Directional and
Horizontal Drilling
2024
Outline
Lifecycle of the well
Aim of directional and horizontal drilling ?
What are their benefits ?
Basic trajectory design
Deflection method
LWD/MWD
Aim of directional and horizontal drilling ?
Directional drilling
Wells are drilled directionally for several purposes:
•Increasing the exposed section length through the reservoir by drilling
through the reservoir at an angle.
•Drilling into the reservoir where vertical access is difficult or not possible.
For instance an oilfield under a town, under a lake, or underneath a
difficult-to-drill formation.
•Allowing more wellheads to be grouped together on one surface location
can allow fewer rig moves, less surface area disturbance, and make it
easier and cheaper to complete and produce the wells. For instance, on
an oil platform or jacket offshore, 40 or more wells can be grouped
together. The wells will fan out from the platform into the reservoir(s)
below. This concept is being applied to land wells, allowing multiple
subsurface locations to be reached from one pad, reducing costs.
•Drilling along the underside of a reservoir-constraining fault allows
multiple productive sands to be completed at the highest stratigraphic
points.
•Drilling a "relief well" to relieve the pressure of a well producing without
restraint (a "blowout"). In this scenario, another well could be drilled
starting at a safe distance away from the blowout, but intersecting the
troubled wellbore. Then, heavy fluid (kill fluid) is pumped into the relief
wellbore to suppress the high pressure in the original wellbore causing
the blowout.
Horizontal drilling
Horizontal drilling is the
process of drilling a well
from the surface to a
subsurface location just
above the target oil or
gas reservoir called the
“kickoff point”, then
deviating the well bore
from the vertical plane
around a curve to
intersect the reservoir at
the “entry point” with a
near-horizontal
inclination, ...
Well profiles
Why ???
Directional Wells
APPLICATIONS of DIRECTIONAL DRILLING
• Shoreline Drilling
• Inaccessible Locations
APPLICATIONS of DIRECTIONAL DRILLING
• Multiple Wells from Offshore
Platform
• Relief Wells
APPLICATIONS of DIRECTIONAL DRILLING
• Sidetracking
Original Well
Path Sidetrac
Corre k Original
cted Well Path Sidetrack
Well Original Well
Path Path
• Multi-Lateral Wells
Types of Directional Well Profile
Build and hold profile (Type 1)
It is the most common and simplest.
The well is vertical until the KOP
where it is kicked off and an angle is
built. When the desired inclination is
reached, the well path is kept
tangent or straight until the target is.
Type I Directional Well
Types of Directional Well Profile
Deep build/kick-off (J Type)
These types of well profiles are
normally used in Appraisal wells
to assess the extent of a newly
discovered reservoir. It is a type
of wellbore drilled when there is
a hindrance, such as a salt
dome, or when the well has to
be side-tracked The well is drilled
vertically to a deep KOP and
Type I Directional Well
then inclination is built quickly to
Types of Directional Well Profile
Deep build/kick-off (J Type)
These types of well profiles are
normally used in Appraisal wells
to assess the extent of a newly
discovered reservoir. It is a type
of wellbore drilled when there is
a hindrance, such as a salt
dome, or when the well has to
be side-tracked The well is drilled
vertically to a deep KOP and
then inclination is built quickly to Type III Directional Well
Types of Directional Well Profile
Planning & Calculating The Trajectory
Nowadays there are software programs that work on these
mathematical equations to solve them and give you the results
(Compass and Well cat) but it is good to know what you have
and what you can get from it
Loads on Tubulars
Loads on Tubulars
Burst Loads
Collapse Loads
Tensile Loads
Service Loads
Yield Strength
An introduction to Torque and Drag
Torque and drag are the results of friction caused by a moving
pipe inside the wellbore: torque occurs when rotating the pipe
along the wellbore and drag occurs when moving the pipe
Torque:
Torque is the force required to turn the drill string. In figures below
you see Surface torque and Downhole torque.
