Wireline Logging Full Report

8/10/2019 Wireline Logging Full Report

http://slidepdf.com/reader/full/wireline-logging-full-report 1/38

1. INTRODUCTION

When deciding whether to develop a field, a company must estimate how much oil and gas will be recoveredand how easily they will be produced. Although the volume of oil and gas in place can be estimated from the

volume of the reservoir, its porosity, and the amount of oil or gas in the pore spaces, only a proportion of

this amount will be recovered. This proportion is the recovery factor, and is determined by various factors

such as reservoir dimensions, pressure, the nature of the hydrocarbon, and the development plan.

The advantages of wireline logging are considerable. It allows the acquisition of valuable data at a fast rate

and over a wide range of depths. This allows fast and accurate decisions to be made regarding drilling, based

on the information obtained. Understanding the physical properties of an oil well is critical to properly

managing it over its lifetime. Wireline logging makes that possible.

In wireline logging time is a critical factor. The cost of running operations on an offshore drilling rig is very

high: drilling a well might cost $1 –2 million per day of opera ons. In such opera ons, down me and logging-

equipment failures are expensive. Well logging equipment costs are only a small part of the cost of drilling

operations and generally a very small fraction of the hydrocarbon production costs. Modifications that

improve the accuracy of logging without compromising reliability of the data are welcome in the industry

even if they raise the cost. As a result, many techniques have been used for well logging. Several techniques

are discussed in this report.

Well loggers use combinations of both radiation-based and non-radiation-based tools (called nuclear andnonnuclear in this field) to examine the earth formations surrounding the well and sensors to detect the

media’s response to interrogation tools. An analyst examines detector logs to look for some or all of the

following parameters of the formation: formation water saturation, porosity, rock characteristics,

carbon/oxygen ratio, and permeability.

Because of the complexity of earth formations, only a combination of all the logs allows the log analyst to

draw accurate conclusions for the formation parameters. For example, combining resistivity and nuclear

logs, the log analyst can determine porosity, water content, and density (see fig(1.1)).



1.1 Definition of wire line logging

Well logs result from a probe lowered into the borehole at the end of an insulated cable. The resultingmeasurements are recorded graphically or digitally as a function of depth. These records are known as

geophysical well logs, petrophysical logs, or more commonly well logs, or simply logs.

Wireline logging has a history that goes back just over 80 years to September 5th, 1927 when two brothers, Conrad and Marcel Schlumberger, ran what is considered to be the very first wireline log at

the Pechelbronn Oil Company oil field in France.

Their experimental logging attempt was a success and the brothers called their new technique an

electric survey. A few years later in the early 1930s in the USA the term "well log" was being used.

Wireline logging is so called because the logging tool is lowered through the oil well or borehole on

the end of a wireline.

1.2 Main principle:

The sensing element is fixed on the sonde, this element gathers information from the well and then entered

to a signal conditioning element to make the signal ready for transmission.The data from the sonde are

transmitted up the cable to instruments in the logging truck where they are recorded (field print). The data

are also processed later, and a cleaner log (final print) is made. The logging data are digitised (if was not

digital already), recorded on the hard drive, and sent to a logging company office (email), otherwise put on a

server or the Internet.

1.3 How to make a wireline well log:

To make a wireline well log after the well (a section) is drilled (and before setting casing), the hole is first

cleaned by the circulating drilling mud and then the drilling equipment is pulled from the well.

Then a sonde (probe) is lowered down the well (which is still filled with the drilling mud) on a logging cable.The logging cable is an armoured cable with steel cables surrounding conductor cables in insulation. It is

reeled out from the drum in the back of a logging truck.



1.4 Sonde

The sonde or tool is a cylinder, commonly 27 to 60 (8 to 19 m) long and some mes up to 90

(27.5m) long, 3 to 4 in (8 to10 cm) in diameter and is filled with instruments (electric, nuclear or

acoustic transmitters, receivers and amplifiers).

Several instrument packages such as formation density, neutron porosity and gamma ray can be

screwed together to form the sonde.

The sonde has either one expandable arm or bow spring that puts the sensors in contact with the

well walls or three expandable arms or bow springs that centers the sonde in the well.

As the sonde is run back up the well, it remotely (with respect to a guy in the truck) senses the

electrical, acoustical, and/or radioactive properties of the rocks and their fluids and sometimes the

geometry of the wellbore.

In a directional well with a high deviation or a horizontal hole, the sonde must be pushed down the

well with tubing or the drillstring. One trip down and up with a sonde is called a run.



1.4.1 Main components of the sonde:

Sonde on a wireline

a) cross section of the

armoured cable,

b) Sondes with arms,

c) Sondes with bow spring(s)



2. SPONTANEOUS POTENTIAL LOG

The spontaneous potential log, commonly called the self-potential log or SP log, is a measurement

taken by oil industry well loggers to characterise rock formation properties. The log works bymeasuring small electric potentials (measured in millivolts) between depths in the borehole and a

grounded voltage at the surface.

It’s one of the first log measurements made. It was discovered as a potential that effected old electric

logs .It has been in use for over the past 50 years.

The change in voltage through the well bore is caused by a buildup of charge on the well bore walls.

Clays and shales (which are composed predominantly of clays) will generate one charge and

permeable formations such as sandstone will generate an opposite one. This build up of charge is, in

turn, caused by differences in the salt content of the well bore fluid (drilling mud) and the formation

water (connate water ). The potential opposite shales is called the baseline, and typically shifts only

slowly over the depth of the borehole. Whether the mud contains more or less salt than the connatewater will determine the which way the SP curve will deflect opposite a permeable formation. The

amplitudes of the line made by the changing SP will vary from formation to formation and will not

give a definitive answer to how permeable or the porosity of the formation that it is logging.

2.1 APPLICATIONS

The SP tool is one of the simplest tools and is generally run as standard when logging a hole, along

with the gamma ray. SP data can be used to find:

Correlation from well to well . Depth reference for all logging runs .

Detecting permeable beds (Where the permeable formations are ).

The boundaries of these formations Detecting bed boundaries .

Rw determination and the values for the formation-water resistivity .

The SP curve can be influenced by various factors both in the formation and introduced into the

wellbore by the drilling process. These factors can cause the SP curve to be muted or even inverted

depending on the situation.

Bed thickness (h), and true resistivity (Rt) of the permeable bed.

