dip and calculates
Inclination and Azimuth accordingly. These are defaults that
can be changed.
• Inc - Enter the final inclination required.
• Azi - Enter the final required direction.

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The following graphic depicts an Optimum Align Plan Example:

Kick Off Point

1st Curve section from Kick Off Point to start of

Tangent section, DLS = 2.5 deg/100ft

Tangent section from end of first turn to start of

2nd turn

2nd Curve section from Tangent section to

target T8, DLS = 3.0deg/100ft

Plan to hit target T8 with wellpath orientation

aligned with target T9.

T9

Simple hold section to hit 2nd target T9

The example above displays an Optimum Align plan to target T8

defined using two Doglegs. When the plan hits target T8, the wellpath
trajectory lines up to point directly at T9 so the well can be held to hit
T9. This type of method is very effective to plan a well with the
directional drilling completed top hole to limit costs. Deeper in the well
after hitting T8, the well can be drilled with a stiff assembly and held to
the final TD.

You can enter a short section before the first target by specifying Exit
length and build rate on the tangent length line.

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Hold Tool
The HOLD tool is a very useful utility for defining planned kick off points
or extending the trajectory beyond a target.

You can add a straight line projection to either a MD, TVD or VSec:

Select... To...

MD Enter the measured depth to project to. If the MD is

less than current MD of the plan, COMPASS
assumes you wish to apply an additional MD. For
example if your plan is at 5410 ft MD and you say
you want to hold to 90ft, COMPASS adds 90ft to
the plan giving a final MD of 5500 ft. If you typed
in 6000ft, COMPASS adds a hold of 590 ft to the
plan.

TVD You can specify the vertical depth of a target by

picking a target or enter a TVD

VSEC You can specify the vertical section distance by

selecting a target or entering a distance

Incremental Measured Depths

The planning algorithms remember incremental measured depths, rather
than absolute measured depths. What this means for instance is that a
plan to a target has a rathole of 300’, then the target was moved and the
plan angle changed, then the plan would keep the 300’ rathole even
though the final TD depth changes.

Thread Targets
Thread targets plans curved profiles through a series of targets with a
number of plan methods available between each pair of targets. The tool
is very useful to quickly generate rough plans through a number of
targets to see what magnitude of doglegs are required to plan through
them. It is also commonly used to plan wells up-dip using decreasing
TVD targets.

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The following graphic depicts the Thread Targets Planning Options:

For each one of the Planning methods, the Thread Targets tool also
enables the user to select how the targets are sorted. The options are by
increased displacement from the slot origin, descending TVD ascending
TVD or by Name. The last option enables targets to be sorted in any
order using the order that the targets were placed in the thread list.

The following graphic displays the Target Threading sort methods:

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The Thread Target window enables you to select which targets you want
to thread. The targets displayed are those selected by the current
wellpath.
Target Sort Methods

Target Thread Methods: COMPASS tries to use this dogleg if possible,

otherwise it is incremented automatically until a
• Curve Only solution is achieved through all targets
• Curve-Hold
• Optimum Align
• Straight
• Least Turn

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To thread targets:

1 Select a number of targets to thread by picking from the Add To

List button, (or double-click on them), you can remove them using
the Remove From list button.
2 Select the order in which the targets are to be threaded by choosing
from Sort Targets:

Choose... To...

Displacement Hit the targets in order of increasing horizontal

displacement.

Descending First hit the shallowest target then the next deepest and
so on.

Ascending Hit the deepest target first then the second deepest etc.

Name Hits the targets in the order specified in the thread

target list.

3 Select the threading method from the list:

Choose... To...

Curve Only Add on one curve section per target. COMPASS

computes the dogleg severity required to hit the next
target with one circular curve.

Curve Hold Adds two sections per target. Specify the Dogleg
Severity and COMPASS computes the initial toolface
angle and length of hold section required to hit each
target in turn.

Optimum Align Adds three sections per target a curve, hold and curve
and connects the last two targets via a straight line. See
Optimum Align planning method. You need to specify
the dogleg severity to make the turns.

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Choose... To...

Straight Line Finds the best straight line to thread through the targets.
It uses optimum align to get to the first target. Normally
the line starts and ends with the vertical depth of the first
and last target, but if the targets are near horizontal or
’sort by displacement’ is chosen, then the line is limited
by displacement. The best-fit line is weighted to hit
targets with smaller dimensions. The best-fit line does
not necessarily pass through each of the target
dimensions, a message is reported if a target has been
missed.

Least Turn Calculates a trajectory with the least amount of turn

through the targets

4 Specify the Dogleg to apply - Enter the Dogleg you require for the
selected curve type (does not apply to curve only). If the dogleg
severity is insufficient, then a better dogleg is suggested and the
path computed. If you’re not sure what dogleg to use, then leave the
value set to a very small value (e.g. 0.1º/100ft) and COMPASS
works out the doglegs. Note: if 0º/100ft is specified COMPASS
often defaults to 5º/100ft dogleg between each target. If this is the
case, try decreasing the dogleg and re-calculating to see if this is
indeed the minimum dogleg that can be used.

After generating a plan using this method, each set of plan sections
between targets is linked to a particular planning method – not the
Thread target planning method itself. For example the Thread Targets
solution can consist of Optimum Align sections and Dogleg-Toolface
curves. After pressing OK in Thread Targets, double-clicking on any of
the constructed sections would not fire up the Thread target drop down
layout, but the planning method drop down linked to that section itself.

Landing Calculator
The Landing Calculator is one of the more versatile but less commonly
used planning methods. It contains some methods for planning to
horizontal or dipping formation targets as well as general 3D curve

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methods. There are two types of Landing calculations: projection or

target plane.

Simple Projection
This computes the trajectory to land at a vector at a specified TVD, MD
or Dogleg.

1 Enter the required Inclination and Azimuth

2 Enter MD and compute the Dogleg required and TVD reached or
• enter TVD and compute the Dogleg and final MD or
• enter the Dogleg and compute the final MD and TVD reached.
• The other parameter in the Dogleg Toolface curve will be
calculated.

Target Plane
This lets you compute a wellpath to land on a plane defined by an
inclined target. This tool does not necessarily plan to the target itself
unless it happens to be a large one. The plane is defined in terms of Dip
and Direction that are assigned to targets in the Target Editor.

• Dip - the angle the plane makes with horizontal, positive down.
• Direction - the down dip direction.
• Azi - You need not land along the line of the dip. You can specify
the final wellpath direction.
For example, let’s say we have a target with dip 5º along direction 20º.

If the final wellpath direction is:

• 20º the wellpath is at 85º inclination and pointing down dip.

• 110º the wellpath is at 90º inclination at right angles to the dip.
• 200º the wellpath is at 95º inclination pointing up dip.

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Project To
COMPASS displays the Inclination & Azimuth, the Build & Turn and
the Dogleg & Initial Toolface required to get the wellpath from current
bottom hole location to a selected target. The results are for information
only and are not added to the plan. The projected section is not displayed
on any of the live graphs or in the reports.

1 Select the target to project to, or enter co-ordinates in the TVD, NE

and EW fields.
2 Hit the calculate button, and it will show the following results.
• Direct Projection: The inclination and azimuth are from the
plan end point to the target.
• Curve Projection: The vector and rates required to hit the target
in one continuous curve.

Tie Vector:
Once a direction projection vector has been calculated, you can copy
this vector to the plan tie-line. This method should be used to determine
the slant angle and direction for drilling with a slant rig.

Note: The tie-vector facility is not available when using Well Reference
Point vertical system.

Applied Walk Rates

With non-controllable rotary BHAs and rock bits, there is a tendency for
the hole azimuth to drift to the right (and sometimes the left), this is
known as ‘walk’. After a few wells have been drilled in the area you
should know roughly how much correction or lead azimuth to apply to
hit the target. Different amounts of walk are associated with different
formations, which can be defined by vertical depth.

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If the wellpath is properly led, steering should not be required as the

natural walk tendency brings the wellpath into the target. If walk is not
included the design, that is, if the wellpath is planned as tangent sections
between targets, frequent steering could result as the well is corrected to
counteract the natural walk tendency.

Enter the TVD of the start of a

known walk section. This may
correspond to a formation top,
change in lithology, or entry into
a geological structure.

To apply walk rates to a plan with straight sections defined:

1 Using one of the 2D planning tools to Slant or S-Well plan to one

target that has been created in the target editor.
2 Click in the toolbar and enter a number of walk rates in the
grid and the TVD’s where you anticipate the drift begins. Note that
a positive walk is to the right, negative walk is to the left.
3 Click OK or press ENTER to apply the walk rates. COMPASS
modifies the well plan by adding new sections at walk horizons and
uses the first target in the plan as the walk target. It only applies
walk to straight sections. Should you modify a walked plan using
another planning method you won’t be able to restore the original
unwalked plan.

Wellpath Optimiser
The Wellpath Optimiser is designed to help you optimize the wellpath
geometry for mechanical conditions. It contains the means to cycle
various plan constraints and then run the trajectory through torque-drag
analysis. Each result is examined for the maximum torque, tension,
buckling, side force and fatigue condition relative to the pipe limit for
this condition. The optimum solution can be based on your preference
or optimized to be the lowest stress condition meeting all of the criteria.
The mechanical results can be reported, graphed or the trajectory fed
back into the current plan for anti-collision. The optimiser works on

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Chapter 7: Planning Module

most common plan types, though it is most useful for plans that have
dogleg/build rates and kick-off or hold sections. You can also choose to
vary drill string or BHA type and length.

Here are the plan methods that are supported:

• Kick-off depths, by tie-on depth or hold section.

• Slant Wells and S-Wells, where dogleg is specified.
• 3D Curve Hold (DT or BT) and Optimum align (by doglegs).
• Straight sections at end of the plan or final projections.
Other plan methods can be in the plan but their chosen parameters are
not changed.

The first occurrence of the plan type is the one that is manipulated. For
example if a thread target method is chosen to multiple targets, then it is
the first Optimum-Align or Curve-Hold that is changed and the others
are not varied but recalculated.

The grid is used to display one or a number of possible solutions when

you click calculate. The grid is not available for edit though there are a
number of actions available through the grid. Selecting a line loads the
parameters from that line into the plan, analyses it and updates the plan
and views. Pressing the top label button of a number column sorts the
list showing the minimum first of this parameter. Pressing the top label
button of an error column (ER or Error Message) removes those lines
with errors from the list. It helps to do this before sorting.

Torque and Drag Calculations

The Torque Drag calculations used in this simulation are standard 'soft
string' and have been optimized for speed. They are run at the sample
interval used for the plan survey, this is +/- 100' or shorter for more
severe doglegs. It is an approximation of the model used for
WELLPLAN for Windows and should not be used as a substitute where
more accurate results are required. There are a number of differences:

• Tortuosity is introduced directly into the side force calculation

rather than changing the survey.
• Sinusoidal Buckling is computed using joint diameter for hole
clearance.
• Friction is split into radial (torque) and along hole (sliding)
components.

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• Analysis includes overpull to determine maximum for stuck/jarring

loads.
The numbers for the torque, tension, fatigue and buckle mean the
following:

Value = Tubular Load Limit / Actual Max Load.

So if a column is selected, then the maximum value is listed at the top,

which is, in fact, best limit/load ratio. It reports the maximum value for
the load in the whole string for each of the four load cases. So numbers
greater than one mean the limit has not been reached by any actual load.

It is a bit like casing design safety factors. The following values could
be used for the numbers:

• Tension = Pipe tensile yield / Actual max tension

• Torque = Pipe joint make-up torque / Actual max torque
• Buckling = Pipe Critical Buckling Force/Actual Max pipe
compressive axial force
• Fatigue = Fatigue stress limit / Actual max bending stress 25000
psi for DP, 18000 for HWDP and 13000 for casing or collars. The
bending stress is compensated for tension

Load Cases
This simulation uses 5 load cases to generate ranges of forces on the drill
string.

• On bottom drilling / rotating using weight on bit and rotary torque.

The drilling case can include sliding friction when steering with a
motor.
• Off bottom rotating the drill string with no bit weight and no bit
torque.
• Pick-up (pulling out of hole) uses +ve drag forces only and no
torque.
• Slack-off (running into hole) uses -ve drag forces only and no
torque.

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• Overpull uses defined stuck-force plus +ve drag forces; It assumes

you are pulling pipe and encounter a resistance force at the bit (and
not rotating).
Note:

These do not model compound friction such as Top Drive

rotating while running pipe. If compound load analysis is
required to model actual pipe angular velocity, you
should use WELLPLAN Torque/Drag software instead.

Wellpath Optimiser Editor

The following graphic depicts the Wellpath Optimiser Editor:

Error Type column details reason behind plan row failure

Error column flags which plans fail Torque/ Torque/Drag ratios compare worst case string load against
Drag or Planning constraints string rating. Can order plans from best to worst.

Results Grid displays Torque/

Drag and Cost for different
calculated planned trajectories
within user entered planning
constraints, enables user to
compare results

A Single Plan trajectory can be

Optimised within the ranges of
entered constraints in terms of
Costs, Mechanical Limitations
or Anti-Collision constraints

Though no Torque/Drag report

is available, all results for a
particular plan are available in
Tabs enable user to define precise or range of A Number of Plans can be calculated text format
values for different types of planning parameters for each one of the ranged
parameters. Results for all plans are
then displayed in the results grid.

To start the Wellpath Optimiser a plan must be open. There is an

associated Wellpath Optimiser View that shows the torque-drag and
side force charts for the current plan. Closing the plan gets rid of them
all, closing the optimiser closes itself and the optimiser view only.

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Plan Editor Interaction

You can return to the plan editor and manipulate the plan when the
wellpath optimiser is alive. Once the plan changes the optimiser re-
calculates torque-drag and updates the graphs and gives an error
message if a mechanical constraint is exceeded.

Data Context
The Optimiser data is saved in a file with the well so all optimizations
on the well uses the same data. The file is called W*.WOP where * is
the well number and it is stored in the WELLPLAN\OUTPUT directory.

The Tabs
There are 10 tabs, containing a number of entry fields. Some tabs have
1 or 2 Use Range check boxes indicating a parameter that can be cycled
or optimized. Depending on the plan methods used, some of the options
may not become available. Parameters that can be varied have a
minimum, maximum and step field. The minimum field contains the
default value for this parameter if is not to be cycled, and is the
minimum value for the cycling range when the check box is set.

Kick-Off Tab
Contains the Kick-off depth and the Final Hold length entry fields.

Kick-off Depth, Min, Max and Step

The Kick-off depth option is available if the plan contains a straight
section either alone or as part of a Slant or S-Shaped well. If the plan
is tied-on by interpolating a side-track depth, this depth can be
cycled through various tie-on depths. Kick-off depth is always an
interesting parameter to optimize because commonly there is a
median value that is best, though sometimes 2 solutions are
possible.

Final Hold Length, Min, Max and Step

Final Hold Length is used to get an idea of how far a tangent or
horizontal well can be drilled before running into limits. It is better

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not optimized because the solution always indicates the shortest

length. Final hold becomes available if there is some MD or TVD
projection beyond the last target. MD projection lengths are
expressed in distance from the last point whereas TVD is absolute.

Doglegs Tab

First Dogleg Severity, Min, Max and Step

The Dogleg Severity of the first build/turn section applies to all
multi-line methods to target where a dogleg is specified. The first
build inevitably optimizes to the lowest possible value.

Second Dogleg Severity, Min, Max and Step

The Dogleg Severity of the second build/turn section applies only
to S-Shape and Optimum Align methods to target where a dogleg is
specified.

Angles Tab

Tangent Angle, Min, Max and Step

The Tangent Angle of the 2D wellplan can be used given it is an
entry parameter in the Slant or S-Well shape.

Final Hold Angle, Min, Max and Step

The Final Hold Angle of the 2D wellplan can be used given that it
is an entry parameter in the Slant or S-Well shape.