Drag:
Drag is the increase in string weight when pulling out of the hole
or the reduction in string weight while tripping in the hole. Below
you see Drag vector and calculation of it.
Basic parts
BASIC TERMINOLOGY
TVD: This is the vertical distance from the wellhead to a
point in the well path. This quantity is calculated from the
directional survey data. Note that a measured depth, due
to the wellbore curvature, is always greater than the
corresponding true vertical depth.
Well Inclination
-The well inclination is the angle by which the wellbore deviates
from the vertical.
Well Azimuth
Well Azimuth
Well Azimuth
215
DEFINITIONS - Build Curve
Generally
Long: < 8deg/100ft
Medium: >8 <30deg/100ft
Short: >30deg/100ft
(variations)
Survey Definitions
Common terminology for a RKB
directional profile
KOP
Build Section
EOB or EOC
TVD, ft
Tangent or Hold
Drop
Section
Departure, ft
Deflection Tools
There are a number of tools and techniques which can be used
to change the direction in which a bit will drill. These tools and
techniques can be used to change the inclination or the
azimuthal direction of the wellbore or both. All of these tools and
techniques work on one of two basic principles. The first principle
is to introduce a bit tilt angle into the axis of the BHA just above
the bit and the second is to introduce a side force to the bit .
The introduction of a tilt angle or side force to the bit will result in
the bit drilling off at an angle to the current trajectory. The major
tools currently used for this purpose are
Whipstocks
Rotary BHA Stabilizers
Bent Sub and Positive Displacement Motor
Downhole Mud Motor
Mud Motor Hydraulics
Mud Motor Operations & Limitations
Methods of Deflecting a Wellbore
Any number of directional tools can be used to deflect a wellbore
or make the wellbore go where we want it to go.
Whipstocks
Rotary BHA
Rotary BHA with adjustable stabilizer
Motor
Steerable motor
Rotary steerable assembly
DIRECTIONAL DRILLING
- Tools and Techniques
Whipstock
The main deflection tool 1930 – 1950.
Back in fashion with side-tracking from
existing wells (e.g. high H2O) and
multi-lateral drilling
• Standard removable whipstock
• Permanent casing whipstock
History - Open Hole Whip-stocking
• Used in medium to hard formations
• Bit, NB Stab. pinned to whip and conveyed to bottom
• Tool Face oriented
• Whip is wedged on bottom and pin sheared
• Undersized pilot hole is drilled
• Only one joint drilled before POOH the BHA
• Pilot hole opened up and process repeated
Methods of Deflection
The primary use of a Starting
whipstock today is in mill
sidetracking out of casing
Shear bolt
Shear
bolt
slips
Slips
Bottom
trip
Bottom Trip
Bridge
plug
Bridge Plug
Methods of Deflection
starter
Starter Mill
Two trips are Watermilon
required to mill
Watermelon Mill
sidetrack the
wellbore
Window Mill
Window
mill
History - Jetting
• Used in soft formations
• One large bit nozzle oriented to the desired direction
• Near Bit Stabiliser and limber assembly
• Wash a “pocket” in the formation
• Spud and rotate, wash, until angle is built
• Continue building with rotary BHA
• Azimuth corrections more difficult with > inclination
Jetting (badgering)
Developed in the mid 1950s and superseded whipstocks, still
used in the following situations :
• Soft formations to be eroded (80 ft/hr)
• Adequate rig hydraulic horsepower (500 ft/sec)
ADVANTAGES:-
• simple and cheap, no special equipment
• dogleg severity controlled from surface
• survey tool not far from the bit
• orientation of tool face is easy
• same assembly can be used for drilling
Methods of Deflection
Rotary BHA
The rotary BHA consists of a bit, drill collars, stabilizers, reamers
run below the drill pipe.