Invaded resistivity (Rxo) and the diameter of invasion (di)

Ratio of mud filtrate to formation water salinities - Rmf/Rw

Neighboring shale resistivity (Rs)

Hole diameter (dh)

Mud resistivity (Rm)

http://en.wikipedia.org/wiki/Oil_industry

http://en.wikipedia.org/wiki/Well_logging

http://en.wikipedia.org/wiki/Drilling_mud

http://en.wikipedia.org/wiki/Connate_water

http://en.wikipedia.org/wiki/Connate_water

http://en.wikipedia.org/wiki/Drilling_mud

http://en.wikipedia.org/wiki/Well_logging

http://en.wikipedia.org/wiki/Oil_industry



There are many SP correction charts available although no one chart is able to include all the

possible variables in making the necessary corrections.

Fig(2.1): SP Correction Chart



The drilling mud salinity will affect the strength of the electromotive forces (EMF) which give the

SP deflections. If the salinity of the mud is similar to the formation water then the SP curve may give

little or no response opposite a permeable formation; if the mud is more saline, then the curve has a

positive voltage with respect to the baseline opposite permeable formations; if it is less, the voltage

deflection is negative. In rare cases the baseline of the SP can shift suddenly if the salinity of the mud

changes part way down hole.

Mud invasion into the permeable formation can cause the deflections in the SP curve to be rounded

off and to reduce the amplitude of thin beds. A larger wellbore will cause, like a mud filtrate

invasion, the deflections on the SP curve to be rounded off and decrease the amplitude opposite thin

beds, while a smaller diameter wellbore has the opposite effect.



Illustration of the principle of the spontaneous potential (SP) log. A natural potential is measured

between an electrode in the well and earth at the surface (redrawn from Rider, 1996).

The SP electrode is built into different logging tools for example:

Induction log.

Laterolog.

Sonic log.

Sidewall core gun.

Fig(2.2): Borehole mud invasion profile Fig (2.3): The SP measurement

SP results from electric currents flowing in the drilling mud. There are three sources of the

currents, two electrochemical and one electrokinetic. Deflection of SP is caused by the

Electrochemical Ec and Electrokinetic Ek actions:



2.2 Electrochemical Component

Ec = Elj + Em

These two effects are the main components of the SP. They are caused as a result of differing

salinities in the mud filtrate and the formation water.

Elj: "Liquid Junction Potential"

The ions Na+ and Cl- have different nobilities at the junction of the invaded and virgin zones.

The movement of the ions across this boundary generates a current flow and hence a

potential.

If the salinity of the mud in the borehole is weaker or stronger than that of the formation

water the potential generated between the two solutions is known as the Liquid Junction

Potential or Elj. The greater the difference between the salinity of the solutions the greater the

potential.

Fig(2.4): Liquid Junction Effects #1

Fig(2.5): Liquid Junction Effects #2



Em: "Membrane Potential"

Shale’s are permeable to Sodium ions but not to Chlorine ions. Hence there is a movement of

charged particles through the shale creating a current and thus a potential. This is known as

the membrane potential or Em.

Fig (2.6): Membrane Potential SP

2.3 Deflection of the SP curve

The SP measurement is constant but jumps suddenly to another level when crossing the

boundary between two different formations.

When Rmf > Rw The SP deflects to the left (-ve SP) found in permeable formations filled

with formation water ,

When Rmf < Rw The SP deflects to the right (+ve SP) found in permeable formation filled

with formation water ,

There is no deflection in non-permeable or shaly formations.



Fig(2.7): SP Deflection

2.4 CALIBRATION

In the logging unit there is a small battery and a potentiometer in series between the two electrodes.

The logging engineer can adjust the potentiometer so that the SP appears in track 1. Since we need to

remove all extraneous potentials to the membrane potential, the SP needs to be normalised in a

computing centre so that there is no potential (SP=0.0MV) opposite shale beds. This is done

concurrently with the SP drift correction. The absolute difference between shale and sand remains

the same after drift correction. Caution:

Some field engineers in the past varied the potentiometer to correct the drift while logging and

therefore keep the SP on the display track. Recent logging tools record the raw SP on data storage

(i.e. no battery and no potentiometer) and it is sometimes preferable to use this raw SP to perform the

SP correction. An offset can be applied to the raw SP if its values range significantly above zero.



2.5 LIMITATIONS :

Borehole mud must be conductive.

Formation water must be water bearing and conductive.

A sequence of permeable and non-permeable zones must exist.

Small deflection occurs if Rmf=Rw .

Not fully developed in front of thin beds .

2.6 Metallic reaction at measure electrode

This is one of the components that will cause the SP to drift. The SP electrode made of mild

iron will rust and this oxidizing effect of the electrode results in an added electrochemical

potential to the SP measurement. The drift gradually disappears as the electrode becomes

fully oxidized. Because this is an undesirable potential, the drift can be removed by

correcting the SP curve using computer software.

Possible solution to the problem:

The bridle electrode should be made of lead as it incurs less oxidization and

therefore less drift.

Never clean or remove the rust from the SP electrode.

One hour before going down hole, wrap the electrode in a rag soaked in the mud

pit. This will reduce the oxidizing effect down hole .

2.7 Other unwanted SP potentials

Heavy rain:If heavy rain starts during logging, the surface conductivity of the soil will gradually change

and therefore can gradually change the potential between the surface reference and the down

hole electrode and thus contribute to the SP drift.

Noise:Surface noise such as electrical leakages on the rig, welding equipment, weather storms and

lightning strikes will cause the SP to be noisy and at random. No welding should be allowed

during the recording of the SP log.

Logging drum and sheave magnetism:

If part of the logging drum, wire line sheave or measure wheel is magnetized, this will appear

on the SP curve as a short and regular deflections.

Disruptions to the ground reference:

The SP electrode (called the fish) should be placed in an undisturbed position in the mud pit

away from moving mud fluids.

Power lines, electric trains, close radio transmitters and cathodic protection devices all create

currents, which disrupt the ground electrode reference causing a poor, sometimes useless log.

Bimetallism occurs when two different metals are touching surrounded by mud produces a

weak battery.



3. ACOUSTIC LOGGING

3.1 Definition in Geophysics:

A display of travel time of acoustic waves versus depth in a well. The term is commonly used as a synonym

for a sonic log. Some acoustic logs display velocity.