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Location Tab

Surface Location East/North, Min, Max and Step

Surface Location can be optimized where the plan has tie-in from
wellhead. One or both local North and East co-ordinates can be
cycled to the optimum solution. This should apply only to wells
where there is some flexibility over surface location.

Note:

Selecting a plan from this option changes the plan’s start

co-ordinates to be different from the wellhead. If you
wish to accept this new location then load this point into
the site or well position.

Drill String Tab

In the drill string tab, you can enter 3 sections to comprise the Bottom
Hole Assembly:

• Drill Pipe
• Heavy Weight Drill Pipe
• Drill Collar Section
This tab only models a simple string that is acceptable in that it is used
to optimise the wellbore trajectory, not the string design. Thus, it is
useful to confirm that a given wellbore trajectory is drillable and
runnable and provides a basis for further drill string, casing string, or
liner string optimisation normally performed using Torque/Drag
software.

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Drill Pipe Section

The drill pipe tab contains a combo list of a number of common drill
pipe, casing, collar and HWDP sections. See the notes on the
Tubular Catalogue. The length of drill pipe is taken to be the TD
depth of the hole minus the HWDP length and the Collar length.

Heavy Weight Drill Pipe Section

The bottom hole assembly area contains a combo list of a number of
common drill pipe, casing, collar and HWDP sections.

Length of HWDP, Min, Max and Step

HWDP Length can be chosen as a variable, though generally the
optimum solution is the shortest BHA. This is the length of the
BHA, but not including the Collars.

Collar Type
Collar Type can be defined to be a section below the BHA of a fixed
length. There is no variation option on the Collar section.

Collar Length
Collar Length is the length of drill collars above the bit. Enter zero
for no collar section.

Open Hole Tab

The open hole and cased hole tabs allow the setting of some of the hole
section conditions.

Vertical Depth
This is the depth of the bit, if this is set to zero the bit is assumed to
be at the TD of the plan.

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Hole Diameter
This is the diameter of the bit.

Tortuosity
This is a measure of the roughness of the hole when drilled in terms
of dogleg severity. Example values for open hole are 0.25 for hole
drilled mainly rotating, and 1.0 for hole drilled while steering (in
degrees/100’ or 30m).

Friction Factor
This is the component of friction affecting the torque & drag results,
the value is unitless. Example values for oil based mud is 0.21 and
for water based mud is 0.29.

Wherever possible, friction factors should be obtained from

calibrated offset well data. If this is not possible, a well planner
should analyse a range of friction factors for a given fluid type to
anticipate the best and worst cases that may arise while drilling a
hole section. Analysing a range of friction factors provides
confidence to the well planner that all possible loads inherent in the
well trajectory are anticipated and designed for.

Cased Hole Tab

The cased hole tab allow the setting of conditions in cased hole.

Vertical Depth
This is the depth of the casing shoe, it’s location is interpolated from
the plan. If the casing depth is set to zero, then the open hole values
are taken to surface.

Hole Diameter
This is the inside diameter of the casing.

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Tortuosity
This is a measure of the roughness of the casing in terms of dogleg
severity. Example values for cased hole are 0.25 for smooth hole,
and 0.5 for rough hole (in deg/100’ or 30m).

Max Angle
Use the check box to define a maximum allowable hole angle in this
cased hole (allows for borehole stability or running of wireline tools

Friction
This is the component of friction affecting the torque & drag results,
the value is unitless. Example values for oil based mud is 0.17, for
water based mud is 0.24 and brine is 0.30.

Drilling Tab
Common drilling parameters for the simulations.

Weight on Bit
This is the weight applied at the bit to make drilling progress.

Torque on Bit
This is the assumed torque required to drive the bit and/or mud
motor.

The Bit Torque and WOB parameters define the loads acting on the
bottom of the string. These loads are used as the starting conditions
for the soft string Torque/Drag calculations.

Mud Weight
This is the mud density of the drilling fluid, assumed constant inside
and outside the pipe.

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Mud density is used to calculate the effective buoyed weight of the

tubulars that is used to calculate side force and therefore, torque and
drag calculation along a given string segment.

Overpull Weight
This is the allowable pulling tension at the bit used to trip jars or free
stuck pipe. The overpull load condition is usually the case for
maximum tension and includes the drag forces when pulling out of
hole.

Use Sliding Drilling

The sliding check box, changes the drilling load case to include
wellbore drag, otherwise the string is set to rotating and no string
drag is incurred. You may notice that buckling becomes much less
of a problem when the string is rotating.

Time+Cost Tab
These parameters are used in the time and cost estimates.

Operating Day Rate

The total cost per day for this drilling rig plus services.

Prod. Casing Cost

This is the cost of production casing for cased hole section in terms
of cost/length.

Liner Casing Cost

This is the cost of liner to complete the open hole section in terms of
cost/length.

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Rate of Penetration Table

Enter rates of penetration for rotating or steering for the vertical
depths to be encountered. This table is used to determine time costs
for drilling the directional plan.

TVD is the vertical depth down to which the ROP is operative.

• ROPR is the rotating rate of penetration used for all straight hole
sections.

• ROPS is the steering rate of penetration used when planned

angle change sections.

Rates of penetration are associated with formations and steering

becomes more difficult with depth.

Options Tab
Various options used in the analyses:

Anti-Collision
Check this option to configure the analysis to determine whether
plans collide with offset wells. Define an anti-collision boundary
area around the planned wellbores by entering a minimum range and
depth ratio in terms of x/1000. This computation is only possible if
you have open an anti-collision graph (ladder, travelling cylinder)
with the required offset wells. Note that having a large number of
offset wells slows down the Optimiser.

Tension Safety Factor

This is the allowance for torque or tension yield, for instance 1.25 is
80% of yield or over-torquing. A value less than 1 is not accepted.

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Side Force Limit

This is the threshold before it is assumed that tool joints cause casing
wear or keyseating. This constraint is optional by using the check
box.

Maximum number of trials

This is the maximum number of option combinations performed
when you click the Calculate button. This feature prevents the
Optimiser from spending a large amount of time computing several
thousand plans when you enter a wide range of combinations. If you
have a fast PC, you can set this value at up to 2000, although a value
of 100-500 is more common.

Buttons and other Features

Calculate
The Calculate button starts the simulations to cycle through each
variable in turn using the step size. Now if a number of variables have
been chosen (check boxes), then there can be large numbers of possible
solutions, so this option must be used with caution. There is a fixed limit
to the number of loops that can be set in the options tab, the default is
100.

If you have not checked any boxes, then Calculate runs one analysis,
taking the current settings from the minimum value. A single run
computes the plan geometry, interpolates a plan survey, and then runs
the torque-drag analysis.

Optimise Drag
The Optimise button fires off a number of cycles of analysis to hunt for
the best overall solution within the maxima and minima of all the chosen
variables. The method chosen takes 10 cycles in a binary search, each
cycle sets the max/min range of a variable to half the previous. Each
cycle looks at 2n samples where n is the number of variables (check
boxes set). However there are occasions where all of the extremes cause
a message Error no solution will satisfy!. This is caused by each of the
samples causing a simulation error either in the plan or a mechanical
limit being exceeded. In this case, reduce the limits of some of the
chosen variables. All optimization schemes require one permissible
starting case.

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Chapter 7: Planning Module

The optimum solution for each cycle is the one chosen from the set of
simulations to have the lowest worst case of the 4 mechanical limits.

Optimise Cost
Cost optimization operates with a similar algorithm to optimise drag but
the goal is to seek a solution that has the lowest cost or time. It does not
allow solutions that exceed mechanical limits. Cost elements taken into
consideration are the ROP table with the rig rate and the casing costs.
Generally time costs outweigh casing costs.

Optimise Anti-Collision
This procedure hunts for the well design that has the maximum distance/
depth ratio against any of the offset wellpaths. Check the anti-collision
in the options tab to configure the analysis to determine whether plans
collide with offset wells. This computation is only possible if you have
open an anti-collision graph (ladder, travelling cylinder) with the
required offset wells. Note that having a large number of offset wells
slows down the Optimiser.

Calculate or Optimise?
Consider the difference between the CALCULATE and the Optimise
buttons:

• The Calculate button runs every possible scenario within each

range that has been chosen, and lists them in the Grid. It then lets
you decide which result is best by clicking on the columns or
lines and looking into the Plan Editor or views. For instance, if
the following are chosen: a kick-off depth range of 1000 to 2000
at steps of 100 and a build rate range of 1 to 2 deg/100 at a step
of 0.1 then Calculate runs 11x11=121 simulations. There is a
default limit on the number of simulations in the Options tab, but
it can be increased.
• The Optimise button, on the other hand, calculates only the best
possible solution. Its optimum criteria is the minimum of the
four limit ratios (i.e. the load case closest to the limit). It then
chooses the solution that, through all the ranges defined, has the
maximum limit (in other words, is the least loaded string). The
optimized solution allows a user to scan more variables at one
time than the Calculate option.
Which you choose depends on how constrained the problem is. If the
sheet is completely clean, then the Optimiser is more useful. If the
drilling situation is fairly well defined, but can vary two or three options
(like KOP, DLS), then the Calculate option is adequate.

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An additional consideration would be that the optimized solution hunts

using any variable within the Min/Max range without the step value,
while the Calculate option uses the step sizes.

Notepad
Takes the current selected analysis and reports the torque/drag
results to Windows Notepad. This file is tab separated and can be
loaded into a spreadsheet for reporting. If no line is selected in the
results grid, then the contents of the grid are reported to the notepad.

The contents of the standard report are explained below.

• DEPTH - Measured depth of this point in the drill string

• PIPE# - Reference number of pipe section, (1=Collar, 2=BHA,

3=Pipe)

• HOLE# - Reference number of hole section, (1 = Cased, 2 =

Open hole)

• WBTRQ - Torque when drilling

• FHTRQ - Torque when rotating off bottom

• MAXTRQ - Make-up torque of pipe, used as limit

• WBWT - String weight/tension when drilling

• PUWT - Weight when picking-up

• SOWT - Weight when slacking-off

• FHWT - Free hanging weight (rotating off bottom)

• OPWT - Weight when pulling with overpull at the bit

• HELB - Helical Buckling limit

• WTMAX - Tension limit of tubular

• BSTR - Bending stress

• BMAX - Maximum bending stress (fatigue endurance limit)

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• SFOR - Lateral side force (+is up and - is down/lowside)

• SFMAX - Limit on side force for keyseating/casing wear

Grid Manipulations
The grid is used to display one or a number of possible solutions when
calculate is pressed. The grid is not available for edit though there are a
number of actions available through the grid.

• Selecting a line loads the parameters from that line into the plan,
analyses it and update the plan and views.
• Pressing the top label button of a number column sorts the list
showing the minimum first of this parameter.
• Pressing the top label button of an error column (ER or Error
Message) removes those lines with errors from the list. It helps to
do this before sorting.

Grid Columns
The grid columns contain salient parameters for each run of the
analysis.

This
Parameter... Indicates...

ER Whether this analysis was successful. It shows a cross if

an error or failure has happened.

Error Type The type of error (geometry) or limit condition that has
been exceeded.

KOP The Depth of the kick-off from vertical or side-track.

DLS1 The Dogleg Severity of the first build/turn.

DLS2 The Dogleg Severity of the second build/turn.

Time The time for directional drilling this well.

Cost The cost incremented in the directional phase of this well.

Torque Maximum ratio value of make-up torque/string torque for

the pipe in this analysis.

Tension Maximum ratio value of yield tension/string tension for

the pipe in this analysis.

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This
Parameter... Indicates...

Buckle Maximum ratio value of helical buckling limit/string

compression for the pipe in this analysis.

Fatigue Maximum ratio value of fatigue limit/bending stress for

the pipe in this analysis.(tension corrected).

Drill String The Drill Pipe name from the catalogue.

BHA Bottom hole assembly tubular type from the catalogue.

Drill String The Drill Pipe name from the catalogue.

BHA Bottom hole assembly tubular type from the catalogue.

Start NS Surface location North co-ordinate.

Start EW Surface location East co-ordinate.

BHA Length Bottom hole assembly length.

Hold Length Length of the final hold section in the plan.

Tangent The intermediate hold angle of the plan (2d plans).

Angle

Final Angle The angle of the plan at the target (2d plans).

Tubular Catalogue
The tubular catalogue used for the optimiser is called TUBES.CSV and
is located in the COMPASS\CONFIG directory. It can be loaded into a
spreadsheet and edited. The entries are grouped by type and listed within
each group in order of size, then yield strength. This order should be
maintained because the logic of the optimiser depends on it. The units
are API and not changeable. The file contains a number of columns as
follows:

• Name - used for the selection and reporting

• Pipe body outside diameter (in)
• Pipe body inside diameter (in)
• Tool Joint outside diameter (in)
• Pipe weight per length (actual) (lbf/ft)
• Tensile Yield strength (lbf)
• Make-up Torque (lbf.ft)

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• Fatigue Strength (psi)

• Pipe Joint Length (ft)
• Tubular Type (1-4) 1= Drill Pipe, 2=Drill Collar, 3=HWDP,
4=Casing
• Material Type (1-4) 1= Steel, 2= Aluminium, 3=BeCu,
4=Titanium)

Wellpath Optimiser Viewer

The following graphic depicts the Wellpath Optimiser Graphics for
extended Build-Hold-Build-Hold Sub-Horizontal Plan:

The wellpath optimiser graph is a plot of the torque, tension and side
forces on the currently selected plan. The Viewer appears when the
Wellpath Optimiser form is called from the Plan editor. It can be closed
without closing the editor. The viewer is intended to provided a visual
representation of how close the currently selected plan is approaching
any mechanical constraints such as contact force limit, API tensile yield,
or make up torque limit. This graph is not intended to be a replacement
for a full torque/drag analysis.

The Graphs
A view of torque drag results in graphical form is given when the
optimiser is open. It updates when any single analysis is run, or a line

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is selected from the grid. There are 3 graphs, each single graph can
be altered by clicking in its axis area.

Measured Depth against Torque

This graph has a number of lines:
• On-bottom torque (blue)

• Off-bottom torque (green)

• Make-Up Torque limit (red)

Measured Depth against Tension/Compression

The tension graph has a number of lines:
• On Bottom Drilling (blue)

• Off Bottom Rotating (green)

• Pick -up weight

• Slack-off weight

• Overpull weight (yellow)

• Helical Buckling limit in compression (red)

• Pipe yield limit in tension (red)

Vertical Depth against Vertical Section with Side Force

Commonly known as the hairy wellpath plot. This graph is good for
visualizing the points in the wellbore profile where there is
maximum contact force. The strike marks indicate the side force per
tool joint. Marks on the lowside of the wellpath indicate gravity
forces. Marks on the highside of the wellpath indicate tension in
dogleg forces.

This graph includes:

• The wellpath vertical section line (yellow)

• Side forces adjacent to the wellpath (blue)

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• Side force limit lines where requested (red)

• Wellpath labels every 1000' or 500m MD.

• A casing shoe marker to indicate the Last Casing depth.

The red side force limit lines can be turned on/off by choosing the
'use side force limit' in the Options tab of the Wellpath Optimiser.

Additional Plans
The additional plans selector is accessed from the Browser wellpath
plan list if a plan is currently open. The tool enables a number of
plans to be visually evaluated or compared on all open graphics. The
list box includes all plans contained in the current wellpath. To
include a plan on the lives graphs click on the toggle to the left of the
plan name.

Planning and Anti-Collision

The Anti-Collision module is designed to use the ‘active’ path as the
reference wellpath when performing an anti-collision scan against offset
wells. The active path defaults to the definitive wellpath if no survey or
plan is open. If a plan is open, the anti-collision module scans down the
plan. This is a very constructive feature in that plans can be designed to
adhere to a company’s anti-collision policy as defined within Company
Setup. Changes to a planned trajectory automatically results in all anti-
collision graphs or wallplots being updated automatically. Any reports
that are open would need to be regenerated.

