WELL LOGGING TOOLS, FUNCTIONS

& APPLICATIONS
PRESENTATION ON WELL
LOGGING
PRESENTED BY

PREM KUMAR CHAWLA

Dy. General Manager
(W)
 TYPES OF WELL LOGGING UNITS/SERVICES
 Open hole Logging : Exploration services
 Cased hole Logging : Completion services
 Production Logging : Diagnostic Services
Important aspects of Logging Operation:
1. Accuracy.
2. Correct Depth Correlation.
3. Repeatability
4. Reproducibility
5. Efficiency

WLS, AHMEDABAD 4
 PRODUCTION LOGGING
PURROSE

For Evaluation of Well Performance

&

For Well Problem Analysis

 Why Production Logging ?

● To diagnose the well problems

(mechanical and production)

• To get layer wise production/injection

rates.

• For Reservoir monitoring

 WELL PROBLEM ANALYSIS
The most common problems that can be
detected by Production Looging are
• Channeling of the fluid behind the casing
through inadequate primary cementing
• Casing tubing or packers leak are most
common in the corrosive environment
• Cross flow between two or more zone.
• Thief zone.
 Grease Injection Schematic
Pack Off
Assembly

Dynamic Seal

Return Line
injection Line

Riser Pipe

Grease Drum

Wire Line BOP

 Objectives of Production Logging

• Maximise oil recovery from their reservoirs, extend the life of existing fields
• PLT work is usually to facilitate optimal reservoir management and to diagnose
problems such as :
• a) Not as much oil is being produced as expected.
• b) There is too much water being produced.
• c) There is too much gas being produced.
• d) The well has leaks or may be becoming mechanically unsound.

By diagnosing problems and quantifying multi phase production the client can
make a
• commercial decision of what to do next. Industry is driven by economics, PL info
can make the difference between going ahead with remedial work or even the
development of an entire field
.
 Objectives of Production Logging

• Different tool strings are required to achieve different objectives.

• Fundamentally there are 2 type of production logging strings: Production

and Injection.
In water injection wells fluid identification tools are not required
• When considering which tools to run. Remember it is better to have too
much information than to have too little!. If you have too much
information then ignore the data you do not need
If you have too little then you have a problem!

• Production Profiling
• Injection Profiling
• Water Problems
• Excessive Gas Problems
• Mechanical Problem s
 EVALUATION OF THE WELL
PERFORMANCE
PRODUCING WELL
In the well it is necessary to know—
• Are all the perforated zones contributing?
• Rate at which the fluid is flowing
• What is the gas oil or oil water ratio?
• Type and proportion of the fluid

INJECTION WELL
• Where are the injected fluid going?
• How much in the each zone ?
• Do the down hole injection rates are comparable
with surface rates ?
I. What Is Production Logging?
What Is Production Logging?

Production Logging is the measurement of fluid parameters on a zone-by-

zone basis to yield information about the type and movement of fluids
within and near the well-bore.

What do we measure ?
Fluid Density
Fluid Velocity
Temperature
Pressure in the well-bore
Fluid holdup
PRODUCTION LOGGING STRING
Performance of Logging Services,
1
Ahmedabad
PL Measurements

Production Logging essentially comprises of four major

measurements:
1. Fluid velocity
2. Temperature
3. Pressure
4. Density, Hold up
5. Three, Four Arm OR Multifeeler Caliper
And that is done conventionally by four main sensors:
1. Spinner
2. Resistance Temperature Detectors (RTDs)
3. Pressure Gauges
4. Gradio Manometer
5. Potential Meter
 PRODUCTION LOGGING TOOLS
(Conventional)

• Flow-meter : Measures the fluid flow inside the well-bore.

• Temperature : Measures the temperature in the well and the departure from
the static thermal gradient.
• Density : Measures the density of the fluid present around tool.
• Capacitance : Measures dielectric property / capacitance of fluid.
• Pressure : Measures the total pressure due to well-bore column &
reservoir.
• Gamma Ray : Measures the natural radioactivity present in and around
well-bore.
• CCL : Responds to change in the amount of ferromagnetic
substance around tool i.e. pipe joints and any unconformity
in the pipe around this tool.
 TOOL CONFIGURATION

Selection of Tool configuration

Fluid Type Tool configuration

Monophasic (Oil or Water or Gas) Flowmeter/Temperature/Pressure
GR/CCL

Biphasic ( Oil-Gas or Water- Gas

Flowmeter/Temperature/Pressure
or Water-Oil )
Density /GR/CCL

Triphasic( water, oil and gas ) Flowmeter/Temperature/Pressure

Density / Hold Up/ GR/CCL
 What Is The use Of PL?

• Flow Behind Casing

• Thief zones / cross flow.Water Water
Sand Sand

• Casing Leaks
• Leaking Bridge Plug Cracks Channel

• Monitoring the well /

Reservoir by periodic Oil Oil
Sand Sand

PL surveys

Tubing, Casing, Packer Leaks Channeled Cement

 What Is The use Of PL?