3.2 Formation evaluation:

A record of some acoustic property of the formation or borehole. The term is sometimes used to refer

specifically to the sonic log, in the sense of the formation compressional slowness. However, it may alsorefer to any other sonic measurement, for example shear, flexural and Stoneley slownesses or amplitudes,

or to ultrasonic measurements such as the borehole televiewer and other pulse-echo devices, and even to

noise logs.

3.3 Introduction

The sonic or acoustic log measures the travel time of an elastic wave through the formation. This

information can also be used to derive the velocity of elastic waves through the formation. Its main use is to

provide information to support and calibrate seismic data and to derive the porosity

of a formation. The main uses are:

Provision of a record of “seismic” velocity and travel time throughout a borehole. This information can

be used to calibrate a seismic data set (i.e., tie it in to measured values of seismic velocity).

Provision of “seismic” data for the use in creating synthetic seismograms.

Determination of porosity (together with the FDC and CNL tools).

Stratigraphic correlation.

Identification of lithologies.

Facies recognition.

Fracture identification.

Identification of compaction.

http://www.glossary.oilfield.slb.com/Display.cfm?Term=traveltime

http://www.glossary.oilfield.slb.com/Display.cfm?Term=sonic%20log

http://www.glossary.oilfield.slb.com/Display.cfm?Term=velocity

http://www.glossary.oilfield.slb.com/Display.cfm?Term=formation

http://www.glossary.oilfield.slb.com/Display.cfm?Term=borehole


http://www.glossary.oilfield.slb.com/Display.cfm?Term=sonic%20measurement

http://www.glossary.oilfield.slb.com/Display.cfm?Term=borehole%20televiewer

http://www.glossary.oilfield.slb.com/Display.cfm?Term=pulse%2Decho

http://www.glossary.oilfield.slb.com/Display.cfm?Term=pulse%2Decho

http://www.glossary.oilfield.slb.com/Display.cfm?Term=borehole%20televiewer

http://www.glossary.oilfield.slb.com/Display.cfm?Term=sonic%20measurement


http://www.glossary.oilfield.slb.com/Display.cfm?Term=borehole


http://www.glossary.oilfield.slb.com/Display.cfm?Term=velocity


http://www.glossary.oilfield.slb.com/Display.cfm?Term=traveltime



Identification of over-pressures.

Identification of source rocks.

The tool works at a higher frequency than seismic waves, therefore one must be careful with the direct

comparison and application of sonic log data with seismic data.

3.4 Wave Types

The tool measures the time it takes for a pulse of “sound” (i.e., and elastic wave) to travel from a transmitter

to a receiver, which are both mounted on the tool. The transmitted pulse is very short and of high

amplitude. This travels through the rock in various different forms while undergoing dispersion (spreading of

the wave energy in time and space) and attenuation (loss of energy through absorption of energy by the

formations). When the sound energy arrives at the receiver, having passed through the rock, it does so at

different times in the form of different types of wave. This is because the different types of wave travel with

different veloci es in the rock or take different pathways to the receiver. Figure 16.1 shows a typical

received train of waves. The transmitter fires at t = 0. It is not shown in the figure because it is masked from

the received information by switching the receiver off for the short duration during which the pulse is

transmitted. This is done to ensure that the received information is not too complicated, and to protect the

sensitive receiver from the high amplitude pulse. After some time the first type of wave arrives. This is the

compressional or longitudinal or pressure wave (P-wave). It is usually the fastest wave, and has a small

amplitude. The next wave, usually, to arrive is the transverse or shear wave (S- wave). This is slower than the

P-wave, but usually has a higher amplitude. The shear wave cannot propagate in fluids, as fluids do not

behave elastically under shear deformation. These are the most important two waves. After them comeRayleigh waves, Stoneley waves, and mud waves. The first two of these waves are associated with energy

moving along the borehole wall, and the last is a pressure wave that travels through the mud in the

borehole. They can be high amplitude, but always arrive after the main waves have arrived and are usually

masked out of the data. There may also be unwanted Pwaves and S-waves that travel through the body of

the tool, but these are minimized by good tool design by (i) reducing their received amplitude by arranging

damping along the tool, and (ii) delaying their arrival until the P-wave and S-wave have arrived by ensuring

that the pathway along the tool is a long and complex one. The data of interest is the time taken for the P-

wave to travel from the transmitter to the receiver. This is measured by circuitry that starts timing at the

pulse transmission and has a threshold on the receiver. When the first P-wave arrival appears the threshold

is exceeded and the timer stops. Clearly the threshold needs to be high enough so that random noise in the

signal dies not trigger the circuit, but low enough to ensure that the P-wave arrival is accurately timed.



Fig (3.1) The geophysical wavetrain received by a sonic log.

There are complex tools that make use of both P-waves and S-waves, and some that record the full wavetrain ( full waveform logs). However, for the simple sonic log that we are interested in, only the first arrival of

the P-wave is of interest. The time between the transmission of the pulse and the reception of the first

arrival P-wave is the one-way time between the transmitter and the receiver. If one knows the distance

between the transmitter (Tx) and the receiver (Rx), the velocity of the wave in the formation opposite to the

tool can be found.

In practice the sonic log data is not presented as a travel time, because different tools have different Tx-Rx

spacings, so there would be an ambiguity. Nor is the data presented as a velocity. The data is presented as a

slowness or the travel time per foot traveled through the formation, which is called delta t (t or T), and is

usually measured in s/ft. Hence we can write a conversion equation between velocity and slowness:

where the slowness, t is in microseconds per foot, and the velocity, V is in feet per second.

The velocity of the compressional wave depends upon the elastic properties of the rock (matrix plus fluid),

so the measured slowness varies depending upon the composition and microstructure of the matrix, the

type and distribution of the pore fluid and the porosity of the rock. The velocity of a Pwave in a material is

directly proportional to the strength of the material and inversely proportional to the density of the

material. Hence, the slowness of a P-wave in a material is inversely proportional to the strength of the

material and directly proportional to the density of the material, i.e.;



The strength of a material is defined by two parameters (i) the bulk modulus, and (ii) the shear modulus.

3.5 Reflection and Refraction

The transmi er emits “sound” waves at a frequency of about 20-40 kHz, in short pulses, of which there are

between 10 and 60 per second depending on the tool manufacturer. The energy spreads out in all directions.

