“Formation Evaluation with the help of Wire-line Logging tools, Advanced Logging tools and

Subsurface Borehole Image Interpretation”

DISSERTATION SUBMITTED

IN PARTIAL FULFILMENT OF THE REQUIREMENTS

FOR THE AWARD OF THE DEGREE OF

5 YEAR INTEGRATED MASTER OF SCIENCE & TECHNOLOGY

BY

ALOK SHUKLA ADMISSION NO. 2010JE0419

DEPARTMENT OF APPLIED GEOLOGY INDIAN SCHOOL OF MINES, DHANBAD

ACKNOWLEDGEMENT

At the very outset I express my deepest gratitude to my guide Prof. A.S. Venkatesh, Department of Applied Geology, Indian school of Mines, Dhanbad for his valuable guidance, moral support and encouragement from time to time during this dissertation work.

I extended my thanks to Director, Indian School of Mines, Dhanbad for providing facilities to carry out this work.

I am thankful to Prof. A. K. Varma, Head, Department of Applied Geology, Indian School of Mines for providing the necessary facilities to complete this work. I express my profound sense of respect to Dr. Sahendra Singh and Dr. Prabodh Ranjan Sahoo, Assistant professors, Department of Applied Geology, Indian School of Mines, Dhanbad who helped me to take this opportunity to pursue my work. I am very much thankful to all the teachers of my department for their encouragement and support.

My grateful thanks to Mr. A.K.S.Kakani Sir (Head, Formation Evaluation Center, HLS Asia Ltd), Mr. Ajay Kumar Sir (Vice President, HLS Asia Ltd), Mr. Durgesh Jharbade Sir (Director, HLS Asia Ltd), Mr Vijay Khera Sir (Vice President, HLS Asia Ltd) for giving direction during the project work. I also express my sincere gratitude to Mr. Rajeev Grover Sir ( Managing Director, HLS Asia Ltd) to provide me opportunity of Summer Internship from (1st May 2014 to 26th July 2014).

I completed my project work on the basis of data given by HLS Asia Ltd during my Summer Internship (1st May 2014 to 26th July 2014) and I express my thanks to Mr. R.N. Chakraborty Sir, Mr. Ajit Saxena Sir, Mr. Ravinder Kumar Bharadwaj Sir, Mr. Arka Basu Sir for providing me valuable guidance during my summer internship project work. I am also thankful to complete authorities of HLS Asia Ltd for continuous support during the Internship.

I want to give special thanks to my seniors, Ms Vandana Jha, Mr. Rahul Mukherjee, Mr. Shriram Suman Sahoo, Ms Puja Kumari, Research Scholars, Applied Geology, Indian School of Mines, Dhanbad for their help in completing this work.

I express deepest feeling of relevance and love to my parents, their moral support, encouragement, benediction and care inspired me to complete this field work. Last but not the least, I am also thankful to all of my classmates for their suggestions and generous help during the course of investigations and till the preparation of this report.

This work does not contain any confidential information gathered from any institute/organization and original work is carried out by me.

Date: 01.05.2015 Alok Shukla

Place: Dhanbad Adm. No. 2010JE0419

CERTIFICATE

This is to certify that Mr. Alok Shukla has worked under my guidance on the topic

“Formation Evaluation with the help of Wire-line Logging tools, Advanced Logging tools

and Subsurface Borehole Image Interpretation” in partial fulfillment of the requirement

for the award of 5 Year Integrated Master of Science Technology degree in Applied

Geology of Indian School of Mines Dhanbad

This is further stated that this work has not been presented for any other degree or

diploma or other similar distinction elsewhere.

Forwarded By:

Prof A.K.Verma

Head of Department

Department of Applied Geology

Indian School of Mines

Jharkhand-826004

Guided By:

Prof. A.S. Venkatesh

Professor

Department of Applied Geology

Indian School of Mines

Jharkhand-826004

Abstract

The Formation Evaluation with the help of wire-line logging tools, Advanced Logging Tools and Subsurface Borehole Image Interpretation was done. For the formation evaluation we did the Basic and Advanced Wire-line Logging Tools Study of a well by Identification of Reservoir, Non Reservoir Zone, Analysis of Logging Data of the field (Gamma, Caliper, Density, Neutron, and Resistivity) Borehole correction application with help of Halliburton chart, Calculation of water saturation, hydrocarbon estimation, reserve estimation Graph of comparison of various quantities and Analysis of XRMI Logs of the wells and finding Thin beds and Geology of the area. Identification of Reservoir, Non Reservoir Zone. We did analysis of Logging Data of the field (Gamma, Caliper, Density, Neutron, Resistivity) and the borehole correction application with help of Halliburton chart. Then the Calculation of water saturation, hydrocarbon estimation, reserve estimation was done. Analysis of XRMI Logs of the wells and finding thin beds and Geology of the area and the analysis of Wave Sonic Log of the field was also done.