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The following graphic depicts the 3D Proximity Graph with a planned

Sidetrack being scanned against an offset slant well:

The example above displays a planned sidetrack well scanning against

another wellpath in the same site. In this example there is a considerable
collision risk so this sidetrack trajectory has to be changed in order for
the plan to be approved prior to drilling.

Planning Reports
Having designed a wellpath trajectory, an engineer must be able to
communicate that trajectory to other colleagues across disciplines in
order for it to be assessed. COMPASS provides a number of methods to
accomplish this using Formatted Reports and ASCII file output with
predefined or user defined contents, hard copy output of the live graphs
or multi-sized wallplots, and user configurable export file formats.

In Planning Reports you can select a planning report or configure a

custom planning report that can be pre-formatted and displayed using
the WELLPLAN Report Manager or sent to an ASCII file to be used or
manipulated using other software such as Excel.

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Planning Reports is accessed from the Planning menu if a Plan is open

or from the main COMPASS toolbar .

The following graphic depicts the Planning Reports Window:

COMPASS offers two predefined planning reports.

• Planning Report (Local)

• Planning Report (Geographic)
In addition to the two standard reports, you can configure your own
report format using the New & Edit tools.

Planning and Survey reports that include targets show 2 lines for each
target. The 1st line is the target position, the 2nd line is where the survey/
plan intercepts the target depth (i.e. how much the target was missed by).

The (Local) Planning Report comprises:

• The plan change points or start points for each section:

• MD
• Incl
• Azi
• TVD
• N/S
• E/W
• DLS
• Build Rate
• Walk Rate
• TFO

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• Target
• A block report for each plan section with interpolated points.
• MD
• Incl
• Azim
• TVD
• N/S
• E/W
• VS Section
• DLS dogleg
• Build Rate
• Walk Rate
• TFO Toolface
• A complete report from start to end resembling the standard survey
report:
• MD
• Incl
• Azi
• TVD
• N/S
• E/W
• VS
• DLS
• Build Rate
• Walk Rate
• Tool Type
The (Geographic) Planning Report displays each interpolated plan point
converted to map and geographic coordinates. The conversion is based
on the geodetic parameters configured in Field Setup.

The report comprises parts 1 & 2 of the Local report plus part 3 in the
following format:

• MD
• TVD
• Incl
• Azi
• N/S
• E/W
• Northing
• Easting
• Latitude

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Chapter 7: Planning Module

• Longitude

Button Options

Click... To...

Store the report to disc as an ASCII file. You can load the
resulting ASCII file into Windows Notepad, word
processors such as Word for Windows or into a
spreadsheet.

Review the report prior to printing. This fires up the Report

Manager that enables you to Display, Print or Save the
formatted report.

Customize some of the contents of the report. You can

apply interpolations over some or all of the Plan, output to
any of the Site datums on TVD and/or MD, and add extra
points to the survey table.

Vertical Depth Reference

Vertical Datum - You can adjust the True Vertical Depth on your plan
report to any datum defined within the site. The <current datum> is the

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 Chapter 7: Planning Module

wellpath datum that is defined in Wellpath Setup. Different datum levels

can be defined in Site Datum.

Apply to Measured Depths - Select this if you want both the vertical
depths and measured depths to be displayed to the new datum elevation
for the report.

Interpolate
The plan can be interpolated at intervals of MD or TVD. Note that TVD
interpolations can be dangerous if the planned wellpath trajectory is near
horizontal. Note that the plan stations are already interpolated at
intervals a minimum of 100’ (30m). Stations are always included.

Interval - If you select interpolation you must specify the depth interval.

Range - Enter the start and end depth of the range to print.

Include
The following check items can be included in the plan report.

• Header - This block includes title information like Name, Data,

Version etc.
• Raw Plan Details - The Plan Section Information as shown in
Planning's Plan Editor.
• Survey Sections - The plan partitioned into sections and
interpolated at the specified interval.
• Complete Survey - The plan interpolated at the specified interval
and not partitioned by section boundaries.
Additionally the following items are added:

• As interpolated stations in the Complete Survey section of the plan

report, with the text in the tool/comment column. To print it you
must click the Complete Survey check box.
• As a summary block at the end of the report.
• Casings
• Formations
• Annotations
• Targets - Include a summary section with wellpath targets.

Create a New Custom Report

Custom reports lets you design your own report format.

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Chapter 7: Planning Module

The following graphic depicts the Custom Survey Reports Window:

The Custom Planning Reports Window is the same as Custom Survey

Reports except that the Sections list includes Plan Report Header Plan
Raw Section Details. The tool enables companies to standardize on their
own custom report formats that meet their particular reporting
requirements.

Redesign an Existing Custom Plan Report

You can edit and change the design of an existing report using the design
tools used to create new custom reports.

Delete Report Format

Report formats that are no longer required can be deleted to prevent
them from being used.

Planned Wellpath Export

Using the same mechanism as Survey Export, planned wellpath
trajectories can be output to text files, to the Windows clipboard or to

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 Chapter 7: Planning Module

any pre-defined export format. This enables plans to be incorporated

into other documents or other software packages that can analyse
wellpath trajectories within their environments; for example, reservoir
evaluation or seismic mapping packages.

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 Chapter 8: Anti-Collision Module

Anti-Collision Module

Introduction
The Anti-Collision module is the most critical functionality provided in
COMPASS that affects drilling safety and operator costs.

• Safety in terms of collision avoidance and drilling close rules.

• Cost in terms of the potential risk of a wellpath interfering with one
or more offset wells requiring decisions to be made on drilling or
production restrictions.
Results from the anti-collision module are used directly to make these
types of decisions.

Companies differ in their approach to anti-collision scanning; however,

COMPASS was designed to accommodate most commonly used
methods. Company anti-collision policy is usually set out in a corporate
drilling procedures manual. This may be your own company or a client.
COMPASS therefore sets anti-collision parameters at the Company
Setup level which is typically locked and therefore protected from day-
to-day users.

COMPASS enables you to perform an anti-collision scan down to any

open definitive wellpath, well plan, or survey, including project ahead
sections constructed from within the Survey Editor. The scan can be
conducted against any number of wellpaths within the same well, site,
or field. Additionally the scan can be applied against nearby wellpaths
located in other fields or companies. If used correctly, COMPASS is
capable of detecting a collision risk from a reference well, including all
offset well trajectories defined in the COMPASS database. Results are
available on a variety of plots and reports.

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Chapter 8: Anti-Collision Module

Concepts
The COMPASS anti-collision module is defined by 4 concepts:

This concept... Determines...

Error System How positional uncertainty is calculated

Scan Method How wellpath separation is calculated

Error Surface How separation factor is calculated

Warning Type What criteria is used to issue warnings

The Data Structure section of this manual described how the Company
Setup dialogue is used within COMPASS to apply company anti-
collision policies so that all anti-collision results are consistent within
the same rules and assumptions defined by the chosen models. It is very
important that companies recognise the importance of ensuring that
COMPASS data is distributed to all sites with exactly the same
Company setup and that it is generally kept locked to prevent the setups
being changed.

Error System
Prediction of wellpath location uncertainty is fundamental to safe and
cost-effective well design. Wellpath trajectory is only imperfectly
represented by survey measurement and trajectory calculations.
Because survey instruments are not 100% accurate, errors can occur in
calculated borehole trajectory. Uncertainty envelopes for wellpath
trajectory are calculated based on survey tool error models and provide
the minimum standoff distance to prevent wellbore collisions.
Uncertainty estimates range from field-based rules of thumb to strict
analytical and statistical methods.

In COMPASS there are four survey tool error models available to

calculate wellbore positional uncertainty:

• Systematic Ellipse (also known as Wolff & de Wardt)

• Cone of Error
• Inclination Cone of Error (note: This is only available in the Survey
Tool editor)
• ISCWSA

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 Chapter 8: Anti-Collision Module

Systematic Error Ellipse

This model is based on SPE paper 9223 by C.J.M. Wolff and J.P. de
Wardt first published in the Journal of Petroleum Technology in
December 1981. The model is a statistical treatment for the distribution
of errors caused by internal and external influences.

The main theme of the paper demonstrates that the major cause of errors
are systematic (they happen consistently in one vector direction) from
one survey reading to the next. There are random error sources, but they
are negligible and cancel out over a number of survey readings. The
mathematical methods applied by the paper are now industry standard,
but some of the example coefficient values and weighting factors are not
current with modern directional survey instruments. The mathematics
behind some of the calculations also do not work correctly for horizontal
wellbores. Additionally, to avoid confusion, Wolff & de Wardt chose to
not implement confidence levels which describes the repeatability of
survey readings. This implied that readings taken by survey tools using
this model were consistent to 2 standard deviations (95%).

The Systematic Ellipse error model has six coefficients:

Coefficient Definition

Misalignment Error An error in the instruments centralisation in

the borehole/casing.

Depth Error An error along the hole depth measurement

by wireline or pipe tally.

Inclination Error An error in the inclination measurement.

Reference Error An error in azimuth reference. Declination for

magnetic tools or foresight for gyroscopes.

Gyroscope Azimuth Error An error in gyroscopes azimuth caused by

gimbal drift. Exclusive of Magnetic Azimuth
Error.

Magnetic Azimuth Error An error in magnetic azimuth caused by the

drillstring. Exclusive of Gyroscopic Azimuth
Error.

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Chapter 8: Anti-Collision Module

Because these 6 error terms can have different magnitudes in any

direction, the shape of the 3D error surface at any point in the wellbore
is an ellipsoid, as illustrated in the following diagram:
Systematic Ellipse (Wolff & de Wardt) Error Terms
Combines the following Survey Tool errors:
Relative Depth Error
Error in measuring along hole depth e.g. stretch in
a wireline, drillstring measurement
Misalignment Error
Error due to instrument misalignment in the well-
bore due to poor centralisation, non-axial wireline
pull
True Inclination Error
Error in inclination reading in vertical plane
Compass Reference Error
A constant error in direction due misalignment e.g.
gyro foresight error or error in magnetic declina-
tion
Drillstring Magnetization
Magnetic interference cause by “hot spots” and
BHA component configurations
Gyrocompass
— Error due to gyro gimbal drift caused by
running procedures, Earth’s rotation, time,
temperature, inclination, and gyro moment of
inertia, and gimbal construction

Inclination Azimuth Error Grid

The systematic error model coefficients and their weighting factors
defined by Wolff and de Wardt are thought inadequate for modern
solid state magnetic instruments and for rate gyroscopes.
COMPASS provides the inclination/azimuth error grid to help refine
error models for more complex instruments. The inclination and
azimuth error characteristics for each inclination angle range can be
provided by the manufacturers and inserted into tables.

Cone of Error
This model assumes an error spheroid around each observation, that is
uncertainty is constant in all directions. The size of the spheroid is

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 Chapter 8: Anti-Collision Module

computed assuming a constant expansion of the surface for a given

along hole depth interval irrespective of direction.

The calculation is as follows:

Radius of sphere around previous observation + MD

interval x survey tool error coefficient / 1000.
The starting error around the wellbore at the well reference point
(mudline or ground level) is the well error plus the top borehole radius
(TBR), if it has been entered. The model is empirical and based on field
or test observation comparisons of bottom hole positions computed
from various instruments.

Inclination Cone of Error

Similar to Cone of Error, the Inclination Cone of Error model defines an
expansion rate of the error surface that is dependent on wellbore
inclination. That is, the survey tool error coefficient depends on the
current tool inclination and the values contained in the Inc/Error grid for
that survey tool.

Like the Cone of Error model, the resultant error surface at any point
along the wellpath is a spheroid, as displayed in the following graphic:
Inclination Cone of Error
Inclination Expansion
0° to 14.99° 7ft/1000ft
15° to 24.99° 9ft/1000ft
0 0ft
° 7 f t/1 0 25° to 34.99° 12ft/1000ft
.99 0 ft
o 14 00 35° to 49.99° 14ft/1000ft
Up t f t / 1 ft
. 9 99 0 00 50° to 79.99° 15ft/1000ft
24 t /1 80° to 89.99° 21ft/1000ft
° to 2f
15 1
9°
ft

.9
00

34
10

o
°t
ft /

/1000ft

80° to 89.99° 26ft/1000ft

25
14
9°
.9

15ft
49
o
°t

79.99°
35

50° to

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Chapter 8: Anti-Collision Module

ISCWSA
The ISCWSA committee’s remit was to “produce and maintain
standards for the Industry relating to wellbore survey accuracy”. A
number of companies supplied resources (Anadrill, BP, BGS, Gyrodata,
Halliburton IKU, INTEQ, Landmark, Norsk Hydro, Saga Scientific
drilling, Shell, Sperry Sun, Sysdrill, Statoil, Tensor) but the main
working group was formed by BP, INTEQ, Statoil and Sysdrill.

The committee recognised that directional drilling requirements have

moved on from the 1970’s when the Systematic Ellipse model was
constructed. Modern needs require smaller geological targets to be hit
often drilled in mature fields with a large number of nearby wellpaths.
The simplistic WdW model could not handle such strict requirements
and accurately model additional performance parameters measured
from vendor survey tools.
Industry Steering Committee for Wellbore Survey Accuracy
Dynamic Number of Error Sources (Terms), each
defined by:
•Name e.g. Accelerometer Bias
•Vector direction for error source
•Azimuth
•Depth
•Inclination
•Lateral
•Misalignment
•Inertial
•Bias
•Value error value for the source of error

•Tie-On determines how an error source is tied onto

sources:
•Random
•Systematic
•Well
•Global
Formula weighting for each error term e.g. ASX
 0 
1 
 − cos I sinτ 
(cos I sin A sinτ − cos A cosτ ) tan Θ + cot I cosτ 
G
 m m 

Range inclination range for error term

 L−1 Kl  K−1 
MK = ∑ ∑ ∑mi,l,k  + ∑mi,L,k + mi,L,K
svy

i  l=1 k=1  k=1 

L−1 K−1
,K = ∑Ci,l + ∑( ei,L,k ) .( ei,L,k ) +( ei,L,K) .( ei,L,K)
T T
Cirand rand

l=1 k=1
T
L−1  K−1   K−1 
Cisyst
,K = ∑Cisyst
,l +  ∑ei, L,k + ei, L,K . ∑ei , L,k + ei , L,K 
  
l =1  k =1   k =1 

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 Chapter 8: Anti-Collision Module

A number of other factors provided the incentive for an alternative

industry model to be developed:

• risk-based approaches to collision avoidance and target hitting

required positional uncertainty to be associated with confidence
levels, a term only implied with the WdW model
• changed relationships between operators directional drilling and
survey companies forced all parties to share information on tool
performance
• drilling and geoscience software enabled more sophisticated tool
error models to be incorporated with results that could be viewed
in 3D earth model visualisations
• survey program designs to hit smaller drillers targets dictated by
tool error models and smaller geological targets

As described in the Survey Tool Editor section of this manual, the

ISCWSA committee designed a dynamic survey instrument error model
specifically for solid state magnetic instruments (e.g. MWD & EMS).
The resultant model is described in a paper published by H.Williamson
“Accuracy Prediction for Directional MWD” by Hugh Williamson as
SPE56702. Essentially, the model enables an operator or survey
contractor to define a dynamic number of parameters or error terms
appropriate for a survey instrument.

Which Error Model to Use?

Different error models predict different error surface geometries with
depth. The error surface dimensions for any wellpath are determined
using entered error coefficients for a particular survey tool error model.
The model you use is dependent on the type of survey tool, how it is run,
and how it has been calibrated within QA/QC procedures defined by the
survey contractor and/or the operator. Those QA/QC procedures are
usually designed to guarantee that a survey tool is accurate to within the
error coefficients defined for that tool.