Imagine a pulse emanating from a Tx on a sonic tool. It will travel through the drilling mud and encounter

the wall of the borehole. The P-wave travels well through the mud at a relatively slow velocity, Vm, as the

mud has a low density. The S-wave will not travel through liquid mud. At the interface it is both reflected

back into the mud and refracted into the formation. The portion of the Pwave energy that is refracted into

the formation travels at a higher velocity, Vf , because the density of the rock is higher. We can use Snell’s

law to write;

and at the critical angle of refraction, where the refracted wave travels along the borehole wall, R= 90o, so;

Hence, if the velocity of the elastic wave in the formation changes, the critical angle, i, will also change.

The velocity of the refracted wave along the borehole wall remains Vf . Each point reached by the wave acts

as a new source retransmitting waves back into the borehole at velocity Vm.

Fig (3.2) Reflec on andrefraction at the borehole wall



3.6 Sonic Tools

3.6.1 Early Tools

Early tools had one Tx and one Rx. The body of the tool was

made from rubber (low velocity and high attenuation material)

to stop waves travelling preferentially down the tool to the Rx.

There were two main problems with this tool. (i) The measured

travel time was always too long because the time taken for the

elastic waves to pass through the mud was included in the

measurement. The measured time was A+B+C rather than just

B. (ii) The length of the formation through which the elastic

wave traveled (B) was not constant because changes to the

velocity of the wave depending upon the formation altered thecritical refraction angle.

Fig(3.3 ) Early sonic tools.

3.6.2 Dual Receiver Tools

These tools were designed to overcome the problems in the early tools. They use two receivers a few feet

apart, and measure the difference in times of arrival of elastic waves at each Rx from a given pulse from the

Tx . This time is called the sonic interval transit time (t) and is the time taken for the elastic wave to travel

through the interval D (i.e., the distance between the receivers).

The me taken for elas c wave to reach Rx1:TRx1= A+B+C

The time taken for elas c wave to reach Rx2:TRx2 = A+B+D+E

The sonic interval transit time: T = (TRx2 - TRx1) = A+B+D+E – (A+B+C) = D+E-C.

If tool is axial in borehole: C = E, soT = (TRx2 - TRx1) = D

The problem with this arrangement is that if the tool is tilted in the hole, or the hole size changes, we can

see that C E, and the two Rx system fails to work.



Fig (3.4)Dual receiver sonic tools in correct Fig (3.5) Dual receiver sonic tools in incorrect

configuration. configuration.

3.6.3 Borehole Compensated Sonic (BHC) Tool

This tool compensates automatically for problems with tool

misalignment and the varying size of the hole (to some extent) that

were encountered with the dual receiver tools. It has two

transmitters and four receivers, arranged in two dual receiver sets,

but with one set inverted (i.e., in the opposite direction). Each of

the transmitters is pulsed alternately, and t values are measured

from alternate pairs of receivers. These two values of t are then

averaged to compensate for tool misalignment, at to some extent

for changes in the borehole size.

A typical pulse for the BHC is 100 s to 200 s, with a gap of about

50 ms, giving about 20 pulses per second. There are four individual

Tx-Rx readings needed per measurement, so 5 measurements can

be made per second. At a typical logging speed of 1500 m/h (5000

/h), gives one reading per 8 cm (3 inches) of borehole. Several

versions of the BHC are available with different Tx-Rx distances

(3 . and 5 . being typical),and the Rx-Rx distance between Fig(3.6) Borehole compensated sonic tools.



pairs of receivers is usually 2 .

3.6.4 Long Spacing Sonic (LSS) Tool

It was recognized that in some logging conditions a longer Tx-Rx

distance could help. Hence Schlumberger developed the long spacing

sonic (LSS), which has two Tx two feet apart, and two Tx also two feet

apart but separated from the Tx by 8 feet. This tool gives two

readings; a near reading with a 8-10 . spacing, and a far reading with

a 10-12 . spacing.

Fig(3.7) Long spacing sonic tools.

3.7 Calibration

The tool is calibrated inside the borehole opposite beds of pure and known lithology, such as anhydrite (50.0s/ .), salt (66.7s/ .), or inside the casing (57.1s/ft.).

3.8 Depth of Investigation

This is complex and will not be covered in great detail here. In theory, the refracted wave travels along the

borehole wall, and hence the depth of penetra on is small (2.5 to 25 cm). It is independent of Tx- Rx spacing,

but depends upon the wavelength of the elastic wave, with larger wavelengths giving larger penetrations. As

wavelength l = V / f (i.e., velocity divided by frequency), for any given tool frequency, the higher the velocitythe formation has, the larger the wavelength and the deeper the penetration.



3.9 Logging Speed

The typical logging speed for the tool is 5000 /hr (1500 m/hr), although it is occasionally run at

lower speeds to increase the vertical resolution.

The Compensated Sonic Sonde The Long Spaced Compensated Sonic Sonde



4. GAMMA RAY LOG

4.1 Introduction

There are a number of nuclear well logging tools that have been and still are important in the evaluation of

hydrocarbon wells and reservoirs. While the recent interest in logging-while-drilling tools has changed the

emphasis somewhat, interest in nuclear tools has remained as high as, or higher than, ever.

The nuclear tools play roles in the determination of a number of the most important hydrocarbon well

characteristics such as porosity, elemental composition, and whether or not oil or water is present. The

nuclear tools of primary interest use either sources of gamma rays or neutrons.

4.2 Definition:

Is a wireline well log that records the natural radio activity (gamma ray emission) of rocks in the well by a

scintillation crystal in the snode.

4.3 Basic principle:

The Gamma ray tool produces a measurement of the naturally occurring

radiation found in rock formations. The Gamma Log produced by these tools

is commonly used for depth correction, correlation with open hole logs and

identifying low radiation and high radiation lithologies.



4. 4 Types of Gamma probes:

1. Total count probes ( measures the concentration of Gamma rays).

2. Spectral probes ( measures the energy of each gamma ray).

4.5 Method of operation:

Natural gamma-ray tools are designed to measure naturally occurring gamma radiation in the earth

caused by the disintegration due to Potassium, Uranium, and Thorium. Unlike nuclear tools, these

natural gamma ray tools do not emit any radiation.

Natural gamma ray tools employ a radioactive sensor, which is usually a scintillation crystal thatemits a light pulse proportional to the strength of the gamma ray pulse incident on it. This light pulse

is then converted to a current pulse by means of a photo multiplier tube PMT where the current is

amplified about 1x106 times. From the photo multiplier tube, the current pulse goes to the tool's

electronics for further processing and ultimately to the surface system for recording. The data then

can be converted to energy spectra which can be easily read to find information about the well. The

strength of the received gamma rays is dependent on the source emitting gamma rays, the density of

the formation, and the distance between the source and the tool detector.