Table of Contents

Chapter I.......................................................................................................................................... 7

Introduction ................................................................................................................................. 7

Density Logging Tool............................................................................................................. 7

Neutron Logging Tool ........................................................................................................... 7

Gamma Ray Logging............................................................................................................. 7

Resistivity Logging ................................................................................................................ 7

Sonic Logging ......................................................................................................................... 7

XRMI ...................................................................................................................................... 8

WSTT ...................................................................................................................................... 8

NMR ........................................................................................................................................ 8

Objectives ................................................................................................................................ 8

Chapter II ........................................................................................................................................ 9

Logging Tools ............................................................................................................................. 9

II.1 Gamma Ray Logs .............................................................................................................. 9

II.2 Sonic Log ........................................................................................................................ 13

II.3 Density Log (Gamma-Gamma Ray Log) ........................................................................ 15

II.4 Neutron log ..................................................................................................................... 18

II.5 Resistivity Log ................................................................................................................ 20

Chapter III ..................................................................................................................................... 21

X- tended Range Micro Imager (XRMI) Tool ............................................................................ 21

XRMI Tool Specifications ..................................................................................................... 23

Operating Principle ................................................................................................................ 24

XRMI : Measurement Principle ............................................................................................ 26

XRMI: Operating Principle ................................................................................................... 27

Depth of Investigation ........................................................................................................... 28

Chapter IV ..................................................................................................................................... 30

Wave Sonic Tool ....................................................................................................................... 30

Wave Sonic features .................................................................................................................. 30

•Applications ............................................................................................................................. 31

Chapter V ...................................................................................................................................... 32

Reservoir monitoring tool (RMT) ............................................................................................. 32

Formation evaluation of well 1 ................................................................................................. 33

Chapter VI ..................................................................................................................................... 35

Methodology ............................................................................................................................. 35

Data Analysis ............................................................................................................................ 36

Wave Sonic Report of the well ................................................................................................. 44

Chapter VII ................................................................................................................................... 45

Results and Discussion .............................................................................................................. 45

Formation Evaluation Report of Unconventional Well 1 ...................................................... 45

Table of Figures ............................................................................................................................ 47

References……………………………………………………………………………………………

………………………47

List of Figures

Figure 1: Gamma Ray Logging .................................................................................................... 10 Figure 2: Gamma Ray Interactions ............................................................................................... 11 Figure 3: Typical Gamma Ray responses ..................................................................................... 12 Figure 4: Source and Receiver in Sonic Logging ......................................................................... 13 Figure 5: Sonic Log Raypaths and recorded waveforms .............................................................. 14 Figure 6: Density Logging tool ..................................................................................................... 15 Figure 7: Working of Density Logging tool ................................................................................. 16 Figure 8: Neutron Logging tool .................................................................................................... 18 Figure 9: XRMI Raw Data ............................................................................................................ 21 Figure 10: EMI vs XRMI .............................................................................................................. 23 Figure 11: XRMI Tool .................................................................................................................. 24 Figure 12: Operation of XRMI ..................................................................................................... 25 Figure 13: Measurement using XRMI .......................................................................................... 26 Figure 14: Operating Principle of XRMI ...................................................................................... 27

Figure 15: Log responses ............................................................................................................................ 44

Chapter I

Introduction

We did the Formation Evaluation with the help of wire-line logging tools, Advanced Logging Tools and Subsurface Borehole Image Interpretation. For the formation evaluation we did the Basic and Advanced Wire-line Logging Tools Study of five Wells of various Field by Identification of Reservoir, Non Reservoir Zone, Analysis of Logging Data of the field (Gamma, Caliper, Density, Neutron, and Resistivity)Borehole correction application with help of Halliburton chart, Calculation of water saturation, hydrocarbon estimation, reserve estimation Graph of comparison of various quantities and Analysis of XRMI Logs of the wells and finding Thin beds and Geology of the area.