Wolff & de Wardt tool terms are available for most wellbore survey
instruments and have been for some time and therefore are still the most
commonly used error models. Progressive survey contractors and
operators are moving to ISCWSA tool terms as they enable survey tool
performance to be more appropriately modelled. Additionally ISCWSA
enables the limitations inherent in Systematic Elllipse to be avoided e.g.
90deg inclined wellbores. It is anticipated that ISCWSA will soon be the
predominant error model used within the industry. COMPASS has been
enhanced to help clients enable that transition.

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Chapter 8: Anti-Collision Module

Scan Method
The purpose of an anti-collision scan is to calculate the distance from the
scanning point on a reference well to the ‘closest’ point on an offset
well. This distance is known as the centre-to-centre distance or wellpath
separation. Different scan methods determine different separation
distances because each technique uses a different algorithm and may not
find the same closest point as another technique.

Four Scan Methods are available in COMPASS:

• 3D Closest Approach
• Travelling Cylinder
• Horizontal Plane
• High Side + Azimuth
In the following explanations the reference wellpath is the wellpath
being planned, drilled or surveyed. You check the distance from the
reference wellpath to any number of offset wellpaths. COMPASS scans
down the reference wellpath at intervals defined in the Interpolation
Interval and computes the distance to the offset wellpaths using one of
the following scan methods.

3D Closest Approach
At each MD interval on the reference wellpath, COMPASS computes
the distance to the closest point on the offset wellpath. At some scanning
depth on our reference wellpath, imagine an expanding spheroid. The
minimum separation occurs when the surface of the spheroid initially
touches the offset wellpath, separation is the radius of the spheroid.
Because the offset wellpath is now at a tangent to spheroid the line of
closest approach is perpendicular to our offset wellpath.

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The following graphics display the 3D Closest Approach Scan Method

(left) and the Travelling Cylinder method (right):
Offset Well Reference Well Offset Well Reference Well

3D

l
gona
Ortho

Travelling Cylinder
This scan method uses a plane perpendicular to the reference wellpath
and intercepting offset wellpaths as they cut through the plane. The
surface resembles a cylinder with the size of the maximum scan radius.
The travelling cylinders method computes distance from the offset
wellpath stations back to the reference wellpath. The benefit of this
method is that intercepts are detected even when the wellpaths are
approaching at a perpendicular. In this case, there may be more than one
point in the TC plane for the same depth on the reference.

Depths are interpolated on the offset wellpaths and resulting in irregular

depths on the reference wellpath. Therefore the 3D anticollision view
and travelling cylinders depth slice option are not possible with this
method, because they rely on regular depths on the reference.

High Side + Azimuth

High Side+Azimuth is a variation of the Travelling Cylinder scan
method. The separation calculation method is orthogonal, but toolface
orientation is high-side angle plus current wellpath direction. Toolface
angle to an offset well is then reported as the angle from the high-side of
your current wellpath + the azimuth of your current wellpath. This
method avoids confusion at low inclinations on a Travelling Cylinder
Plot when the reference wellpath passes through the vertical resulting in
a 180° shift in high-side orientation.

The confusion is caused by an apparent near-miss by plotting a

continuous line through adjoining scan stations that results in the line

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Chapter 8: Anti-Collision Module

crossing at or near the centre of the travelling cylinder graph as the well
crosses vertical. The high side + azimuth method thus stabilises the
bearing component when direction and high-side are uncertain at low
inclinations.

The following graphic displays a comparison of Travelling Cylinder and

High Side+Azimuth methods:

Elevation Plan
In this reference well, high side orientation
flips through 180 deg as the well passes
through vertical. The offset well is vertical
and to the south east.

Travelling Cylinder
Angle From
Travelling Cylinder scan
Distance High Side results plotted on a travelling
15 10° cylinder graph results in an
10 20° apparent collision (if the points
are joined together). A line
5 40° crosses the centre of the
5 220° graph where the reference
10 200 well passed through vertical
15 190°

High Side Angle + Current Well Azimuth The High Side + Azimuth
method correctly portrays this
situation by showing that the
A n g le F ro m C u r re n t W e ll offset well never came within
H ig h S id e A z im u th 5 (units) of the reference well
D is ta n c e
15 10° + 135° = 145°
10 20° + 135° = 155°
5 40° + 135° = 175°
5 220° + 315° = 175°
10 200 + 315° = 155°
15 190° + 315° = 145°

Horizontal Plane
The Horizontal Plane scan method calculates the horizontal distance
from the reference wellpath to the offset wellpath. It is similar to the
Travelling Cylinder method, except that the cylinder expands
horizontally irrespective of the wellbore direction. This method is not
recommended for horizontal wells that it might miss and directional
wells where it might provide late warnings as when the well does
approach, it does so very quickly. It is in Compass, but don’t use it.

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 Chapter 8: Anti-Collision Module

The following graphic displays the Horizontal Scan Method:

Offset Well Reference Well

Horizontal

Comparison
The most important difference in the methods is that they are all capable
of determining a different closest point. It is for this reason alone that
Scan Method should be defined within a company & locked, so that all
anti-collision results can be compared on the same basis.

The following diagram highlights the differences using the example

above. From the same reference well scan point, the different methods
have all found a different closest point with different values of
calculated wellpath separation.

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Chapter 8: Anti-Collision Module

When comparing scan methods assess the advantages and disadvantages

of each technique. The following table summarises the methods:

Scan Method Advantage Disadvantage

3D Closest Approach Will always find the true closest Can find a point that is behind the
point irrespective of relative well reference well assuming a wellbore
geometries. Therefore calculates the frame of reference.
minimum centre-to-centre distance.
Gives a distorted impression of
separation on a travelling cylinder
plot.

Travelling Cylinder True to the concept of a travelling Potentially confusing when two
cylinder plot, always finds a closest distances are reported against the
point ahead of the bit. same offset well MD.

Potentially confusing when a

reference well crosses vertical.

High Side + Azimuth Avoids confusion of the travelling Can miss a collision between
cylinder method when the reference wellpaths crossing perpendicular to
well passes through vertical. each other.

Horizontal Easy to understand. Should not be used to scan non-

vertical wells. Can miss a collision
between horizontal & vertical
wellpaths. Cannot be used to scan
horizontal wells.

Travelling Cylinder Scan and Near Perpendicular Intersections

The primary deficiency with the traditional travelling cylinder method
is that it can miss near perpendicular intersections if the scan

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 Chapter 8: Anti-Collision Module

interpolation interval is large. The following graphic depicts the

problem:

Travelling Cylinder Scan calculated closest point from

E4-S0 scan point to A2-S0:

— C-C Separation = 4967.40 ft

— Ratio Factor = 47.57

E4-S0 Reference Wellpath

Scanning Point
A2-S0 Reference Wellpath

On the graph above E4-S0 (right hand side) is the reference well being
scanned down. A2-S0 is the offset well. The graph displays a depth slice
that represents the orientation of the travelling cylinder at its scanning
point. As the travelling cylinder scans down E4-S0 it misses the nearby
A2-S0 well and finds a ‘closest point’ some distance up A2-S0 away
from the critical area. Even with the interpolation interval set at 25 ft.,
the A2-S0 well is missed entirely.

Warning Method
When we scan a wellpath or plan against other wellpaths, we want the
program to report only those wellpaths that pose a collision risk. To
include wellpath positional uncertainty in the assessment of collision
risk, COMPASS can report separation factors or assess against risk
based rules or depth ratios.

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Chapter 8: Anti-Collision Module

Separation Factor
Also known as ratio factor, separation factor is a value that includes
centre-to-centre separation and positional uncertainty and can be
modified to include casing diameters.

The following graphic depicts the Separation Factor Method and

Example Results:

R1 R2
Separation Factor > 1

Separation Factor = 1
Center to Center

Center to Center Separation Factor <= 1

Separation Factor = -----------------------

R1 + R2

As described in Company Setup, COMPASS enables multiple

separation (ratio) factor warning levels to be defined and a given
warning or action to be taken if such a level is exceeded. These warning
levels appear in the anti-collision report and in some of the anti-collision
graphs in the form of levels and colour shaded lines.

Depth Ratio
Will form an envelope about the wellbore representing the minimum
separation with the ratio of depth increasing until Max Radius is
reached.

A ratio of 0.01 with a maximum radius of 10m means that the minimum
allowable separation would consist of a cone expanding at 10m per
1000m reaching a maximum of 10m at 1000m from the start depth.
After 1000m MD, the minimum separation surface would represent a
cylinder about the wellpath.

Rules Based
Will use a probability of intercept to evaluate risk. A ratio of 0.01 means
there is one chance in 100 wells drilled of intercepting an offset
wellbore. The warning grid in Company Setup will contain all of the

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 Chapter 8: Anti-Collision Module

possible rules that may be assigned to a wellpath. The first row in the
grid will be the company default rule. That means when a wellpath is
selected for anti-collision this rule is automatically applied to that
wellpath. Other rules have to be assigned directly in the Offset Wells
dialog. A warning is given if the rule is determined to fail when
conducting the anti-collision scan.

Error Surface
When you select an error model you define how wellpath position
uncertainty is calculated. When selecting a scan method you define how
wellpath separation is computed. The error surface enables you to
choose how the radius of the error surface at the reference well scanning
point and the calculated closest point on the offset well are calculated.
The error surface choice allows the user to override the standard ellipse
to ellipse (default) ratio calculations in anti-collision, and instead uses
the largest dimension of error at a point to define a cone about the
wellpath. In most cases this will be major axis of the ellipsoid. Using the
circular conic method is more conservative and produces lower ratio
values and hence more warnings. The separation factor calculation
includes the dimensions of the error ellipse for both reference and offset
wells. The two error surface choices are as follows:

• Elliptical Conic
• Circular Conic

Elliptical Conic
The standard calculation of separation factor uses ellipse radius
intersections that are determined by projecting the error surface
ellipsoids onto the
centre-to-centre plane calculated between the reference well scanning
station and its closest point on the offset well. This method most
accurately implements the survey tool error models because it uses the
ellipsoid geometry and orientation as calculated by the survey tool error
coefficients along the course of the wellpath.

Because the centre-to-centre plane can intersect the error ellipsoid at any
direction from the wellpath, the resulting radius used in the separation
factor calculation ranges from the minimum dimension of the ellipse
(minor axis) to a maximum dimension (major axis). The ellipse also has
an intermediate axis with a magnitude somewhere between the minor
and major axis dimensions. Because the error radius varies in all

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Chapter 8: Anti-Collision Module

directions, the calculated separation factor is generally more optimistic

when compared against the Circular Conic method.

NOTE:

If the error model used down a wellpath is either form of Cone of

Error, the elliptical conic method returns the same results as
circular conic as the error surface does not have a major or
minor axis, but a constant radius.

The following graphic depicts an Elliptical Conic Error Surface:

Radius Projected onto Error Ellipse as Intersected by Centre to Centre

Offset Well
Error Ellipse

Minor
Major
Reference Well
R1 e R2
Error Ellipse
-C Plan
Minor
C

Major

Circular Conic
The circular conic method uses the largest dimension (major axis) of the
error ellipsoid to define a spheroid about the wellpath. Projected down
the wellpath, this becomes a cone. Using the circular conic method is
always most conservative because it uses the largest dimension of the
ellipse and therefore produces lower ratio values and hence more
warnings.

In mature areas, some companies design wellpaths by applying the

circular conic method if possible. Should a well trajectory prove
impossible to design safely using separation factors calculated by
circular conic, the operator can then use the elliptical conic method to
evaluate how the revised separation factors meet their close rules policy.

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 Chapter 8: Anti-Collision Module

Should elliptical conic prove safe, the operator might then decide to go
ahead and drill that plan.

The following graphic depicts a Circular Conic Error Surface:

Spheroidal Projection
based on Major Dimension
of Error Surface Ellipsoid

Major

R1 P la n e R2
C -C

Major

Including Casings
Casing dimensions can be modelled within the anti-collision radii. You
define these in the Casing Editor in order for the Anti-Collision
calculations to recognise them. The effect of including casings is to
reduce the centre-to-centre distance by the sum of the offset and
reference well casing radii. This models edge-to-edge distance (metal to
metal) of the casings in the calculation of separation factor. This method
assumes that casing is centred in the wellbore.

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Chapter 8: Anti-Collision Module

The following graphic depicts the Effect of Casings on Calculated

centre-to-centre Distance:

Centre to Centre Distance

12-1/4” OH Without Casing Radii 8-1/2” OH

9-5/8” Casing With Casing Radii 7” Liner

Anti-collision Scan Setup

Anti-collision functionality is available under the Anti-Collision menu.
Having defined what calculation methods are used within a Company to
perform anti-collision scans down a wellpath, survey, project ahead
section or plan, you next select a group of Offset Wells to scan against
and then configure the scan using the Interpolation Interval dialogue.
When performing a scan, the calculated results are available in a number
of graphs and reports.

Anti-Collision Offset Wells

Accessed from the Anti-collision menu, you use the Anti-collision
Offset Well selector to select offset wells to scan against in the anti-
collision scans. This window is very similar to the Graphic Offset Wells
tool but includes additional tools specific to anti-collision.

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The following graphic depicts the Anti-Collision Offset Wells

Dialogue:
Sites < 25km. Selects wellpaths from within any other
Field and Company so long as the same geodetic setup
is used as the reference data set.

Site, Well and Wellpath lists

enable offset wellpaths to be
selected manually. Simply double
click on particular wellpaths,
double click on well to select all its
wellpaths, or double click on site to
select all wells and wellpaths within
that site.

Include Principal Plan enables a

survey to be scanned against the
intended trajectory

Global Scan simply finds all

wellpaths located within a depth
increasing distance within the
wellpaths displayed in the lists

You can select whole sites, wells, or wellpaths by double-clicking items

in the lists. Selected wellpaths are preceded by a plus sign (+). Non-
selected items are preceded by a minus sign (-). Sites and wells with one
or more wellpaths selected are shown with a plus sign. The current
reference Site, Well and Wellpath, are indicated with an asterisk (*), to
indicate that they cannot be selected.

Following are some common techniques:

• Click on a site, the well list shows the wells in this site.
• Click on a well, the wellpath list shows all the wellpaths under this
well.
• To select all the wellpaths within a well, double-click the well
name. Double-click the same well name again to deselect all
wellpaths on this well.
• To select all the wellpaths within a site, double-click the site name.
Double-click the same site name to deselect all the wells and
wellpaths on this site.

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Chapter 8: Anti-Collision Module

Sites < 25km

You can select the nearby sites check box to include sites from adjacent
fields in the site list. COMPASS searches for all sites in the database (no
matter what field or customer) that have a Lat/Long within 25km of the
reference site, and includes this in the anti-collision list.

You must ensure the following for this to work:

• All sites involved must be located within a common map system

(such as Universal Transverse Mercator) using the same ellipsoid
and vertical system datum (such as MSL).
• All sites involved must use the same conventions (north reference,
local coordinate origin, and so on).
• The latitude and longitude should either be computed or entered. It
also works across zones within the same system.

Rule
This combo box will appear below the wellpath list if the Company
policy has selected Rules based anti-collision. If a rule has not been
selected for a wellpath, it is allocated the default rule which is the first
from the list in the anticollision rules grid.

Include Principal Plan

In anti-collision, you should check one wellpath against an offset
wellpath. If you want to compare an as-drilled definitive wellpath
against the proposed principal plan for that wellpath, click the Include
Principal Plan box.

Filter Offset Wells

To perform a rigorous anti-collision scan you select all wellpaths in the
current field and produce a Ladder plot or Anti-collision Report.
However, on large, multiple-site fields this can take some time to
process. A less precise but quicker and thorough method is to use the
filtering tools to pre-select only those wellpaths within a certain range
of your current wellpath.

You can filter on filtered wellpaths. For example you can select all wells
of type PRODUCER by clicking Filter All. You can then select all

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 Chapter 8: Anti-Collision Module

Producers in a range by entering a range and initial distance from

wellpath origin by clicking Filter Selected.