4.6 Main difference between neutron method and gamma ray method :

The natural gamma-ray tool has no source and detects the natural gamma rays that are present in therock formation outside the borehole.

A datasheet of a gamma probe is given at appendix A.



5. NEUTRON LOGGING

5.1 Definition

Neutron tools were the first logging instruments to use radioactive sources for determining the porosity of the formation.

Neutron tool response is dominated by the concentration of hydrogen atoms in the formation. In

clean reservoirs containing little or no shale, the neutron log response will provide a good measure of

formation porosity if liquid-filled pore spaces contain hydrogen, as is the case when pores are filled

with oil or water (hydrogen index =1). By contrast, when logging shale or gas-bearing formations, a

combination of Neutron and Density readings will often be required for accurate porosity

assessment.

5.2 Basic principles

The electrically neutral neutron has a mass that is practically identical to that of the hydrogen atom. The

neutrons that are emitted from a neutron source have a

high energy of several million electron volts (MeV).

After emission, they collide with the nuclei within the

borehole fluid and formation materials. With each

collision, the neutrons loose some of their energy. The

largest loss of energy occurs when the neutrons collide

with hydrogen atoms. The rate at which the neutrons

slow-down depends largely on the amount of hydrogen

in the formation.

With each collision the neutrons slow down, until the

neutrons reach a lower (epithermal) energy state and

then continue to lose energy until they reach an even lower (thermal) energy state of

fig . (5.1) General neutron logging tool

About 0.025 eV. At this energy the neutrons are in thermal equilibrium with other nuclei in the

formation. At thermal speeds, the neutrons will eventually be captured by a nucleus. When nucleus

captures a thermal neutron, a gamma ray (called a gamma ray of capture)is emitted to dissipate

excess energy within the atom.

The amount of energy lost at each collision depends on the relative mass of the target nucleus, and

the scattering cross section. (At the nuclear level, the term cross section is defined as the effective

area within which a neutron must pass in order to interact with an atomic nucleus. Such interactions

are typically classified either as neutron capture or as neutron scatter. The cross-section is a

probabilistic value dependent on the nature and energy of the particle, as well as the nature of the

capturing or scattering nucleus.



Depending on the type of tool being

used, either the gamma rays emitted

after neutron capture, the epithermal

neutrons or the thermal neutrons will

be counted.

Fig.(5.2) Emission, traveling & collisions of neutrons in

formation

The principles of neutron logging are summarized below:

· A neutron source emits a continuous flux of high-energy neutrons.

· Collisions with formation nuclei reduce the neutron energy -thereby slowing it down.

· At thermal energy levels (approximately 0.025 eV), neutrons are captured.

· Neutron capture results in an emission of gamma rays.

· Depending on the type of tool, the detector measures the slowed down neutrons and/or

emitted gamma rays.

Neutron logging devices contain one or more detectors and a neutron source that continuously emits

energetic (fast) neutrons.

Fig.(5.3) Slowing down power of H, O, SI for different neutron energies



Fig.(5.4) Neutron energy level versus time after leaving the source illustrates the slow downprocess

Porosity (or the hydrogen index) can be determined by measuring epithermal or thermal neutron

populations, or by measuring capture gamma rays, or any combination thereof.

Neutron logs that detect epithermal neutrons are referred to as sidewall neutron logs. By contrast,

the compensated neutron log, in widespread use today, detects thermal neutrons, using two

neutron detectors to reduce borehole effects. Single thermal neutron detector tools, of poorer

quality, are also available in many areas of the world.

Capture gamma rays are used for porosity determination, and logs of this type are referred to as

neutron-gamma logs. The responses of these devices are dependent upon such variables as

porosity, lithology , hole size, fluid type, and temperature.

Compensated and sidewall logs use corrections from their electronic panels to account for some of

these variables, while neutron-gamma logs require departure curves (provided in chart books) to

make corrections.



Example :

given that the lithology is dolomite with apparent porosity 15% ,which read directly from a sidewall

neutron porosity log (SNP) ,first find the apparent porosity along the scale at the bottom of the

correction chart ,then follow the line vertically until it intersect the curve representing dolomite,

finally read the true porosity on the left hand scale ,12% .

5.3 Combination Neutron Density Log

The Combination Neutron-Density Log is a combination porosity log. Besides its use a porosity

device, it is also used to determine lithology and to detect gas-bearing zones. The Neutron-Density

Log consists of neutron and density curves recorded in tracks #2 and #3 and a caliper and gamma ray

log in track #1. Both the neutron and density curves are normally recorded in limestone porosity

units with each division equal to either two percent or three percent porosity; however, sandstone and

dolomite porosity units can also be recorded.

Where an increase in density porosity occurs along with a decrease in neutron porosity in a gas-

bearing zone, it is called gas effect. Gas effect is created by gas in the pores. Gas in the pores causes

the density log to record too high a porosity (i.e. gas in lighter than oil or water), and causes the



neutron log to record too low a porosity (i.e. gas has a lower concentration of hydrogen atoms than

oil or water). The effect of gas on the Neutron-Density Log is a very important log response because

it helps a geologist to detect gas-bearing zones.

5.4 Gamma Ray-Sonic-Density–Neutron combinations

The gamma ray log measures the natural radiation of a formation, and primarily functions as a

lithology log. It helps differentiate shales (high radioactivity) form sands, carbonates, and anhydrites

(low radioactivity). The neutron log is a porosity device that is used to measure the amount of

hydrogen in a formation. The density log is a porosity device that measures electron density. When

these three logs are used together (i.e. Combination Gamma Ray Neutron-Density log), lithologies

can be determined.

5.5 NEUTRON LOGGING APPLICATIONS

Neutron tools are used primarily to determine:

· Porosity, usually in combination with the density tool

· Gas detection, usually in combination with the density tool, but also with a sonic tool



· Shale volume determination, in combination with the density tool

· Lithology indication, again in combination with the density log and/or sonic log

· Formation fluid type.

Depending on the device, these applications may be made in either open or cased holes.Additionally, because neutrons are able to penetrate steel casing and cement, these logs can be used

for depth tie-in as well as providing information on porosity and hydrocarbon saturations in cased

holes

An example of such a tool is API string tool from schlumberger (down, right) ,you can find more in

appendix B.