Definitions

Density Logging Tool A density-logging tool sends gamma rays into a formation and detects those that are scattered back. Typical logging sondes use a Cesium-137 source, which emits gamma rays of 0.66Me.

Neutron Logging Tool The log targets the average hydrogen density of the volume investigation.

Gamma Ray Logging Natural occurring radioactive materials (NORM) include the elements uranium, thorium, potassium, radium, and radon, along with the minerals that contain them. Logging tools have been developed to read the gamma rays emitted by these elements and interpret lithology from the information collected.

Resistivity Logging Resistivity logging is a method of well logging that works by characterizing the rock or sediment in a borehole by measuring its electrical resistivity.

Sonic Logging Sonic logging is a well logging tool that provides a formation’s interval transit time, designated as , which is a measure of a formation’s capacity to transmit seismic waves.

XRMI XRMI is basically a contrast resistivity image of the wall-bore it essentially gives the fracture image the dip of the formation and high / low resistivity formation delineation.

WSTT The Wave Sonic crossed-dipole sonic tool properly defines sonic attributes that can improve 3-D seismic analysis. The Wave Sonic tool measures fast and slow shear wave travel times, P-wave slowness, compressive fluids in pore space, and anisotropy orientation. The tool even calculates minimum and maximum principal stresses and stress field orientation.

NMR NMR logging, a subcategory of electromagnetic logging, measures the induced magnet moment of hydrogen nuclei (protons) contained within the fluid-filled pore space of porous media (reservoir rocks).

Objectives

1. Identification of Reservoir, Non Reservoir Zone 2. Analysis of Logging Data of the field (Gamma, Caliper, Density, Neutron, Resistivity) 3. Borehole correction application with help of Halliburton chart. 4. Calculation of water saturation, hydrocarbon estimation, reserve estimation 5. Graph of comparison of various quantities. 6. Analysis of XRMI Logs of the wells and finding thin beds and Geology of the area. 7. Analysis of Wave Sonic Log of the field.

Chapter II

Logging Tools

II.1 Gamma Ray Logs Gamma ray logs are lithology identification tools are used for six main purposes:

Correlation between wells,

Determination of bed boundaries,

Evaluation of shale content within a formation,

Mineral analysis,

Depth control for log tie-ins, side-wall coring, or perforating, and

Tracking movement of radioactive tracers

Gamma ray (GR) logs measure the natural gamma ray emissions from subsurface formations. Because gamma rays can pass through steel casing, measurements can be made in both open and cased holes.

Gamma ray tools consist of a detector and the associated electronics for passing the gamma ray count rate to the surface. These tools are in the form of double-ended subs that can be sandwiched into practically any logging tool string; thus, the GR log can be run with practically any tool available.

Gamma rays originate from three main sources in nature: the radioactive elements in the uranium and thorium groups, and potassium. Uranium 235, uranium 238, and thorium 232 all decay, via a long chain of daughter products, to stable lead isotopes. An isotope of potassium, K40, decays to argon.

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Figure 1: Gamma Ray Logging

The Gamma Ray log is a measurement of the formation's natural radioactivity.

Gamma ray emission is produced by three radioactive series found in the Earth's crust.

Potassium (K40) series.

Uranium series.

Thorium series.

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Gamma rays passing through rocks are slowed and absorbed at a rate which depends on the formation density.

Less dense formations exhibit more radioactivity than dense formations even though there may be the same quantities of radioactive material per unit volume.

Gamma Ray Interactions

As they pass through matter, gamma rays experience a loss of energy due to collisions with other atomic particles. These collisions can be divided into three basic categories :

• Pair production: converts GR into electron & proton

• Compton Scattering: GR collides with formation and loses its energy

• Photoelectric Absorption: GR absorbed by an atom in the formation

Figure 2: Gamma Ray Interactions

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Bed definition:

The tool reacts if the shale is radioactive (usually the case), hence show the sands and shales, the permeable zones and non-permeable zones

Computation of the amount of shale:

The minimum value gives the clean (100%) shale free zone, the maximum 100% shale zone. All other points can then be calibrated in the amount of shale

Vsh=(GRlog- GRsand)/(GRshale-GRsand)

Figure 3: Typical Gamma Ray responses

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II.2 Sonic Log A log that measures interval transit time (Δt) of a compressional sound wave travelling through the formation along the axis of the borehole The acoustic pulse from a transmitter is detected at two or more receivers. The time of the first detection of the transmitted pulse at each receiver is processed to produce Δt. The Δt is the transit time of the wavefront over one foot of formation and is the reciprocal of the velocity. Interval transit time is both dependent on lithology and porosity .Sonic log is usually displayed in track2 or 3 Its unit is μsec/ft, μsec/m.