NOTE:

Filtering does not perform an Anti-collision Scan, it helps you

select wellpaths against which to scan.

By Type
If you assign a welltype type classification within Company Setup, you
can select wellpaths by type. In COMPASS, a welltype is a label that
you can apply against a wellpath. This enables you to scan against all
producers and injectors while ignoring exploration or P&A’s wells. This
method assumes that wellpath type labels are assigned to all wellpaths
within the data set.

By Range
Filters offset wells by a minimum range plus a proportion of measured
depth. In the example below COMPASS selects all offset wellpaths
within a range of 10ft plus 25ft/1000ft of measured depth. Note that the
range is a cube with sides of 2x the value and not a sphere.

This range... Gives this value...

Initial range 10ft

Expansion per 1000ft 25ft

At 10,000 MD the box is 520ft

2 x (10ft + 25ft x 10,000ft /
1000ft)

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In the example above, at 10,000 ft MD on the reference wellpath,

COMPASS selects offset wellpaths that fall within a box 520ft X 520ft.
The following example shows Offset Wells Scan By Range:

Scan All Wellpaths

Click on the All Wellpaths toggle to apply the filter type against every
wellpath displayed in the lists.

Global Scan
This tool does not use any of the other methods available within Offset
Wells. The global scan will force a scan of all wells in the database
within 100’ (30m) + 200/1000. This is required for company policy anti-
collision reports where the text GLOBAL SCAN has been applied will
appear. The global scan flag will be lost should you change any offset
well or range setting.

Interpolation Interval
The Interpolation Interval dialogue is used to set the anti-collision
interpolation interval type and the method for limiting results by
separation or ratio factor. You use the interpolation settings for all anti-
collision calculations and also for the error ellipse report.

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The following graphic depicts the Anti-Collision Interpolation Interval

Dialogue:

Specify how often a scan is applied

down the reference wellpath

Specify a range to limit the scan to

a specific depth interval

Specify how non-critical offset

wells are filtered out of the results

Offset wells can be referenced to

their own datum or the reference
well datum in the A/C reports

Colour List is used to colour the

proximity results by measured
depth on the reference wellpath

Interpolate
Select the Interpolate check box to interpolate the reference wellpath for
anti-collision. If interpolate is not selected the survey stations in the
reference wellpath (plan or survey) are used.

Interpolation Interval
Enter the depth step size between anti-collision sample depths. The
maximum value that can be entered is 100’ (30m).

Depths by
State the depth type to use for the interpolation interval and range
values.

• MD—The wellpaths are interpolated by Measured Depth.

• TVD—The wellpaths are interpolated by True Vertical Depth.
Interpolation by MD is recommended for anti-collision because
inadequate scanning results in high angle wells if using vertical depths.

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Depth Range
Enter the range of the reference wellpath you want check, this can be
used to scan a broad range of the reference wellpath or focus on a small
critical section using a small depth increment. Remember to reset this
option as it is used in scans of all other wellpaths and can confuse the
results.

• From —Start depth for anti-collision stations.

• To —End depth for anti-collision stations.
You can use the specified interpolation range to restrict sections of the
well drawn on the spider plots. To enable this see plot options.

Include Stations
When the reference wellpath is a survey you can include survey stations
in the anti-collision calculations. A scan is taken at the specified
interpolation interval and on each survey station. On plans the station
interval is a minimum of 100' (30m).

Limit Anti-collision Results

There are the following two criteria for limiting the offset wellpath data
that appears in plots and the scan report:

Scan Radius
COMPASS reports any wellpaths or sections of wellpath falling
within this radius. This sets the maximum separation value for the y-
axis in the Ladder Plot; the maximum radius in the travelling
cylinder plot, and is used as a reporting limit in both the 3D-
Proximity and the Anti-collision report.

Ratio Factor
COMPASS reports only those wellpaths that produce an ellipse/
separation ratio factor less than that specified.

NOTE:

When you limit the results by Scan Radius no account is taken of

the survey errors around the reference or offset wellpaths.
Limiting the results by ratio factor does consider the errors
around both the reference and the offset wellpaths. For this
reason, limiting results by Ratio Factor is considered safer.

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Offset Wellpath TVD Datum

When displaying offset well information in the A/C reports, the TVD
listed can be referenced to the reference well datum or its own active
datum.

Anti-collision Colour List

In the Travelling Cylinder and Ladder plots, you may colour the
proximity results by measured depth on the reference wellpath. Enter
into the grid the depth on the reference well to start the colour and the
colour to apply.

Result Graphics
Live graphics are available to an engineer to assess anti-collision risk.
These graphs may be used concurrently so that a user can assess risk
from different perspectives. These graphs are termed ‘live’ because they
will update if any survey data or plan trajectories change.

The following is a list of commonly used graph toolbar icons and graph
options that provide additional functionality to help assess any collision
risk:

Click... To...

Display Error Ellipses along Wellpath.

Display TVD labels along Wellpath.

Display Well labels at end of Wellpath.

Display Casing Tunnels along Wellpaths.

Access the Graphics Options dialogue that provides all

graph customisation features.

Use the mouse to read wellpath name and point MD,

TVD, etc.

When performing an anti-collision scan, COMPASS uses the current

wellpath’s definitive path as the reference wellpath. If a plan, survey or

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Chapter 8: Anti-Collision Module

project-ahead section is open the anti-collision module uses that instead

of the current definitive path.

Example Anti-Collision Analysis

To describe the Anti-Collision graphics in this section of the manual, a
planned sidetrack wellpath A1-S2 designed to launch from the parent
wellpath A1-S0 at 4300 ft MD is used as an example. Note that for
actual use, Compass can scan any plan, survey, project ahead section or
definitive wellpath.

To scan a plan:

• Open the plan to scan.

• Minimize the Plan Editor to free up space in the window.
• Perform the scan
The plan is shown in the next diagram highlighted in green with plan
section boundaries projected vertically and horizontally. Shadows are
turned on to display from where the plan launches from the parent
wellpath. If you observe the shadows, you can see where the sidetrack
departs from the parent on the horizontal and vertical projections.

All offset wells included in the scan are also portrayed. The offset wells
are located in two sites Alpha and Echo.

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The following 3D View displays a planned sidetrack (A1-S2) and offset

wells from two sites Alpha & Echo:

Alpha
Echo

Spider View
One of the traditional anti-collision graph types, a Spider Plot is a plan
view of a number of wells. Traditionally, a spider plot was easily hand
drawn by the directional driller or operations engineer as survey data
came in with measured and true vertical depths drawn adjacent to the
plotted wellpath trajectory. The spider plot displays wellpaths with East
(X-axis) against North (Y-axis).

There are 2 types of Spider Plot:

• Spider View—Local, which shows the data using local coordinates.

• Spider View—Map, which shows the data using map (grid)
coordinates.
Because it only portrays the horizontal projection of the wellpaths, it is
difficult to visually assess anti-collision risk, except perhaps if the TVD
labels are turned on where you might be able to see two wellpaths cross
or approach at a similar TVD.

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Chapter 8: Anti-Collision Module

Casing Tunnels
If you turn on casings in the Spider and Template views a tunnel is
drawn down the wellpath. The diameter of the tunnel is dependent
on the diameter column being filled in on the Casing editor.

Tips and Tricks:

• Always turn on errors to assess lateral uncertainty.

• You can use the Line Data Reader to assess TVD proximity for nearby or
overlapping wells.

The following diagram depicts a Spider View of the planned sidetrack

well within the Alpha site in the Sample Field:
Sample - Alpha
All depths referenced to Sample Alpha DFE 150.0ft
E6 (E6S0)

8000 -8000 -6000 -4000 -2000 0 2000 4000 6000 8000 10000 12000 14000 16000
8000

6000 6000
E7 (E7S2)
A1 (A1-S0)
A1-S2 E5 (E5S0)
4000 4000
Planned Sidetrack Well E7 (E7S0)
South(-)/North(+) [ft]

E1 (E1S0)
2000 2000

Alpha
Echo
0 E4 (E4-S0) A2 (A2-S0) 0
A1-S2P1
Sample - Alpha
All depths referenced to Sample Alpha DFE 150.0ft
1800 1800
0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 3200 3400 3600 3800 4000 4200 4400 4600 4800 5000

C3 (C3-S0) B2 (B2-S0) 1600

Planned Sidetrack Well

1600

-2000 B2 (B2-S1) B2 (B2-S2) 1400

7000
1400
-2000
1200 1200
6500
1000 6000 E9 (E9S0) 1000
5500
South(-)/North(+) [ft]

800 7000 800

5000 6500
5000 6000
600 4500
4500 5500 4500 600
5500 5500 5000
6000
400 4000 5000 400

-4000 200 4000

4500
200 -4000
0 4500
4500
5000
4000 0
5000
5500
6000
5500
6500
-200 6000 -200

7000
-400 6500 -400

-600 7000 -600

-6000 C5 (C5-S0) West(-)/East(+) [ft] -800

0
-1000
200 400 600 800
West(-)/East(+) [ft]
1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 3200 3400 3600 3800 4000 4200 4400 4600 4800
-800
5000
-1000
-6000

-8000 -6000 -4000 -2000 0 2000 4000 6000 8000 10000 12000 14000 16000

The above example shows that the planned sidetrack (A1-S2P1 in

middle) crosses the A2-S0 wellpath and approaches E4-S0. From this

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 Chapter 8: Anti-Collision Module

simple view you can assess that A2-S0 and E4-S0 are the only wellpaths
that pose a collision risk.

The insert graphic displays just the area about the sidetrack wellpath.
TVD labels are turned on which show that the offset wellpaths are
nearby in terms of TVD with both offset wells crossing between 5500ft
and 6000ft TVD.

Ladder View
The Ladder View plots Measured Depth of the reference well against
calculated centre-to-centre separation of one or more offset wells. You
use this graph to assess the true anti-collision risk of an offset well and
display centre-to-centre distance, magnetic interference equivalent
distance, error surface magnitudes, and ratio factor warning levels.

To set up a Ladder Plot:

1 Set the Anti-collision scan limit and the Depth range, both of which
are defined in the Interpolation Interval dialogue. The scan limit
sets the maximum value on the Y separation axis.
2 Select the wellpaths for inclusion in Offset Wells.
3 Start the Ladder Plot.

Optionally
• To change the scaling area of the graph click Graphics Options.
• Select the scan method defined in Company Setup (usually defined
by Company Policy).

The following is a list of the graph toolbar icons for the ladder view
that are commonly used to help assess any collision risk:

Click... To...

Display uncertainty ellipse magnitudes (R1 + R2)

relative to each wellpath.

Colour wellpaths with appropriate ratio factor warnings.

Display Equivalent Magnetic Distance of casing in

offset wells.

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Chapter 8: Anti-Collision Module

Click... To...

Use mouse to read wellpath name,

centre-to-centre separation, etc.

Access Graphics Options dialogue to change Y-axis

scale.

Tips and Tricks:

Always plot error bars to assess collision risk. Horizontal wells

can have a very large lateral uncertainty.

• Use the Line Data Reader to determine the exact closest point.
• Try limiting your Scan Limits in the Interpolation Interval dialogue to
more accurately assess critical areas.

The following Ladder Plot displays calculated separation of all offset

wells located in the Alpha and Echo Sites. The Echo wells are those that
come in from the top-left of the plot:
Plan: A1-S2P1 (A1/A1-S2)

8000
Centre to Centre Separation [ft]

7000

6000

5000

4000

3000

2000

1000 E4-S0
A2-S0

0
4400 4600 4800 5000 5200 5400 5600 5800 6000 6200 6400 6600 6800 7000 7200 7400 7600 7800 8000

Measured Depth [ft]

The above plot displays the centre-to-centre separation relative to the

planned sidetrack wellpath (A1-S2P1). The plan itself is not visible, it is
plotted along the X-axis. From this graph we can see that three offset
wells require investigation:

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 Chapter 8: Anti-Collision Module

• the wellpath that departs from the X-axis at 4600 ft

• the wellpath that approached at 6300 ft
• the wellpath that approaches at 7600 ft
All other wellpaths scanned against can be discounted as anti-collision
risks using this graph as they don’t approach the sidetrack and if you
include error surface magnitudes, there is no overlap of the error
surfaces against the X-axis. The wellpaths that interfere are A1-S0, the
parent wellpath, A2-S0, and E4-S0 as seen in the Spider View on the
A1-S2 plan. A1-S0 at 4600 ft displays where the sidetrack launches
from the parent, so it poses no anti-collision risk.

The graph above has error bars turned on for each wellpath. These error
bars plot the sum of the uncertainty ellipses of both the plan and each
offset well (R1 + R2) assuming the error surface selected in Company
Setup (Elliptical Conic/Circular Conic). The reason why the planned
sidetrack wellpath has no error bars plotted along the X-axis is because
its own error surface magnitude (R1) changes for each offset well. So R1
error magnitudes are included in the error bars plotted against each
offset wellpath.

In this example, the Ladder and Spider Views enable an engineer to

determine that the only wellpaths that pose any form of anti-collision
risk are A2-S0 and E4-S0. You can use the Anti-Collision Offset Wells
tool to turn off all other wellpaths in the anti-collision scan.

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Chapter 8: Anti-Collision Module

The following graphic depicts a Ladder View displaying A2-S0 and E-

S0 collision risk:
Plan: A1-S2P1 (A1/A1-S2)
E4-S0: X: 7625.00 MD: 7717.06 INC: 49.76 AZ: 268.10
Y: 155.81 TVD: 5766.78 N/S: 533.97 E/W: 3270.81
900
Centre to Centre Separation [ft]

800

700

600
A2-S0: X: 6200.00 MD: 5964.02 INC: 49.23 AZ: 79.02
500 Y: 152.68 TVD: 5290.24 N/S: 510.63 E/W: 1942.96

400

300

200

100

0
5400 5600 5800 6000 6200 6400 6600 6800 7000 7200 7400 7600 7800

Measured Depth [ft]

The above ladder graph displays the collision risk determined for A2-S0
and E4-S0 wellpaths. The other wellpaths in the Alpha and Echo sites
are turned off using the Offset Wells tool.

Highlights are added that display the line data reader results for the
closest points. The wellpaths themselves are shaded blue, green, and red
to display warning factors. Both wellpaths have reasonable separation
(152.68 and 155.81 ft) at the calculated closest point; however, with the
error bars turned on, you can see that the planned sidetrack well error
surface overlaps on both wellpaths. This occurs where the error bars
intersect the X-axis.

Over this area, the calculated separation factor is less than 1.00, which
means that within the accuracy of the survey tools, you cannot tell if the
wellpaths are going to collide or not. This is an unsafe situation. The
only solution here would be to redesign the planned sidetrack trajectory.

Equivalent Magnetic Distance

The Equivalent Magnetic Distance is a broad red line drawn on the
ladder view to show the combined magnetic effect of multiple casing
strings on the current plan. This line may be selected from the options
tab in the Graph Options or from the Tool Bar icon.

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The Equivalent Magnetic Distance line shows where the well plan
passes close to existing wells, and hence where magnetic interference
from casing can be expected. It is useful in survey program design, when
determining where to plan the switch from gyroscopic to magnetic
single shots. A simple rule of thumb is if the magnetic equivalent
distance is less than 50ft, then gyro survey tools should be used.

The scan differentiates drilled wells from planned wells by the status of
the survey program; only those wells with real surveys are assumed
drilled. Note that a program which consists of a planned section tied to
real surveys will have status planned, and will not be included in the
scan, even over the depth interval covered by the real surveys.
Additionally only the part of the wellpath deeper than the sidetrack
depth is included in the scan.