6. RESISTIVITY LOGS

6.1 Introduction

Electrical resistivity is a fundamental geophysical method used in both SURFACE and

SUBSURFACE geophysics. The method is legendary among Geophysical methods for exploration,

development and definition of existing targets .

Electrical resistivity is popular because it is a simple, low cost and efficient method. It is without

doubt the most practical, cost-effective logging method available today.

Most rock materials are essentially insulators, while their enclosed fluids are conductors.

Hydrocarbon fluids are an exception, because they are almost infinitely resistive. When a formation

is porous and contains salty water, the overall resistivity will be low. When the formation contains

hydrocarbon, or contains very low porosity, its resistivity will be high. High resistivity values may

indicate a hydrocarbon bearing formation.

A log of the resistivity of the formation, expressed in ohm-m. The resistivity can take a wide range of

values, and, therefore, for convenience is usually presented on a logarithmic scale from, for example,

0.2 to 2000 ohm-m. The resistivity log is fundamental in formation evaluation because hydrocarbons

do not conduct electricity while all formation waters do. Therefore a large difference exists between

the resistivity of rocks filled with hydrocarbons and those filled with formation water . Clay minerals

and a few other minerals, such as pyrite, also conduct electricity, and reduce the difference. Some

measurement devices, such as induction and propagation resistivity logs, may respond more directly

to conductivity, but are presented in resistivity.

6.2 Definition

By definition, resistivity is a function of the dimensions of the material being measured; therefore, itis an intrinsic property of that material. Resistivity is defined by the formula:

Where Electrical resistivity ρ is defined by:

Where Fig(6.1)

ρ is the static resistivity (measured in volt-metres per ampere, Vm/A);

E is the magnitude of the electric field (measured in volts per metre, V/m);

J is the magnitude of the current density (measured in amperes per square metre, A/m²).

http://www.wellog.com/ves.htm

http://www.wellog.com/elog_tool/elog_tool.htm

http://en.wikipedia.org/wiki/Insulators

http://en.wikipedia.org/wiki/Electrical_conduction

http://www.glossary.oilfield.slb.com/Display.cfm?Term=resistivity


http://www.glossary.oilfield.slb.com/Display.cfm?Term=formation%20water

http://www.glossary.oilfield.slb.com/Display.cfm?Term=clay

http://www.glossary.oilfield.slb.com/Display.cfm?Term=induction

http://www.glossary.oilfield.slb.com/Display.cfm?Term=propagation%20resistivity

http://www.glossary.oilfield.slb.com/Display.cfm?Term=conductivity

http://en.wikipedia.org/wiki/Volt

http://en.wikipedia.org/wiki/Ampere

http://en.wikipedia.org/wiki/Magnitude_(mathematics)

http://en.wikipedia.org/wiki/Electric_field


http://en.wikipedia.org/wiki/Metre

http://en.wikipedia.org/wiki/Current_density


http://en.wikipedia.org/wiki/Square_metre

http://en.wikipedia.org/wiki/Square_metre


http://en.wikipedia.org/wiki/Current_density



http://en.wikipedia.org/wiki/Electric_field

http://en.wikipedia.org/wiki/Magnitude_(mathematics)



http://www.glossary.oilfield.slb.com/Display.cfm?Term=conductivity

http://www.glossary.oilfield.slb.com/Display.cfm?Term=propagation%20resistivity

http://www.glossary.oilfield.slb.com/Display.cfm?Term=induction

http://www.glossary.oilfield.slb.com/Display.cfm?Term=clay

http://www.glossary.oilfield.slb.com/Display.cfm?Term=formation%20water


http://www.glossary.oilfield.slb.com/Display.cfm?Term=resistivity

http://en.wikipedia.org/wiki/Electrical_conduction

http://en.wikipedia.org/wiki/Insulators

http://www.wellog.com/elog_tool/elog_tool.htm

http://www.wellog.com/ves.htm



The electrical resistivity ρ (rho) can also be given by,

where

ρ is the static resistivity (measured in ohm-metres, Ωm);

R is the electrical resistance of a uniform specimen of the material (measured in ohms, Ω);

is the length of the piece of material (measured in metres, m);

A is the cross-sectional area of the specimen (measured in square metres, m²).

Finally, electrical resistivity is also defined as the inverse of the conductivity σ (sigma), of thematerial, or:

6.3 Method of operation

Resistivity logs measure some aspect of the specific resistance of the geologic formation. There are

about 17 types of resistivity logs, but they all have the same purpose which is to measure the electric

conductivity fluid in the rock. Electrical resistivity (also known as specific electrical resistance or

volume resistivity) is a measure of how strongly a material opposes the flow of electric current. A

low resistivity indicates a material that readily allows the movement of electrical charge.

In these logs, resistivity is measured using 4 electrical probes to eliminate the resistance of thecontact leads with 2 current electrodes and 2 measurement electrodes. The log must run in holes

containing electrically conductive mud or water .

6.4 Basic Principle:

The principles of measuring resistivity are illustrated in fig (6.2). If 1 amp of current from a 10-V

battery is passed through a 1-m3 block of material, and the drop in potential is 10 V, the resistivity of

that material is 10 Wm. The current is passed between electrodes A and B, and the voltage drop is

measured between potential electrodes M and N, which, in the example, are located 0.1 m apart-, so

that 1 V is measured rather than 10 V. The current is maintained constant, so that the higher theresistivity between M and N, the greater the voltage drop will be. A commutated DC current is used

to avoid polarization of the electrodes that would be caused by the use of direct current.

http://en.wikipedia.org/wiki/Rho_(letter)

http://en.wikipedia.org/wiki/Electrical_resistance

http://en.wikipedia.org/wiki/Ohm


http://en.wikipedia.org/wiki/Electrical_conductivity

http://en.wikipedia.org/wiki/Sigma_(letter)

http://en.wikipedia.org/wiki/Resistivity

http://en.wikipedia.org/wiki/Electric_current

http://en.wikipedia.org/wiki/Electrical_charge

http://en.wikipedia.org/wiki/Resistivity#Four_point_resistivity_measurement

http://en.wikipedia.org/wiki/Resistivity#Four_point_resistivity_measurement

http://en.wikipedia.org/wiki/Electrical_charge

http://en.wikipedia.org/wiki/Electric_current

http://en.wikipedia.org/wiki/Resistivity

http://en.wikipedia.org/wiki/Sigma_(letter)

http://en.wikipedia.org/wiki/Electrical_conductivity


http://en.wikipedia.org/wiki/Ohm

http://en.wikipedia.org/wiki/Electrical_resistance

http://en.wikipedia.org/wiki/Rho_(letter)



Fig (6.2). Principles of measuring resistivity in Ohm-meter. Example is 10 Ohm-meter.