• Water Coning Gas Coning

Well Bore Well Bore

Gas Cap
Gas Coning

Oil Zone

Water Cone
Oil Zone

Water Zone
• Why Water is problem ?
• What makes a Well to flow.
• If bottom hole pressure in the well bore is less
than formation pressure, well will flow.
• If the well starts to produce water the Hydrostatic
pressure of the fluid column will build up and
bottom hole pressure will increase and as a result
flow rate will decrease. This means less oil and
well will die.
.
 Some Basic Concepts

• Both, Pressure and Temperature Increases With

depth.

• Geothermal Gradient = (BHT - Surface Temp)/Depth

Deg F/ 100 m

• TD = T surface + Geothermal Grad*Depth

 Some Basic Concepts

• Pressure @ D = Fluid density (psi/ft) x Depth

•No external pressure applied
•True Vertical Depth
 Some Basic Concepts
(Pressure Gradient)

• Density of water = 1 gm/cc - 1.09 gm/cc

(0.433 psi/ft - 0.47 psi/ft)
0.45 psi/ft
• Density Of Oil = 0.7 gm/cc - 0.9 gm/cc
(0.30 psi/ft - 0.39 psi/ft)
• Density of gas = 0.04 gm/cc - 0.2 gm/cc
(0.017 psi/ft - 0.087 psi/ft)
Conversion : (psi/ft)/0.433 = gm/cc

1 barrel = 42 US gallon; 1 US gallon = 3.785 litres

 Some Basic Concepts

• Density Calculations Using Pressure Readings.

 Some Basic Concepts

• Temp & Press. reduces as fluid moves up in well

• Oil releases gas as it moves up towards the surface so the
gas holdup increases upwards.
• Volume Of Liquid oil is reduced as it reaches surface
• Volume of water remains almost same
• Density of fluid changes as it reaches surface
• Down hole flow rate is different from up-hole flow rate i.e.
water cut is different from water hold up.
 CALIPER
• Used to determine the cross section of the well in
the production interval so as to help in the
interpretation of the continuous flow meter.
• They have three, four or multi arms.
• In the multi feeler caliper have 20,40 or 60 feelers
• It works on the principle of potentiometer
• Are used to detect
1. effect of corrosion
2. casing cracks
3. perforation
4. miscellaneous breaks
 TEMPERATURE
• Oil and water production zone give the
increase in the temperature while gas
production decreases the temperature due to
adiabatic cooling effect.
• Logging speed must be slow to attain the
temp. of the formation.
APPLICATIONS

The applications are varied:

 Identifying fluid entry/exit points – differential temperature
log.
 Fluid Type – Gas or Oil / Water
 Injection Profiling.
 Identify channeling behind casing.
 Casing / tubing leakage.
 Verifying/ identify the fractures.
 Identify acidized zones.
 Locating Cement top (very old usage).
 FLOWING WELL
Temperature

Flowing • In this well the

geothermal gradient
is shown in green.
1
• Fluid enters the well
through the
2 perforations and
continues up the
well
3
• The hotter fluid
Perforated Zone increases the
4 temperature away
from the geothermal
gradient and then
follows as an
asymptote to the
gradient.
GAS FLOW - TEMPERATURE LOG

• Gas expands as
Flowing it enters the
wellbore
Geothermal Gradient
• The expansion
Gas Entry Flowing with is adiabatic
gas entry

• This creates a
Perforations cooling and
hence a lower
temperature
 FLUID DENSITY TOOL

TWO MAJOR TYPES :

A) Nuclear Tool:
B) DIFFERENTIAL PRESSURE TOOL (Gradiomanometer)
• Measures the density of the fluid down hole.

A. NUCLEAR TOOLS
• Principle: Gamma scattering.
• Accuracy : +/- 0.03 g/cc Sensitivity : +/- 0.01 g/cc
 FLUID DENSITY TOOL
• We are measuring the Density of fluid by a
Radioactive technique. Part of the fluid passes
through the tool between a low activity GR
source Am241 and a Scintillation GR detector.
High density fluids absorb more Grays hence
there are low no. of arrival at detectors and
low density fluids absorb less hence there are
higher no. of arrivals.
NUCLEAR FLUID DENSITY TOOL

STRENGTHS
A) Open to the bulk fluid.

B) Very good in G-W

environments.
Collimated Gamma Source

DRAWBACKS

Well Bore Fluid A ) Statistical Variations

B) Sample volume too less.

Collimated Gamma Detector

 FLUID DENSITY TOOL (Gradio manometer)

B. DIFFERENTIAL PRESSURE TOOLS ( GRADIO )

• Principle: The Gradiometer tool uses pressure differential

between two bellows to infer the density of the fluid between
them. The greater the pressure difference between the
bellows ,greater is the fluid density.
• The fluid density measurement helps to know the relative
amounts of water,oil and gas.

• .
 DIFFERENTIAL PRESSURE TOOL

UPPER SENSOR
h
q h’
h f= P/ h

LOWER SENSOR
f = P/ h’
= P/ (h x cos q)

PRESSURE -DENSITY MEASUREMENT PRESSURE -DENSITY MEASUREMENT

IN A VERTICAL WELL IN A DEVIATED WELL
 Differential Pressure Tool vs Nuclear Tool

Gradiomanometer : Suited for vertical and low deviation wells.