Geologically, this capacity varies with lithology and rock textures, most notably decreasing with an increasing effective porosity. This means that a sonic log can be used to calculate the

porosity of a formation if the seismic velocity of the rock matrix, , and pore fluid, , are known, which is very useful for hydrocarbon exploration.

Figure 4: Source and Receiver in Sonic Logging

Interpretation goals:

–Porosity

–Lithology identification (with Densityand/or Neutron)

–Syntheticseismograms (with Density)

–Formationmechanical properties(withDensity)

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–Detectionofabnormal formationpressure

–Cementbondquality

Figure 5: Sonic Log Raypaths and recorded waveforms

Sonic Porosity Formula

•From the Sonic log, a sonic derived porosity log (SPHI) may be derived:

–Wyllie Time-average

•SPHI Units: percent, fraction

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II.3 Density Log (Gamma-Gamma Ray Log)

Gamma rays emitted from a chemical source (Ce137, Co60) interact with electrons of the elements in the formation. Two detectors count the number of returning gamma rays which are related to formation electron density. For most earth materials, electron density is related to formation density through a constant Returning gamma rays are measured at two different energy levels

–High energy gamma rays (Compton scattering) determine bulk density and therefore porosity

–Low energy gamma rays (due to photoelectric effect) are used to determine formation lithology Low energy gamma rays are related to the lithology and show little dependence on porosity and fluid type.

Figure 6: Density Logging tool

Interpretation goals

–Porosity

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–Lithology identification (from PEF and/or with Sonic and/or Neutron)

–Gas indication (with Neutron)

–Synthetic seismograms (with Sonic)

–Formation mechanical properties (with Sonic)

–Clay content (with Neutron)

Figure 7: Working of Density Logging tool

The formation density skid device carries a gamma ray source and two detectors, referred to as the short-spacing and long-spacing detectors.

This tool is a contact-type tool; i.e., the skid device must ride against the side of the borehole to measure accurately.

The tool employs a radioactive source which continuously emits gamma rays. These pass through the mudcake and enter the formation, where they progressively lose energy until they are either completely absorbed by the rock matrix or they return to one the two gamma ray detectors in the tool.

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Gamma rays can react with matter in three distinct manners-

Photoelectric effect

Compton scattering

Pair production

Density Porosity Formula

Formationbulk density(ρb) is a functionofmatrix density(ρma), porosityand formationfluid density(ρf)

•Densityporosityis defined as:

•Thematrixdensityand the fluid densityneedto be known

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II.4 Neutron log

Neutron tools emit high energy neutrons from either a chemical source or a neutron generator device and measure the response of these neutrons as they interact with the formation, or the fluids within the formation. This measured response is affected by the quantity of neutrons at different energy levels and by the decay rate of the neutron population from one given energy level to another. A neutron interacts with the formation in a variety of ways after leaving the source.

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 and water (Hydrogen index=1).

Figure 8: Neutron Logging tool

Neutron curves commonly displayed in track2 or 3

•Displayed as Neutron Porosity (NPHI, PHIN, NPOR)

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•Units: porosity units(p.u.)

Neutron tools are used primarily to determine:

porosity, usually in combination with the density tool

gas detection, usually in combination with the density 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

NPHI = (1-Φn) * NPHIma + Φn * NPHIf

Φn– Neutron Porosity

NPHI = Porosity value on the log

NPHIma = Porosity value of the matrix

NPHIf = Porosity value of the formation

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II.5 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 4 electrical probes to eliminate the resistance of the contact leads. The log must run in holes containing electrically conductive mud or water.

Resistivity logging is sometimes used in mineral exploration (especially exploration for iron and potassium) and water-well drilling, but most commonly for formation evaluation in oil- and gas-well drilling. 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.

Usually while drilling, drilling fluids invade the formation, changes in the resistivity are measured by the tool in the invaded zone. For this reason, several resistivity tools with different investigation lengths are used to measure the formation resistivity. If water based mud is used and oil is displaced, "deeper" resistivity logs (or those of the "virgin zone") will show lower conductivity than the invaded zone. If oil based mud is used and water is displaced, deeper logs will show higher conductivity than the invaded zone. This provides not only an indication of the fluids present, but also, at least qualitatively, whether the formation is permeable or not.