There are 3 different configurations of resistivity log:

short-normal: has the smallest distance between 2 adjacent electrodes (40 cm (16 in or less)). It is

the most sensitive to thin layers but is also influenced by the drilling mud, short normal devices are

considered to investigate only the invaded zone

long-normal: long normal (162 cm (64 in)) devices are considered to investigate both the invaded

zone and the zone where native formation water is found

lateral: Lateral log has the longest distance between two adjacent electrodes (18 feet 8 inches). It

samples resistivity over a large section of sediment/rock away from the borehole. Lateral log may

miss thin beds.

6.5 Types of resistivity logs:

There are many different types of resisitivity logs, which differ primarily in how far into the rocks

they measure the resistivity. Because drilling fluids tend to force their way into the surrounding rock,

resistivity logs with shallow depths of investigation are unable to see beyond an "invasion zone" to

determine the true formation water resistivity of permeable rocks. Instead, these logs measure thelower resistivity of the contaminated zone. Thus, by pairing logs with deep and shallow depths of

investigation, it is possible to measure permeability by looking at the resistivity diffences between

the logs. The acronyms of some of the more popular resistivity logs are listed below:

AIT (Array Induction Tool) - the resistivity log of the future. It measures five depths

of investigation.

DIL (Dual Indiction Log) - a frequently used log with deep and medium depths of

investigation.

DLL (Dual Laterolog) - a frequently used log with deep and medium depths of

investigation.

LAT (Lateral Log)- an obsolete log with a deep depth of investigation.

LN (Long Normal) - an obsolete log with a deep depth of investigation.

SFL (Spherically Focused Log) - a frequently used log with a shallow depth of

investigation.

SGR (Shallow Guard Log) - a frequently used log with a shallow depth ofinvestigation.

SN (Short Normal) - an obsolete log with a shallow depth of investigation.



6.6 Calibration

resistivity logging systems may be calibrated at the surface by placing fixed resistors between theelectrodes. The formula used to calculate the resistor values to be substituted in the calibration

network shown in fig(6.3) .

Figure( 6.3). System for calibrating resistivity equipment



Wireline Logging

Sukina Y. Bader

Lara Qasem

Amal Ryahe

Sara Naser

Hanan Ahyad



2601 McHale Court

Suite 145

Austin, Texas 78758

Tel: 512-491-7541

Fax: 512-491-7561

www.cbgcorp.com

Gamma-Ray Tools

L o g g i n g t o o l s f o r o i l e x p l o r a t i o n

For Geosteering, MWD and Wireline Logging

P a g e 1 o f 4



2601 McHale Court

Suite 145

Austin, Texas 78758

Tel: 512-491-7541

Fax: 512-491-7561

www.cbgcorp.com

G a m m a T o o l D e s c r i p t i o n

The Gamma ray tool produces a measurement of the naturally occurring

radiation found in rock formations. The Gamma Log produced by these

tools is commonly used for depth correction, correlation with open hole

logs and identifying low radiation and high radiation lithologies. CBGGamma ray tools use a super sensitive hermetically sealed Sodium Iodide

Scintillator crystal and a ruggedized high temperature photomultiplier for

maximum log quality. Mechanical design techniques have been developed

specifically for the MWD/Steering tool environment to ensure a rugged and

N G T - T G a m m a T o o l

for Geosteering and MWD

The NGT-T Gamma tool has become the industry standard for Geosteering

and MWD applications. This tool was initially developed for the Steering tool

industry in 1994 and was later upgraded to meet the severe environmental

challenges of Measurement While Drilling. The standard model is equippedwith an MDM15pin male connector on the top electronics end of the tool

and an MDM15pin female connector on the bottom. This tool utilizes Pin#1

for Ground, Pin# 4 for Power and Pin# 8 for Signal. All 15 wires are passed

along a protected wire guide from top connector to bottom. Electronics

are encapsulated for additional protection. The crystal and photomultiplier

are packaged in house utilizing our proprietary, unique design for ease of

replacement or repair.

N G T - T G a m m a T o o l

with Pressure Housing Assembly

The NGT-T Gamma Tool can now be ordered to include the complete

“Tensor Compatible” mechanical assembly. The NGT-T is mounted to theBottom Bulkhead Retainer through a standard Shock Snubber Assembly. A

connector “pigtail” converts the MDM15pin connector on the tool to a 200°C,

GE, 4Pin/6Socket connector mounted within the bottom Intermodule End.

At the top, a “pigtail” converts the MDM15pin connector on the NGT-T to

a 200°C, GE, 6Pin/4Socket connector mounted within the top Intermodule

End. A custom 24” BeCu Pressure Barrel results in a significantly shorter

and lower cost tool than was previously available to the market.

N G T - C S T o o l

for Geosteering and MWD

The NGT-CS Gamma tool is the small diameter version of the popular

NGT-T. At just 1.05” OD, it offers the same performance and durability

of the NGT-T. A smaller diameter scintillator crystal with increased length

matches the sensitivity of the larger tool.

reliable tool. The short single piece aluminum chassis not only provides

maximum strength and rigidity but minimizes vibration loads due to the

low mass. The electronics are fully temperature compensated to maintain

consistent count rates through the 350°F temperature rating. The tool usesa gross counting discriminator with an energy threshold set at approximately

15KeV, significantly lower than other tools, resulting in higher count rates

and greater accuracy. CBG provides customized models of Gamma ray

tools for Geosteering and MWD.

Gamma-Ray ToolsFor Geosteering, MWD and Wireline Logging

P a g e 2 o f 4



2601 McHale Court

Suite 145

Austin, Texas 78758

Tel: 512-491-7541

Fax: 512-491-7561

www.cbgcorp.com

Shock and Vibration TestingShock and Vibration testing is routinely employed to insure that environmental

specifications are being met as well as for troubleshooting some repairs. CBG

uses the Vibration Test Systems equipment, in house to perform these tests.

Tests are performed to meet tool specifications of 50-300 Hz and 30G.