The perpendicular distance to all neighbouring drilled wells is

calculated at intervals down the planned well. The combined magnetic
effect of all casing strings is then expressed as an Equivalent Distance
to a single casing string (using the inverse-square law for magnetic
fields). For example, if there are four casing strings at 18, 22, 25 and 27
metres distance, their combined magnetic interference would be
equivalent to a single string at a little over 11 metres distance. The
algorithm does not consider casing diameters.

Ratio Factor View

The Ratio Factor View plots measured depth of the referenced wellpath
against the Ratio Factor (Separation Factor) with the offset wellpaths.
The plot automatically plots the warning levels as defined within
Company Setup. This enables a quick review of the separation factor
against warning levels defined as company policy.

It too can be a very effective first place to look to determine the anti-
collision risk associated with an offset well. The only drawback when
compared to the Ladder View, is that you cannot determine the centre-
to-centre separation.

Tips and Tricks:

• Use Graphics Options to change the vertical axis scale using Fixed Range
to something reasonable if using Scan Radius to limit results.

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The example below shows the same conclusions that were determined
using the Ladder View. Both wellpaths are unsafe with ratio factors
dipping below the lowest safe level ‘STOP DRILLING NOW’.

Plan: A1-S2P1 (A1/A1-S2)

5.0

4.0
Ratio Factor

3.0

2.0
Advise and Monitor
Shut-in producers
STOP DRILLING NOW
1.0

0.0
5400 5600 5800 6000 6200 6400 6600 6800 7000 7200 7400 7600 7800

Measured Depth [ft]

Reduced Error Bars with Depth

With the elliptical conic method, it is possible to observe declining
combined error surface magnitudes with depth seen most prominently
on the ladder and ratio factor views. This can be observed in the above
ladder graph for A2-S0 from 6400 ft to 6850 ft, where R1 + R2 can be
seen to reduce, and on the ratio factor view where it increased over the
same depth range before reducing again from 6900ft.

This phenomena is not an error and is due to the relative orientation of

the reference wellpath (our plan in this example) and/or offset wellpath
ellipsoids with increased depth. The reduced error bars occur when the
centre-to-centre plane changes orientation, about one or both of the

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 Chapter 8: Anti-Collision Module

ellipsoids from intersecting from a large axis to a relatively smaller axis.

The following diagram depicts this situation:
Error Surface Intersection

D E

R1 + R2
C
F
B
A G
H
I J K
Offset
Wellpath Measured Depth

Reference
Wellpath
R1 A

lan e
en t re P
t r e- C
B
C en

R2 C
TD
D

Centre-Centre Plane intersects

(R2) through major axis then E
around to minor axis of ellipse. F
G
H
I
TD K
J

Travelling Cylinder View

One of the traditional anti-collision plot types, the Travelling Cylinder
plot shows the polar positions of offset wells relative to the reference
wellpath centre. This is the distance to the offset well at an angle that is
either measured from wellbore high side (toolface) of the reference
wellpath or North (azimuth only when using Horizontal plane scan
method). The largest radius of the plot is the scan limit and the distance
scale is displayed to the left of the graph. The interpolated labels on the

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Chapter 8: Anti-Collision Module

traces are the measured depth of the points on the reference wellpath not
the offset wellpath.

NOTE:

• The reference wellpath is never shown on the travelling cylinder view, it is

assumed to plot in the centre of the graph.
• The centre-to-centre separation shown on the travelling cylinder graph is
applicable for the configured scan method. Therefore, the travelling
cylinder graph is available for all scanning methods, not just the travelling
cylinder scan method. Do not confuse the travelling cylinder graph with the
travelling cylinder scan.

To set up a Travelling Cylinder Plot

1 Define the interpolation frequency and range limit in Interpolation

Interval.
2 Select the wellpaths for inclusion in Offset Wells.

Optionally
3 Select the scan method defined in Company Setup (usually
company policy).

To determine the distance between the reference wellpath and an offset

wellpath at a given depth, follow the trace of the offset well until you
find the MD you require. Measure the distance from the centre of the
plot to this point. That is the distance between the reference wellpath and
the offset wellpath at that MD on the reference well. The line data reader
is useful for determining separation.

If the offset well point is along the 180 degree line the offset wellpath is
below your reference wellpath and if along the 0 degree line the offset
wellpath is above your reference wellpath. Any other direction and the
offset well is off to the left or right as you look down the well. The 90-
270 degree line separates offset well positions that are above the
reference wellpath or below assuming a wellbore reference.

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Here’s a list of the toolbar icons for the travelling cylinder view that are
commonly used to assess collision risk:

Click... To...

Toggle error ‘pedal’ surface on/off

Toggle error shadows on/off

Show error surface magnitudes. The radius of the circle

is the sum of the error radii (R1 + R2).

Colour wellpaths with appropriate ratio factor warnings.

Display MD labels along Wellpath. Depths are for the

reference wellpath.

Display offset Well labels at end of Wellpath.

Interactively travelling cylinder view or depth slice, used

to manually scan down the reference wellpath.

Use the mouse to read wellpath name, centre-centre

separation, etc.

Access Graphics Options dialogue to customise plot.

Tips and Tricks:

• Turning on Well and depth labels while in interactive mode, enables you
to maintain a reference.
• Colour shading provides a quick way to see where the critical intervals are
along each offset wellpath.
• If you don't see depth labels on the plot, you can set a labelling exclusion
zone, see Graphics Options.

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The following graphic depicts a Travelling Cylinder View with

Offset wellpath and error surface plotted:

0
748 748 Colour To Depth
5000
330 30 5500
600 600 6000
6500
7000
7500
400 400 8000
This depth range
300 here displays 60
overlap of the offset and Wellpath A2-S0 is above and to
reference well ‘pedal’ curves. 5200
5100
5300
5000 the right.
5400
55004900
4800
200 200 5600 4700
5700 4600
5800 4500
5900 4400
6000
6100 4300
0 270 90
6200
6300
6400 Wellpath A2-S0 is now below
200 200 6500 moving from right to left.
6600
6700
6800
240 6900 120
400 400
7000
7100
7200
7300
7400
7500
600 7600 600
7700
7800
210 7900 150
748 748
180
Reference Toolface Angle [deg] vs Centre to Centre Separation [ft]

The above graph refers to the A2-S0 wellpath of our example only,
E4-S0 has been turned off for clarity. The graph shows that the A2-S0
wellpath initially appears within our scan limit (10000 ft scan radius)
above and to the right of our reference well as it would appear as
looking down the reference well.

With increased depth, A2-S0 approaches to its closest point whereby the
error surfaces are overlapping (ratio factor = 0.67). A2-S0 then moves
below our wellpath and moves from right to left.

The graph clearly displays the overlap of the combined (offset +

reference) pedal error surface with the origin of the plot. This indicates
an un-safe drilling condition, again, the sidetrack planned trajectory will
need to be re-designed and/or different survey programs planned or
conducted on the wellpaths to reduce the size of the error surface.

Pedal Curve Error Surface

The travelling cylinder plot provides a tool bar icon that enables a
statistically correct form of the combined error surface to be plotted
against the offset wellpaths. This error surface is known as a pedal
curve, also referred to as ‘footprint’, dumb-bell or a peanut shape. This
shape is different than all other graphics within COMPASS where an
ellipse(oid) or sphere(oid) is depicted.

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The elliptical error surface is usually used to represent the positional

uncertainty of a point on a wellpath. This uncertainty can be described
mathematically using a 3D covariance matrix which describes the
mathematical derivation of the dimensions and orientation of the
ellipsoid:

2
σ n σ ne σ nv

3DCovarianceMatrix = ( C nev ) = σ 2
σ σ
ne e ev
2
σ nv σ ev σ v

where sigma n, e, and v refer to the uncertainty in an ‘earth centred’

frame of reference (north, east & vertical)

The radius of the error ellipse in any direction does not represent the
positional uncertainty in that direction. Restricting the formulae to
horizontal uncertainty, the expression to calculate positional uncertainty
for any azimuth A is:

2
σ n σ ne cos A 2 2 2
σ = cos A sin A = σ ⋅ cos A + σ ⋅ sin 2A + σ ⋅ sin A
A 2 sin A n ne e
σ σ
ne e

The resultant shape of this surface is a pedal curve. This shape can be
drawn from the standard error ellipsoid by drawing tangent lines in all
directions from the ellipsoid origin and then drawing a set of
perpendicular opposing lines connecting the 1st point of contact of the
line onto the ellipse.

The following graphic displays how a pedal curve can be constructed

from the systematic error
ellipse:

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Chapter 8: Anti-Collision Module

Pedal Error Surface

Standard Error Ellipse

The pedal curve is essentially the combined ellipse distance (extremity

to extremity) + in all directions. The travelling cylinder plot assumes
that you are not on the plan and that you can approach the offset wells
in any direction. So the combined ellipse distance computed in old
Compass is only in one direction, with Pedal curves the no-go zones are
determined for all directions (i.e 0-360) about the reference & drawn on
the offset. It’s a better representation of where you can go. Note that
other limits are combined in the no-go zones, such as casing diameters
& arbitrary limits like 10m where configured. If you use risk based
rules, then you are no longer comparing ellipses and the pedal curve
routine can draw weird shapes like butterflies.

Interactive Travelling Cylinder View

The Depth Slice tool bar icon activates the interactive travelling
cylinder view. The view switches to show offset data for a single depth
on the reference wellpath. The same functionality is available within the
3D Proximity view.

Using the scroll bar at the right hand side of the plot, you can change the
measured to at any point along the reference wellpath. Like the 3D view,
you can also use the keyboard control and up, down, page down, page
up, home and end buttons to move along the reference wellpath.

For each measured depth, COMPASS plots the range and orientation
from high-side to the offset wells. In the bottom window the wellpath
centre-to-centre distance and separation factor are displayed for each
offset wellpath. At any depth, if the ratio factor falls below one of the
company warning levels, that warning also appears.

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 Chapter 8: Anti-Collision Module

The circle/ellipse around the offset well and reference wells represent
the error ellipse’s geometry at the current scan depth.

The following graphic depicts a Travelling Cylinder Depth Slice with

Projected Ellipse Extents:

Ellipse Projected Extent

Reference Well Offset Well

Centre-Centre Plane

Ce
ntr
e-
C en
tre
P la n
e

Offset Well Ellipse

A2-S0 @ 6850 ft
Reference Well Ellipse
S.F. = 0.67
Ce
ntr
e-
Ce
ntr
eP
lan
e

The above example displays the interactive view with the depth set to
6850 ft on the reference well. The position of the calculated closest point
on A2-S0 is shown with its uncertainty ellipse at the depth.

The uncertainty ellipse of the reference well at 6850 ft is also shown

projected about the origin. Note that even though the ratio factor is less
than 1 (0.67) that the ellipses do not appear to overlap. This is because
the ellipses are displayed using the wellpath frame of reference. If you
plot the centre-to-centre plane and then project those ellipses onto the
centre-to-centre plane, you can see (above) that the ellipses do overlap.

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3D Proximity View
The 3D Proximity View provides both a 3-Dimensional graphic
representation of selected well paths and a tabulated list of anti-collision
results. The graph is essentially a 3D live graph with additional tools
useful for anti-collision assessment. For visual assessment, this graph is
very useful to quickly obtain a picture of what is happening relative to
the reference wellpath. For absolute anti-collision assessment, the
Ladder View and the Anti-Collision Report provide a quicker method
for determining risk.

To set up a 3D Proximity graph:

1 Set the interpolation depths and scan limit in the interpolation

interval dialogue box.
2 Select Offset Wells to be shown in the view.
3 Start the Graph by selecting it from the menu.

Here’s a list of the toolbar icons for the 3D Proximity view that are
commonly used to assess collision risk:

Click... To...

Project a shadow of the wellpaths on to the horizontal and both

vertical planes.

Replace the north and east walls with a vertical grid.

Display the depth plane at the current depth.

Display an ellipse down each wellpath indicating the positional

error at each point.

Interactive Scroll Bar

3D Proximity computes the distance between the reference wellpath
and selected offset wells for a given depth on the reference wellpath.

Use the vertical scroll bar at the side of the graphic to change the
reference wellpath depth. As you do so, the closest point on nearby
wells, marked with a cross, changes. The positions of these markers
can change for different scan methods.

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The wellbore centre-to-centre distance and separation factor are

tabulated for each offset well. The maximum separation reported is set
in the interpolation interval dialog box under anti-collision scan limit. If
no values are reported for a particular wellpath, this means that the
calculated results fall outside your scan limits.

Tips and Tricks:

• Click and drag the left mouse button to rotate and tilt the 3D frame.
• Click and drag (up/down) the right mouse button to zoom in and out.
• Use the keyboard buttons to rotate, zoom or step the wellpath point.
• To differentiate between wells, click on each wellpath name in the legend
box. The wellpath is highlighted on the graphic.
• To adjust the radius of the depth plane, use Interpolation Interval
dialogue and change scan radius.
• Try not to rotate, zoom in and out too often or too quickly. It is very easy
to become disoriented.

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Chapter 8: Anti-Collision Module

The following graphic depicts a 3-D Proximity View:

A1-S2 Planned
Sidetrack

E4-S0 Offset Well

A1-S2 Ellipsoid

E4-S0 Ellipsoid

A1-S0 Parent
Wellpath

A2-S0 Offset Well

The above example portrays a planned sidetrack well (A1-S2) together

with the parent wellpath (A1-S0) and the offset wells A2-S0 and E4-S0.
Note that E4-S0 has been drilled from another site and so comes in from
the right. From this graph you can see that the planned sidetrack well
appears to have a close approach to both offset wellpaths. It also shows
that the E4-S0 error ellipsoid is much larger than the A2-S0 error
ellipsoid. Perhaps this anti-collision problem could be solved by
surveying E4-So with a more accurate survey tool? This confirms the
other diagnosis made using the other anti-collision graphics.

Reports
Formatted and ASCII file versions of the two Anti-Collision reports are
available from the Anti-Collision Reports dialogue accessed from the
Anti-Collision menu. Currently, there are no report options. There is
also no ability to customise report content, as is available in the Survey
and Planning reports.

The following screen shot displays the Anticollision Reports dialogue:

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Select one of two A/C

reports to view

Generate formatted
version of report

Generate text version

of report

Anti-Collision Report
The anti-collision report is a very quick and quantitative way to evaluate
collision risk for a number of offset wells. To generate this report,
COMPASS runs down the current well at intervals and calculates the
distance to each offset wellpath. The report consists of Page Header,
Report Header, Summary and a Results section for each offset wellpath.

To set up a data scan report:

1 Select Offset Wells for the scan.

2 Define the interpolation interval, range and scan limit in the
Interpolation Dialogue.
3 Start the Report, from the anti-collision menu select Anti-Collision
Reports, the from the list select Anti-Collision Report.

Definition of sections:

Page Header
Printed at the top of each page the page header contains the name of
the reference wellpath, date and time and page number. Using
Report Setup under the Utilities menu it can also be setup to display
Company & User logos.

Report Header
The report header shows the parameters setup in interpolation
interval and the error model and warning method that are defined in
Company Setup.

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Summary
The summary section shows the point of minimum separation factor
between the reference and offset wellpaths. Because separation
factor considers the size of the wellpath error ellipsoid, the point of
minimum separation factor can not coincide with the closest centre-
to-centre distance.

Results
The results section contains 11 columns:

Column... Description...

Reference MD and TVD Columns 1 and 2 show the measured depth

and true vertical depth of the point on the
reference wellpath. These depths are
referenced to the drilling datum on the
reference wellpath.

Offset MD and TVD Columns 3 and 4 show the depths of the

nearest point on the offset wellpath from the
point on the reference. Note: The measured
depth and vertical depth on the offset wellpath
are referenced to the drilling datum of the
offset wellpath. The result depends on the
Scan Method selected.