Deviation Drilling with
Bottom Hole Assemblies
Rotary motor
Adjustable Bend Housing
Works on offset pin and box concept
Typically adjust from 1 to 3 degrees
Four main Components: Offset Housing,
Splined Mandrel, Stator Adapter Housing,
and Adjusting Ring
Adjustable Bend Housing
Methods of Deflection
Typical steerable motor configuration
Bent Housing for Changing Direction
When Sliding the Drillstring
Stabilizers Define Directional Tendency
When Rotating the Drillstring
Methods of Deflection
Steerable motor in the slide & rotate mode
Sliding Rotating
Methods of Deflection
Rotary steerable
Steerable without sliding (100% rotation)
Can change both inclination and direction
RSS
A rotary steerable system (RSS) is a form of drilling technology used
in directional drilling. It employs the use of specialized downhole
equipment to replace conventional directional tools such as mud motors.
They are generally programmed by the measurement while drilling (MWD)
engineer or directional driller who transmits commands using surface
equipment (typically using either pressure fluctuations in the mud column
or variations in the drill string rotation) which the tool responds to, and
gradually steers into the desired direction. In other words, a tool designed
to drill directionally with continuous rotation from the surface, eliminating
the need to "slide" a mud motor.
Measurement while drilling (MWD)
.
.
.
.
.
.
.
.
MUD PULSE TELEMETRY
Positive Mud Pulse Telemetry
MUD PULSE TELEMETRY
Negative Mud Pulse Telemetry
MUD PULSE TELEMETRY
Continuous Wave Telemetry
.
Continuous wave telemetry uses a rotary valve or “mud siren” with a slotted
rotor and stator which restricts the mud flow in such a way as to generate a
modulating positive pressure wave which travels to the surface and is
detected at the standpipe.
This is a more sophisticated telemetry system and offers a higher data rate
than the previous two mud pulse methods.
Continuous Wave Telemetry
MUD PULSE TELEMETRY
Continuous Wave Telemetry
.
Continuous Wave Telemetry
MUD PULSE TELEMETRY
POWER SOURCES
. Tool works in two situations :
The MWD
(a) When the circulation is ON
(b) When there is no circulation, i.e. while tripping when the pump is
in OFF condition.
Also, once lowered, the MWD tool is not retrieved back to surface
unless there is some kind of problem with tool.
Thus to continuously provide power to the tool, we require a power
source.
The power source can be :
(a) Batteries(Lithium Battery, usually 24 V)
(b) Turbine Alternators
TRANSMISSION SYSTEM
MWD SENSORS
An MWD tool is equipped with the combination of
following sensors depending upon the requirement :
Directional Sensor
Gamma ray Sensor
Temperature Sensor
Downhole WOB/ Torque Sensor
Turbine RPM Sensor
Logs
Well logging is an evaluation method in which a logging crew lowers a
special tool, into the well and then pulls it back up.
Gama ray log
Well drilling and for other related purposes. Different
types of rock emit different amounts and different spectra
of natural gamma radiation. In particular, shales usually
emit more gamma rays than other sedimentary rocks,
such as sandstone, gypsum, salt, coal, dolomite,
or limestone because radioactive potassium is a common
component in their clay content, and because the cation-
exchange capacity of clay causes them to
absorb uranium and thorium. This difference in
radioactivity between shales and sandstones/carbonate
rocks allows the gamma ray tool to distinguish between
shales and non-shales. But it cannot distinguish between
carbonates and sandstone as they both have similar
deflections on the gamma ray log. Thus gamma ray logs
cannot be said to make good lithological logs by
themselves, but in practice, gamma ray logs are
compared side-by-side with stratigraphic logs.
Resistivity log
Resistivity logging is a method of well
logging that works by characterizing
the rock or sediment in a borehole by
measuring its electrical resistivity.
Resistivity is a fundamental material
property which represents how
strongly a material opposes the flow
of electric current. In these logs,
resistivity is measured using four
electrical probes to eliminate the
resistance of the contact leads. The
log must run in holes containing
electrically conductive mud or water,
i.e., with enough ions present in the
drilling fluid.
Resistivity log
Thank You
Don’t forget to follow us on:
/Uptainers