Service and Repair All tools are 100% assembled and tested by CBG. Each component of the tool

can be readily repaired or replaced. CBG has developed a reputation for fast turn

around times when service is required. The proprietary detector assembly allows

access to the scintillator crystal and photomultiplier tube for troubleshooting and

replacement, without having to send the entire assembly away to a third party for

repair. Components, assembly and test procedures are continually updated by

CBG to insure the most accurate and reliable tool on the market today!

Custom DesignsCBG will work with your Engineers to develop a customized gamma tool

design for your specific application. We have developed numerous designs for

companies that require electrical and/or mechanical changes from our standard

products.

CalibrationCBG Gamma tools are calibrated in the laboratory using an AEA Technology KUTh

Field Verifier, Product Code No. 188074, to determine the API calibration factor

for each tool. The nuclides described below are carefully chosen and combined to

closely approximate the proper ratios as found in the KUTh API Calibration Test

Pits located at the University of Houston, Houston Texas.

Nuclides Content ActivityNatural Thorium (Th-232) 90ppm 0.168 uCi

Natural Uranium (U-238) 40ppm 0.233 uCi

Natural Potassium (K-40) 11.7% 1.685 uCi

Temperature StabilityCBG Gamma Tools are fully rated to 350°F, with a survival rating up to 400°F.

Electronic circuits are temperature compensated to maintain consistent count rates.

Each tool, new and repaired, is logged in the laboratory from room temperature to

350° and back to insure a count rate stability of no less than 95%.

D G A F o c u s e d G a m m a T o o l

The DGA Focused, or Azimuthal Gamma tool is a Tungsten collimated

version of the NGT-T tool. It is mechanically and electrically identical to

the NGT-T. A “window” is machined along the length of the Tungsten shieldthat surrounds the detector. Only gamma rays entering from the formation,

through this window can be detected and counted. When aligned with the

tool face or other physical reference, the DGA indicates the direction from

which gamma ray intensities originate.

N G T - B G a m m a T o o l

for Wireline

The NGT-B Gamma Tool is a fully housed 1 11/16” OD, wireline logging tool. It is

available to operate with the CBG high speed digital telemetry or as an analog, pulse

output tool. The NGT-B incorporates the standard GO single-pin interface. Titanium

housings and subs not only provides maximum protection in sour-gas environments, but

minimizes attenuation of gamma rays due to the low density. Temperature compensated

electronics insure stable count rates over the full temperature range to 350°F.

N G T - S G a m m a T o o l

for Wireline

The NGT-S Gamma Tool is the small diameter version of the NGT-B, with an OD of

1.375”. Tool performance and stability are not sacrificed for this slim hole version of

the NGT-B.

CBG AzimuthalGamma-RayResponse

Using a NaturalUranium Source,

Angle relative to

Window

Surface of tool

4 inches of radius

Typical Temperature Stability of Count RateNGT-T MWD Gamma-ray Tool

P a g e 3 o f 4



NGT-Tw/out housing assembly

NGT-Twith housing assembly

NGT-CS DGAFOCUSED GAMMA

NGT-B NGT-S

Application Geosteering/MWD Geosteering/MWD Geosteering/MWD Geosteering/MWD Wireline/Production Wireline/Production

Mechanical

Diameter (OD) 1.36” 1.875” 1.050” 1.30” 1.6875” 1.375”

Length (make up) 13.6” 34.05” 18.83” 13.6” 22.25” 25.2”

Weight 1.7 lb. 15.0 lb. 1.5 lb. 3.0 lb. 6.0 lb. 4.0 lb.

Operating Temp. -77° to +350° F. -77° to +350° F. -77° to +350° F -77° to +350° F -77° to +350° F -77° to +350° F

End Connectors MDM-15 Pin 200°C, 10 Pin GE MDM-15 Pin MDM-15 Pin GO Single Pin GO Single Pin

Material BeCu Ti-6Al-4V Ti-6Al-4V

Pressure 18,000 PSI 18,000 PSI 18,000 PSI

Performance

Sensitivity 2.0 Counts per API 1.7 Counts per API 1.8 Counts per API 0.6 Counts per API 1.7 Counts per API 1.5 Counts per API

Accuracy+/- 5% to 300° F.

+/- 10% to 350° F.

+/- 5% to 300° F.

+/- 10% to 350° F.

+/- 5% to 300° F.

+/- 10% to 350° F.

+/- 5% to 300° F.

+/- 10% to 350° F.

+/- 5% to 300° F.

+/- 10% to 350° F

+/- 5% to 300° F.

+/- 10% to 350° F

Resolution (Thin-Bed, 8” hole diameter, 50% points)

6.8” 6.8” 6.8” 8.8” 8.8” 8.8”

Environmental

Survival Temp. 400° F. 400° F. 400° F. 400° F. 400° F. 400° F.

Max Heat/Cool 5° F./Minute 5° F./Minute 5° F./Minute 5° F./Minute 5° F./Minute 5° F./Minute

Vibration (3 axis) 50-300 Hz

Random

30 G.

30 G.

30 G.

30 G.

30 G.

30 G.

30 G.

30 G.

30 G.

30 G.

30 G.

30 G.

Shock (Z-axis) 500 G., 0.5 mS. 500 G., 0.5 mS. 500 G., 0.5 mS. 500 G., 0.5 mS. 250 G., 0.5 mS. 250 G., 0.5 mS.

Shock (Y-axis) 1000 G., 0.5mS. 1000 G., 0.5mS. 1000 G., 0.5mS. 1000 G., 0.5mS. 500 G., 0.5mS. 500 G., 0.5mS.

Power Requirements

Input Voltage 22-30 Volts 22-30 Volts 22-30 Volts 22-30 Volts 46-48 Volts 46-48 Volts

Input Current18-14 mA.(constant power)

18-14 mA.(constant power)



20-23 mA 20-23 mA

Maximum Voltage 31.5 Volts 31.5 Volts 31.5 Volts 31.5 Volts 50 Volts 50 Volts

Output Signal

Pulse+5V to 0V, 2(+/-0.5)microseconds

+5V to 0V, 2(+/-0.5)microseconds



CBG Telemetry /Pulse CBG Telemetry / Pulse

C B G G a m m a - R a y T o o l S p e c i f i c a t i o n s

Gamma-Ray ToolsFor Geosteering, MWD and Wireline Logging

P a g e 4 o f 4

For more information, call us today at 512-491-7541

Wireline Logging Full Report

Documents

Transcript of Wireline Logging Full Report