Major Semi-Axis Error Ref. Columns 5 and 6 are the ellipse of uncertainty
and Offset major semi-axis dimensions of the reference
and offset wellpaths. When you scan with 3D
Closest Approach or Travelling Cylinder
separation, the error quoted is the maximum
"radius" of the error ellipsoid in a plane
perpendicular to the wellpath at that point.
When scanned by Horizontal Plane the error
is the radius of the ellipsoid in a horizontal
plane. The size of the error depends upon
surface errors and survey tools assigned the
current and any parent wellpaths.

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Column... Description...

Orientation: AZI, TFO Orientation to set the reference wellpath to

(HS) or TFO+AZI move towards the nearest point on the offset
wellpath. The angle displayed will depend on
the anticollision method chosen for this
Company.
Closest Approach – TFO (HS) Highside
toolface angle.
Horizontal Plane – AZI – Azimuth angle from
reference point to offset well at the same
vertical depth.
Traveling Cylinder – TFO (HS) Highside
toolface in traveling cylinders plane.
Highside + Azimuth – TFO+AZI Toolface +
the current well azimuth.

*High and Right High and Right are the distance that the offset
wellpath is high and right of the centre as
plotted on a Travelling Cylinder plot.

Ctr to Ctr Distance Distance from the centre of the reference

wellpath to the offset wellpath in the plane
defined by the anti-collision method.

*Edge To Edge Distance This is the distance from the edge of the error
ellipsoid around the reference wellpath to the
edge of the error ellipsoid around the offset
wellpath.

*Separation Factor The separation factor at that point. See

warning method for a description of
separation factor. This column does not
appear in ‘rules based’ anti-collision.

Warning In company set-up you may enter text to be

printed on anticollision reports when a
separation factor threshold is passed. In ‘rules
based’ anti-collision, the warning ‘Passed’ or
‘Failed’ appears for the appropriate rule for
this wellpath.

*The columns marked with an asterisk do not appear on ‘rules based’

reports and are substituted with the following:

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Chapter 8: Anti-Collision Module

Column... Description...

No Go Area The No-Go Area appears on ‘rules based’

anti-collision reports. It is the combined
distance from the offset wellpath that must
not be exceeded. It is the sum of the combined
errors (in the vector between the 2 wells), the
casing and hole radii and the tolerance radius
defined in the rule.

Casing Is the casing diameter on the offset well.

Allowable Deviation (from This is the maximum distance that can be

plan) drilled from the plan in the direction of the
offset wellpath. It is essentially the Ctr-Ctr
distance minus the No Go Area. In designing
the well plan, the allowable deviation value
should not be less than or equal to zero, or
there will be no room to drill the well.

Error Ellipse Report

The error ellipse report describes the geometry and orientation of the
uncertainty ellipse with depth along the reference wellpath. The report
is a very useful way to assess how the ellipse geometry develops along
the wellpath. The error ellipse is computed from parameters contained
in the survey tools assigned to the active wellpath in the survey program
editor.

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To set up an ellipse survey report:

1 To generate an error ellipsoid around a wellpath, you must assign

tool codes to the wellpath. To assign tool codes to a survey see
Survey Setup and to assign tool codes to a plan see Plan Setup.
2 Then you must assign the surveys or plan to a Definitive path, by
either adding surveys or through the history editor.
3 State the interpolation interval, and range for the ellipse data in the
Interpolation Dialog.
4 Start the Report, fire up reports from the anti-collision menu and
then select Ellipse Survey Report from the available list.
NOTE:

All ellipse dimensions reported are half-axes, or radii and not

diameters.

Definition of Columns:

This column... Means this...

MD Measured depth

Incl Inclination

Azim Azimuth

TVD True vertical depth

Uncertainty The radius of the error envelope from and its

confidence level is stated in standard
deviations from the mean, as noted in the
header of the report.

Bias The amount the ellipse centre is displaced

from the centre of the wellpath. Bias is caused
by error sources that have an unbalanced
distribution. For instance, magnetic surveys
often plot to the north of gyro surveys, due to
the earth’s magnetic field polarising the
drillstring in a consistent direction.

High Side Uncertainty (cross Semi-axis error in position on the high side of
borehole plane) the hole (toolface 0/180).

High Side Bias Error in position lateral to wellbore.

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This column... Means this...

Lateral Uncertainty Semi-axis value of error lateral to wellpath in

horizontal plane (toolface 90/270)

Lateral Bias Lateral Bias component for the ellipse relative

to the direction of the wellpath

Vertical Uncertainty Semi-axis value in the vertical direction from

the wellbore depth.

Vertical Bias Vertical Bias Component

Magnitude of Bias This is the total displacement of the ellipse

from the centre of the borehole.

Semi Major Uncertainty This is the largest dimension of the ellipse.

Semi Minor Uncertainty Minor axis dimension

Semi Minor Azimuth The direction of the horizontal minor axis

from local north.

Tool Survey tool used to measure this survey

station.

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The following graphic portrays parameters described within the Error

Ellipse Report:

Compass Error Ellipse Report Semi-Minor Unc

Plan View
North
3 Dimensional View Semi-Min.Azi
Lateral Bias

Lateral Unc.
Semi-Major
Unc.
X Borehole East

Vertical Section View

in Borehole Azimuth
Lateral Unc.

Bias High Side Unc.

High X Borehole
Side Unc.
Vertical Unc.
X Borehole Plane = High
Side Bias
Perpendicular to wellpath Vertical Bias
TVD vector at depth of interest TVD V.Section

Survey Bias
Survey Bias is the tendency for the most likely position of a wellpath as
determined by the error model to be different than its position as
calculated from survey data. This is demonstrated when the error model
calculates an error surface which is not centred about the wellpath
trajectory. For example, magnetic surveys tools can have azimuthal bias
due to a systematic effect of drillstring magnetisation. Gyrocompass
error can occur due to gimballing effects.

The following graphic demonstrates this concept. The wellpath to the

left displays Wolff & de Wardt error ellipses which are centred on the
trajectory calculated from the displayed survey stations. The wellpath to
the right displays ISCWSA error ellipses which are offset to the
calculated trajectory. A dotted line displays the ‘most likely trajectory’
which passes through the centre of the ellipses, the solid line displays the
calculated trajectory. ‘Most likely’ is used as a description because the
error model is indicating that statistically the wellpath position would be
at the centre of the error surface.

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Survey Station

Calculated Trajectory

‘Most Likely’ Trajectory

Survey Bias
ISCWSA Error Surface Displaying ‘Bias’

Systematic Ellipse Error Surface

In COMPASS, Survey Bias is shown on all ellipse drawings, it’s just

that the ISCWSA model is the only error model in COMPASS that
generates bias errors so it is not observed on Systematic Ellipse error
surfaces.

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 Chapter 9: Site Optimiser

Site Optimiser

Introduction
When drilling to a number of targets, you can use the Site Optimiser to
determine the optimum site location to minimise the drilling required to
hit all targets defined for the Site. The Optimiser plans a series of 2D
Slant or S wells to each target aiming point. Results are displayed with
the total well drilled, maximum inclination held, maximum measured
depth, and total displacement. You can manually adjust the site centre
or use an optimise function that automatically determines the site
location.

Note: the simple plans Site Optimiser creates to determine the best
location are not saved when you close the tool. When you determine the
best drilling location click OK to update the Site centre or click Cancel
to exit without updating the location.

Similar to other tools in COMPASS, the Site Optimiser consists of two

windows:

• Optimiser, which is used to control and view results,

• Viewer, which is used to display the relative positions of the site
centre and target locations.
Both dialogues come with specific tools.

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Site Optimiser
The following graphic depicts the Site Optimiser:

Target List which displays the MD,

TVD and maximum inclination to
drill a well to the target location.

Design Constraints enables user to

Summary Statistics
define directional drilling parameters for
displays worst case
Slant and Optimum Aligned wells to hit
directional parameters for
targets.
all wells to hit all targets.

Set Site Centre enables user to manually adjust site

As usual, Notepad feature enables
location using Easting/Northing textfields, +/-100(m)
results to be output to ASCII file.
buttons, or Optimise which automatically calculates the
best site location to minimise drilling

Targets
To use the Site Optimiser, you must define target locations using either
Map or Geographic co-ordinates in the Target Editor. If you enter
targets in Local Co-ordinates (i.e. relative to site centre) then the targets
move when you move the site. When design constraints are entered, the
targets list contains a short description of the plan to each target. The
description includes the target location, displacement from site centre,
maximum inclination of the well, and its MD and TVD.

Design Constraints
This area is used to define which type of well design is used to drill to
each target.

You have two choices:

• Slant well
• Optimum Align using dogleg severity.

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The Kick Off field enables you to define a typical KOP. If you are using
optimum align, the optimiser uses the Dogleg entered in the DLS1 field
for Slant wells. Also note that you can increase DLS1 and DLS2 using
the Optimiser if a plan to a particular target is not possible using the
parameters entered.

The optimiser assumes a well is used for each target in the site list, no
wells are planned that intersect multiple targets. Also note that all wells
are drilled in a vertical section, they are 2D.

Site Centre
This area enables you to manipulate the site centre location. There are
three ways to change the site location:

• Type in the new Centre Location map coordinates.

• Click one of the buttons to move the site north, south,

east or west by 100 map units.
• Click the Optimiser Viewer , then move the cursor and click
the left mouse button on the required location.
When you decide on a location click Set Site Centre to assign the
current coordinates to the current Site.

Click Optimise to sums the target Eastings and Northings, and divide
both by the number of targets to provide a first guess start location.

Optimiser Viewer
This graph is a plan view of the site targets and the site centre connected
by lines that represent each plan. The optimiser view appears
automatically when site optimiser is shown.

The site optimiser viewer enables you to toggle between UTM (Map)
and Local co-ordinates display.

You can change the site centre by entering the coordinates in the edit
controls or by clicking the graph when it is displays Map coordinates.

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Chapter 9: Site Optimiser

Results
As you move the site location COMPASS reports the following:

This... Means...

Maximum Angle The maximum inclination of any wellpath.

Average Angle The sum of the final inclinations divided by

the number of targets.

Maximum MD The maximum measured depth to any of the

targets.

Total Measured Depth The sum of the measured depth to all the
targets.

Maximum Displacement Horizontal displacement to the furthest target.

Total Displacement The sum of all the horizontal displacements to

all targets.

Centre Location The origin for the well plans.

Kick-off The depth at which each wellpath launches.

Build Rate The build rate for kick-off.

The maximum results also reports which target required this worst case
value.

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 Chapter 10: Wallplot Composer

Wallplot Composer

Introduction
The Wall Plot Composer is used to create and customise plot layouts for
windows, file, or professional hardcopy output by creating a template of
the page layout that can be saved an reused. A wallplot consists of any
combination of graphical and data elements generated from COMPASS,
in addition to bitmaps or windows metafiles constructed elsewhere. The
only limitation is the amount of real estate available on hardcopy.

The following graphic depicts an example Wallplot with Graphs Data

Boxes and a logo:
G All Angles Relative
Field: Sample
Site: Alpha T To Grid North
M
Well: A1
Wellpath: A1-S2 Grid North: 0.00
True North: -0.65
Plan: A1-S2P1 Magnetic North: -4.18

Graphics include plan views, logos, 1500

vertical section.

-646
South(-)/North(+) [500m/in]

1000

Each graph or data element may be

0
customised; for example to display 0°

different scales, plan section boundaries 500

or inclination labels, fonts, colours - any 24
38
21 9
34
18 1524

feature available in the live graphs.

2

646 5°
15 9

T20a
24

10°
12

15°
0 0610 T20
1
True Vertical Depth [m]

91 05

20°
3
4

0 500 1000 1500

250°°
1291 3 5°°
340 °
45
550°
6650°5°°
0°
775°
79°
75°
6750°°

All data derived elements are taken from West(-)/East(+) [500m/in]

61°

T20a
the currently open wellpath, in this case a 24° T20 WELLPATH DETAILS
planned sidetrack well. 1937 A1-S2
Parent Wellpath: A1-S0
Tie on MD: 1310.64
250°° Vertical Section Origin: Slot - A1 (-0.86,5.17)
3 5°
3 ° Vertical Section Angle: 49.69°
40 5°
4 PLAN DETAILS
550°
660°°

Rig:
7 5°
5

750°
80°°
85°
90°

90°

85°

2583 Depth Reference:A1-S2P1

Sample Alpha DFE 45.72m
90°

90°

Version 1
08/05/1996
Start Point
MD Inc Az TVD N/S E/W
1310.64 23.75 45.87 1275.55 151.07 163.99
3228 REFERENCE INFORMATION
Co-ordinate (N/E) Reference: Site Centre Alpha, Grid North
Data Elements include Header Box, Vertical (TVD) Reference: Sample Alpha DFE 45.7 above Mean Sea Level
Section (VS) Reference: Slot - A1 (-0.86,5.17)
Norths Arrow, Well and Wellpath details, Measured Depth Reference: Sample Alpha DFE 45.7 above Mean Sea Level
Calculation Method: Minimum Curvature
Casing details, Plan section details, target Plan: A1-S2P1 (A1/A1-S2)
3874 Created By: Aberdeen Drilling Support Date: 24/05/1999
details, and Approval box.
0 646 1291 1937 Checked: ____________________ Date: __________
Approved: ____________________ Date: __________
Vertical Section at 49.69° [m]
CASING DETAILS SECTION DETAILS TARGET DETAILS
No. TVD MD Name Sec MD Size Dip Dir TVD N/S E/W DLeg TFace VSec No.Target TVD N/S E/W Target
No casing details fall on the
1 wellpath.
1310.64 23.75 45.87 1275.55 151.07 163.99 0.00 0.00 220.09 1 1615.44 189.14 705.89 T20a
2 1803.48 79.40 94.86 1579.48 205.43 514.47 3.94 55.16 522.54 2 1791.00 92.98 1062.74 T20
3 1998.92 79.40 94.86 1615.44 189.14 705.89 0.00 0.00 657.97 T20a
4 2168.45 60.89 108.07 1672.99 158.72 861.26 3.94 148.18 756.79
5 2411.02 60.89 108.07 1791.00 92.98 1062.74 0.00 0.00 867.91 T20

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Chapter 10: Wallplot Composer

Wallplot Composer Editor

You use the Wallplot Composer Editor to:

• Display a graphic WYSIWYG view of the plot template.

• Select the paper size to set how much real estate is available for the
plot components.
• Select the print device by determining which plot driver to use to
display WYSIWYG.
• Add multiple graphs and data boxes to the plot by selecting
components from the right click menu
• Resize and re-scale each plot component.
• Read wellpath co-ordinates, distances, and angles using the
window reader.
• Read data points from wellpaths using the line data reader.
• Enlarge the view with a zoom function.
• Select offset wells to include in the plot.
• Customise the contents of each sub-plot or data box.

Plot Device & Page Description

You can select a plot output device and paper size by double-clicking on
the wallplot whitespace to fire up Graph Options for the entire plot. This
launches the Windows Printer selection dialogue that enables you to
select from any installed printer driver available on the PC. The printer
driver is used to determine how to present the plot components on the
Conductor and enable WYSIWYG images to appear. The dialogue also
enables you to select paper size and determines how much real estate is
available for plot objects.

Paper dimensions are defined in the following units:

• % - Proportion of the paper the drawing occupies.

• Points - Printer resolution expressed in dots per inch, with each dot
equal to one point.
• In, cm, and mm – measured lengths

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Wallplot Components
The right click menu enables you to select which plot items appear in the
wallplot. A drop-down list enables you to include all COMPASS plots
and data structures. Each component has an X and Y origin as well as a
a width and height. The following graphic depicts the Plot Component
Origin (Start X & Y) Width and Height:

0, 0

Start Y

Start X
H
e
i
g
h
t

Width

Start X and Start Y is the position of the top left corner of the graph or
data component from the plot origin located top left hand side. Width
and Height are the dimensions of the graph box shown here.

With several graphs on a plot some components can overlap. The

component order determines which components are overwritten. Move
to front, Move to back tool bar icons enable the user to configure which
components overwrite other components.