Suited for low-med flow rates (frictional drop)
Reflects the density of the full bore flow.
More rugged.

Nuclear Tool: Better device for deviated wells w.r.t Gradiomanometer

Bulk fluid density measurement.
Sample measurement; may not represent the whole fluid
density.
Statistical measurement.
Radiation hazards though minimal.
 HYDROTOOL
HOLD-UP
• In producing wells it is common to encounter two and
even three phase fluids flow in a well. In case of
multiphase flow it is essential to measure the fraction
by volume of two fluids phases present in different
zones
• The fraction of volume of a particular phase present is
called HOLD-UP.
• It measures the Water hold up and enables the
calculation of the gas / oil and water in the three
phase system. It measures the Dielectric constant
 FLUID CAPACITANCE TOOL /WHUT / HYDRO
TOOL
WATER HOLD UP TOOL or simply HYDRO.

Primary Application : To distinguish water from hydrocarbons.

SENSOR : FLUID CAPACITANCE

Principle : Change in Capacitance due to change in Dielectric medium.

Output in frequency form.

.
 WATER HOLD UP

Apparent Water Holdup is defined as:

(100% Oil Reading - Mixture Reading)

Y wa = -------------------------------------------------------

(100% Oil Reading - 100% Water Reading)

Selection of tool type

• Water Hold Up tool

In single phase flow environment it’s not needed; but for

2-phase & 3-phase flows its necessary to run both
WHUT & Density tools.

Best suited for water cut range generally below 40 %

TYPICAL DIELECTRIC CONSTANTS

FLUID TYPE DIELECTRIC CONST.

(AT 20 DEG C)

AIR 1-2

OIL 2-4

FRESH WATER 80
 PRESSURE TOOLS

• It gives continous measurement of Pressure in the

wellbore.

MAJOR TYPES

A) STRAIN PRESSURE TOOL

B) QUARTZ PRESSURE TOOL

 STRAIN PRESSURE TOOL

• Principle : Pressure induced strain in the sensor causes a

change in the electrical resistance.
• Accuracy : +/- 15 psi @ full scale (10,000 psi)
• Resolution : 1 psi

• Strain gauges are less accurate but have a better response

time to changes in pressure and temperature
QUARTZ PRESSURE GAUGE

• Principle : Piezoelectric Effect

• Sensor : Quartz Crystal

• Accurate absolute pressure

measurements and hence used in
pressure build-up analysis.

• New gauges with accuracy of crystal

gauges and response of strain gauges.
 Strain Pressure Tool vs Quartz Pressure Tool

• Strain Pressure Tools :

Multiphase flow conditions
Bottom hole Pressure measurement
Fluid gradient determination

• Quartz Pressure Tools: Reservoir monitoring

Pressure build-up Analysis
 Pressure

Gas

Depth

Oil (0.30 psi/ft - 0.39 psi/ft).

Water = 0.433 psi/ft

FLUID DENSITY FROM PRESSURE GRADIENT In Static Well-bore

 FLOWMETER
• The Flow meter rotation is picked up by flow
meter electronics. When flow meter shaft
rotates we get pulses per provides velocity
and Direction of flow in the well bore.
 FLOW METER
• It measures the velocity of the
fluid which in turn is used in
calculation of the flow rate(bpd)

These are basically two type

Full bore flow meter
Continuous flow meter

• FULL BORE FLOW METER

in full bore it has a case
depending upon the casing size.
Lowering through the tubing its
size is contracted and after the
casing it again re opens there are
four blades in the spinners.
Spinners are turbine flowmeters
 FLOWMETER SENSOR

Measurement
• Impeller suspended between sapphire jewels
• Magneto-optic pick-up assembly

Response
• Clockwise RPS ( positive ) - Flow from below
• Counter-clockwise RPS (negative) - Flow from above
 Spinner Calibration Plot
RPS (+ve)

Cable Vel
!=0

= 0
Friction !=
Mid-Point 0

Tool Vel Up Tool Vel

Threshold
Fluid Down
Velocity
Fluid
Velocity!=0
Velocity=0
Ideal
FluidFluid
Non-Ideal
RPS (-ve) (µ=0)
(µ!=0)
Qualitative Interpretation
Casing Leakage example (Sonari#1)
Channel Behind Casing
Qualitative Interpretation
Non-performing perforations
Qualitative Interpretation
Fracture identification
Hydro-frac merged log (Before & Aft er)
Qualitative Interpretation
Gas Injection Well
Composite log G#280
Qualitative Interpretation
Gas Injection Well
Qualitative Interpretation
Gas Injection Well
Qualitative Interpretation
Thief Zone (Lim#138) Down Pass
Qualitative Interpretation Casing
Channel from below
Qualitative Interpretation
Channeling to above (injection well)
 TELEMETRY
• Telemetry is the highly automated
communications process by which
measurements are made and other data
collected at remote or inaccessible points and
transmitted to receiving equipment for
monitoring. The word is derived from Greek
roots: tele = remote, and metron = measure