Component Adjustment
You must select a component to change its appearance. To select a plot
component, click it with the left mouse button. When a component is

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Chapter 10: Wallplot Composer

selected it is enclosed in a red highlight box with a resizing handle on

each side and corner of the box. You resize the component by clicking
the handle and dragging it to the desired position.

To move a selected component, adjust the cursor over any part of the red
line until a double arrow appears. Hold down the left mouse button, then
drag the component to the desired location. Release the mouse button
and the component’s start X and Y position are updated in the Composer
spreadsheet.

The following graphic depicts the Wallplot Composer with an example

Wallplot:

To customise a component, double-click it to display its Graph Options

dialogue box. The plot or data box displays several tabs that are
dependent on the component selected. These tabs enable you to select
graph scale, grids, fonts, line styles, and to toggle options such as
display error ellipses, symbols, formations, casings, and so on.

To adjust settings for the entire plot, double-click the outside margin of
the plot. This launches Graph Options but contains tabs that relate to the
whole wallplot. You can define margin sizes, grid use and spacing,

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default fonts, line styles, and output Datum. You can display a wallplot
relative to any defined wellpath datum.

Plot Components & Live Data

Similar to the Live Graphs, all graphics/data boxes in an open wallplot
display the data currently active in COMPASS. As the data changes,
these elements are updated. For example, if you select Project Ahead in
the Survey Editor, the project-ahead sections display on any 3D, Plan,
or Vertical Section graph in the wallplot. Also, if a Plan is open, the
planned trajectory is displayed and the section boundaries of these are
toggled on in Graphic Options. Similarly, data boxes present data
relative to the currently active wellpath.

Composer Toolbar

You use the toolbar to access common wallplot tools. Depending on

whether a graph or data box is selected, some of the icons are disabled.
For example, you cannot use the data reader unless you have selected a
graph from which to read data.

Icon Description

Create new template from scratch

Open an existing template file. Use the drop down arrow to

open template from recent selection list

Save the open template to file

Save the open template with the different file name (save
as)

Frames Only—Show only the outline of each component

without the detail, the currently selected component is
shown in full. This feature enables you to quickly refresh
the plot.

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Icon Description

Graph Setup—Displays the setup option for the current

graph. If no graph is selected the base chart options are
displayed (e.g. margins, paper size etc.)

Add/Edit Lines—You use the to add or edit lines or a

graphic component like a section or plan view.

Read Lines from a DXF file—You can import a DXF

(Drawing Exchange Format) file into the Wall Plot
Conductor.

Draw Arrows—Each component can be associated with one

arrow. You can use the arrow to point to a feature on
another component.

Screen Reader—The screen reader displays a cross-hair

cursor that you use to determine the co-ordinates of any
point on a chart. To determine the distance between any
two points, click the left mouse button to set the start point,
move the cursor, then click the left mouse button again to
set the end point. When appropriate, polar co-ordinates are
displayed. For example, a section view shows distance and
inclination while a plan view shows distance and bearing
from local north.

Data Reader—The data reader display the values of points

on the data line. For example, on a section and plan views,
the data reader displays MD, TVD, Inclination, Azimuth,
N/S and E/W for each data point.

Bring to Front / Drop to Back—Use these icons to change

the component order and place the selected object on top of
other objects. Items earlier in the component list take
higher precedence over items lower in the list. When two
graphs are marked as opaque the top component overwrites
the bottom component.

Re-scale Axis—This provides an expanding box with

which you select a portion of the graph. The expanding box
can be anchored at the centre or at a corner.

• To anchor the box at the centre press and hold down

the left mouse button then move the mouse to change
the box size.

• To anchor the box at a corner press and hold down the

right mouse button. As the box expands or contracts it
retains the height to width ratio of the original graph.
To return to the original size, click once without
dragging.

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Icon Description

Edit Data Labels—When data labels such as MDs or

Inclinations are added to a plot, labels can overlap. You use
Edit Data Labels to adjust the location of a label with the
mouse or select Hide to make the label invisible. You can
make the program automatically remove all overwriting
labels by clicking Auto. You can restore hidden or moved
labels to their original state by clicking Restore or Restore
All.

Zoom in—Zoom in (left mouse button) and zoom out (right

mouse button). While the view is magnified, you can re-
centre the plot on the current cursor position by clicking the
left mouse button.

Zoom out—Zoom out to restore to full size.

Offset Wells—Same as the Live Graphs, a wallplot can

display trajectories for a number of selected offset wells.

Alignment Toolbar

The alignment toolbar enables you to arrange the layout of several plot
components relative to each other. It is necessary to hold the CTRL
button, and click on more than one component to organise a group of
components for alignment. Wallplot components can be aligned
vertically and horizontally. They can also be spaced vertically or
horizontally to remove any gaps or overlaps between them.

Commonly Used and Under Appreciated Features

There are numerous options and tools available in graphic and data
boxes for a wallplot. Common features in the WallPlot Composer are

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Chapter 10: Wallplot Composer

available that can be used for all plots. There are also a number various
features of which not everyone is aware.

This section highlights the most commonly used Wallplot Composer

features.

Plotters
Different plotters, printers, and page sizes require different line styles
and font sizes to highlight features of the wallplot. A common problem
is that the line thickness, style, or font for one plotter may not work on
another. This requires adjustment of the wallplot to suit a particular
output device. For this reason, you may want to save wallplot templates
referenced to particular output devices.

Options Tab
Most common features are available from the Options Tab in Graph
Options. Just like Live Graphs, Options enable you to display casings,
formations, annotations, targets, and the error ellipse. Labels for these
objects can be turned off separately to avoid cluttering the plot.
Different types of graphs presents variations in the options available.
For example, the Plan View graph enables you to fill target shapes.

Scale Options
Users in different locations require different scales and units to construct
a wallplot. The COMPASS wallplot composer is constructed to handle

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all types of API and Metric scales. Each graph has a Scales tab located
in Graphic Options. Here is a description of the settings available:

• Always Use Exact Scales. As you resize a graph, COMPASS

changes the scales to ordinals of 1, 2, and 5. The scales
increment as follows: 1, 2, 5, 10, 20, 50, 100, 200, 500 etc.
• Auto Scale. With this checked, COMPASS changes the scale to
fill the graph area with the plot details. This can be used in
conjunction with the Always Use Exact Scales option described
above.
• Fixed Scale. This enables you to specify any scale.
• Fixed Range. This enables you to specify the X and Y axis range.
Note: Ensure you deselect Always Use Exact Scales before
selecting Fixed Range.
• Resize Graph. This option enables you to specify both a range
and scale and resizes the window area of the plot to fit. If the
requested area does not fit within the page the scale stops at the
page margins.With Resize Graph selected, you cannot resize the
graph using the mouse, you can only move the graph.

Scale Origin Options

Fixed X Origin. The X axis value on the left side of the graph.

Fixed Y Origin. The Y axis value on the top of the graph.

With fixed origin scales turned on using Resize Graph you can position
the scales anywhere within the range. You can click Top, Bottom, Left,
and Right to fix the axes at the respective boundary.

Axis Label Options

Use Metric Paper. Scales, grids, and axes are converted for centimetre
paper.

Axis Label Rotation. The orientation of X and Y axis labels can be

changed to fit the tick mark numbers to the space available. A positive

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Chapter 10: Wallplot Composer

angle is anti-clockwise from horizontal. e.g. Use a rotation angle of 90

degrees to tilt the Y axis labels in line with the axis text.

Bitmaps/Metafiles
You can add bitmaps to a wallplot as discrete components. This feature
is commonly used to add logos, graphic headers, pictures, or diagrams
to a plot. To add a bitmap, use Composer to add it to the object list, then
use Conductor to move and resize it to the desired location. Double-
click the bitmap object to display its Graph Options. You can select the
bitmap file location.

You can select two special types of bitmaps in the Composer list:

• Company is the bitmap defined within Company Setup.

• User is the bitmap defined within the User Setup dialogue accessed
from the Utilities menu.
Because these logos are defined by the data, they automatically appear
when a template is opened which includes them. Simple Bitmap entries
in the wallplot do not automatically appear but require you to re-confirm
the file in Graph Options before it is displayed. The file location is
retained.

Text Boxes
A Text Box is a frame for displaying data-driven text or free text. Text
boxes typically appear as part of the wallplot or as message or label
boxes superimposed on top of a graph. You can superimpose a text or
label box by clicking the Bring to Top toolbar icon.

The objects available in the Composer list contain a number of Data

driven text boxes. These text boxes behave the same as a free text box
except that the contents are determined by the active wellpath. The
actual text is presented in Graph Options. You can convert it to free text
by clicking Convert to Free Text.

Font Sizes & Types

You can change the character font for the following:

• Axis Labels —The name of each axis.

• Tick Labels —The values marked along each axis.
• Data Labels —Information along the data line or wellpath.
You can set the consistency of fonts in other text boxes using the Global
toggle box.

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Background Colour and Border

You can define background colour on any data box or North arrow box
using Graph Options. Commonly used background colours include light
grey and light yellow but any colour can be used. The background is
only displayed if the object is set to Opaque in the toggle box located on
the tab marked General. You can display a black boundary line around
the plot component by setting the Border toggle on. This feature is
useful when overlying components.

Label Orientation
You can use labels to highlight different wells, MDs, TVDs, or
Inclinations. In Graphic Options, on the Labels tab is an orientation area
that you can use to adjust how labels display:

You can set label orientation and offset to automatic so that labels are
perpendicular to the wellpath direction and as the wellpath changes the
labels remain right side up. Alternatively, the label orientation can be
user-defined so the direction of all labels is constant, 0.0 being
horizontal. Rotation is anti-clockwise so typing 180 inverts the text.

Auto offset keeps the label one character left and up from the data point.
You can offset the text labels by an X and Y offset from the data point.
The units are characters.

You can justify labels and join text to the data-point at the left, centre or
right side.

Moving Labels

When data labels such as MDs, TVDs, or Inclinations are added to a

plot, some labels can be overwritten. Select Edit Data Labels to adjust
the location of a label with the mouse or make the label invisible by
selecting Hide. You can let the program automatically remove all

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Chapter 10: Wallplot Composer

overwriting labels by clicking Auto. You can restore hidden or moved

labels to their original state by clicking Restore or Restore All.

To edit a single label:

1 Move the label locator until the cross hair falls on the label you
want to move.
2 Click the left mouse button to select and change the current label.
3 Depress the left mouse button and drag the label then click the right
mouse button to release the label.
4 To rotate the labels, type an orientation or click the up or down
arrow buttons.

NOTE:

To select another label highlight the label in the list, you move to
the data point itself and not the label to highlight it.

Grids
Compass enables different types of grids to be present on a graph:

• Normal - grid that the grid lines covers the entire graph area.
• Axis band - draws a grid from the scale axis to the principal line and
the extra width.
• Full band - which only draws a grid in the area that is the width
from the principal line.
Note: Band Grid Width is the distance in real units (ft/m) to draw the
grid from the line.

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The following graphic displays a custom wallplot that displays both

Axis and Full band grids:

2000

South(-)/North(+) [1000ft/in]
Plan View displaying ‘Full’ band grid drawn
1000 250ft left/right of planned sidetrack. Also
1000 displays target (T20) with ‘fill’ and azimuth

100°
95°

95°

105°
labels.

108°
90°
85°
80°°
T20a

750°°
7650
6
2000
T20 (drilling)
0
0 1000 2000 3000 4000 5000
West(-)/East(+) [1000ft/in]
3000
True Vertical Depth [1000ft/in]

LEGEND Legend box displaying reverse text colours

A1 (A1-S0)
A1-S2
4000 A1-S2P1
°
25
35 °
30

40 °
°
45°
50°
55°
60°
65°

Vertical Section View displaying ‘Axis’

70°
75°

79°
5000
band grid drawn below the planned

70°
65°
T20a sidetrack. Also displays horizontal section

61°
boundaries of the plan and inclination
6000 T20 (drilling) labels.

7000

8000
0 500 1000 1500 2000 2500 3000
Vertical Section at 48.50° [500ft/in]

Plan: A1-S2P1 (A1/A1-S2)

Created By: Aberdeen Drilling Support Date: 07/08/2000
Checked: ____________________ Date: __________
Reviewed: ____________________ Date: __________
Approved: ____________________ Date: __________

Datums
Like all other forms of output from COMPASS, the Wallplot Composer
can output relative to any available wellpath datum. This is important if
a production engineer, petrophysicist, geologist, or geophysicist looks at
the plot and needs to reference to their own datum, typically not the
drilling datum. To change the datum, double-click the margin area of the
wallplot in the Conductor to launch Graphic Options. Use the Datum tab
to set the datum. If the desired datum is not present, you must create it
using the Site Datum Editor.

Wall Plot Composer Files

You can save Plots as either Template files (.GTF) or Plot files (.GPF).
A Template file (.GTF) saves the layout and settings for the plot but
does not remember which wellpath and offset wells were used. A
template also does not remember which labels have been edited.

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Chapter 10: Wallplot Composer

A Plot file (.GPF) remembers which wells were used when it was
created and any labels that may have been edited. When a Plot file
(.GPF) is opened, a check is done to see if the correct Wellpath, Plan, or
Survey is open. If it isn’t, a warning appears. The correct wellpath does
not automatically load, you must load it manually. Note that offset wells
are automatically loaded.

Click Save As toolbar icon to select the type of file to save, either a
Template file or Plot file.

Print Preview
Experienced wallplot constructors know that outputting a flawless
perfectly drawn wallplot involves a lot of time and effort to have
everything sized and spaced just right. It is also a case of having
everything configured for the particular plot device. With a template all
this is saved and remembered, but before this is done, the template must
be tested against hardcopy. To avoid a lot of time spent waiting for
hardcopy plots to print, there is a Print Preview tool available under the
File menu whenever a wallplot or live graph is open. This enables you
to see exactly what the plot will look like on hardcopy.

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 References

References

Brooks, A.G. and Wilson, H., An Improved Method for Computing

Wellbore Position Uncertainty and its Application to Collision and
EUROPEC, Milan, 22-24 Oct. 1996.

DuBrule, O. and Nelson, P.H., Evaluation of Directional Survey

Errors at Prudhoe Bay. SPE 15462, 1986 ACTE, New Orleans, Oct
5-8.

Harvey, R.P., Walstrom, J.E. and Eddy, H.D., A Mathematical

Analysis of Errors in Directional Survey Calculations, SPE 3718,
JPT, pp. 1368-1374, Nov. 1971.

McClendon, R.T. and Anders, E.O., Directional Drilling Using the

Catenary Method, SPE/IADC 13478, 1985 SPE/IADC Drilling
Conference, New Orleans, Mar 6-8.

Thorogood, J.L., Instrument Performance Models and their

Application to Directional Survey Operations, SPE 18051, 1988
ATCE, Houston, Oct 2-5.

Thorogood, J.L. and Sawaryn, S.J. The Travelling Cylinder

Diagram: A Practical Tool for Collision Avoidance, SPE 19989,
SPEDE pp. 31-36, Mar 1991.

Walstrom, J.E., Brown, A.A. and Harvey, R.P., An Analysis of

Uncertainty in Directional Surveying, JPT, pp. 515-523, April
1969.

Walstrom, J.E., Harvey R.P. and Eddy, H.D., A Comparison of

Various Directional Survey Models and an Approach to Model
Error Analysis, SPE 3379, SPE 46th Annual Meeting, New
Orleans, Oct 3-6, 1971.

Williamson, H.S., Accuracy Prediction for Directional MWD, SPE

56702, 1999 ACTE, Houston, Oct. 3-6.

Wolff, C.J.M. and deWardt, J.P., Borehole Positional Uncertainty -

Analysis of Measuring Methods and Derivation of Systematic
Error Model, JPT pp.2339-2350, Dec. 1981.

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