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Chapter III

X- tended Range Micro Imager (XRMI) Tool

Identify reservoir rock properties based on an image developed from qualitative micro- resistivity readings. Extends the range of operation in highly resistive formations and highly conductive boreholes.

Figure 9: XRMI Raw Data

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XRMI (Halliburton)provides image by measuring and mapping formation micro-resistivity with each of the pad-mounted buttons. Each button’s current is recorded as a curve, sampled at 0.1 inch or 120 samples/foot.Curves reflect the relative micro-resistivity variations within the formation.

Development History

• Four Electrode Dipmeter (FED)

• Six Electrode Dipmeter (SED)

• EMI (Electrical Micro Imaging)

• XRMI (water based mud application)

• OMRI (Oil base mud application)

EMI(Electrical Micro Imaging) Problems

Low power for high resistivity formations

Low quality image in very salty muds and high resistivity formations.

Cross-talk among pads

Errors in the communication between pads and electronics.

One failing pad could shutdown the hole tool-string

XRMI extends the range of operation by-

Features that allows the use of external DC power to operate the transmitter.

Digitization of the button data in the pad: eliminates the cross-talk.

The used of DSP (Digital signal processing) in processing button data eliminating noise and offset errors.

Use of DSP allows both R and X components of the button signal to be used in constructing the image.

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The challenge: Very low Rm(Measured Resistivity) and very high Rt(True Resistivity)

Common in exploratory areas and fractured reservoirs .In Carbonate reservoirs,Rt:Rm ratio is as high as a million.Older generation images lacked clarity in such cases.Older generation EMI image lacks clarity and XRMI image reveals geology.

Figure 10: EMI vs XRMI

XRMI Tool Specifications • Operating range of 0.2-10,000 Ohm-m (0.2 – 2,000 Ohm-m for EMI)

• XRMI can operate well in 0<Rt/Rm<20,000.

• XRMI can drive five times more power survey current into the formation for better

image definition.

6 independent arms caliper actuated to minimize the loss of pad contact that is due to hole eccentricity or tool decentralization. Axial articulation of the imaging pads further reduces pad liftoff

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Figure 11: XRMI Tool

o Vertical resolution: 0.20”

o 67% coverage of 8” BH

o Hole Size: 5 7/8” - 21” o

350 deg, 20,000 psi

o Logging Speed: 30 fpm

Operating Principle

XRMI is based on the micro laterolog principle.XRMI is a focused resistivity device.The mandrel serves as the guard electrode and creates an equipotential field parallel to the borehole wall in the vicinity of the six imaging pads. Each imaging pad contains 25

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buttons that act as the Ao electrode. Currents entering the buttons are focused through the target formation by the long guard electrode. The amplitudes of these currents are determined by the resistivity of the formation in front of each button.

Figure 12: Operation of XRMI

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XRMI : Measurement Principle

• 2kHz drive signal from transmitter is transformer coupled to mandrel body and current return. The telemetry and gamma sub housings are used as the current return electrode.

• Mandrel is isolated from the current return by an inbuilt isolator on the electronics section.

• Fiberglass sleeves at the upper part of the mandrel provide isolation.

Figure 13: Measurement using XRMI

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• Button electrodes connected to mandrel via 10 ohm resistors. Each button emits a survey current.

• Button survey current is focused by the guard current and return to the current return.

• The Voltage drop across the 10 ohm at each button is measured and used to compute the resistivity of the formation in front of the electrode.

XRMI: Operating Principle

Figure 14. Operating Principle of XRMI

Figure 14: Operating Principle of XRMI

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• Armor is used as a voltage reference electrode to measure the voltage between the lower mandrel and the armor (EMEX)

• The current flow in the center button of each pad and survey voltage (EMEX) are used to compute the calibrated resistivity of the formation as

R = PadC *E/I

Where:

E= Emex Voltage,

I = Button current

PadC= electronics cal factor button 13

R= Measured button resistivity.

Depth of Investigation

After the button currents flow into the formation for 12 inches, the area into which each current is flowing will be enlarged to a significant point. At that point, the additional formation media traversed by the current contributes only marginally to the total resistance from the button to the current return electrode that is seen by the button current.The effect of the fiberglass sleeves on the mandrel and instrument section housing serves to delineate the guard (focus) electrode length. Longer guard electrode lengths above and below the pads would increase the depth of investigation of the survey current. This increase is not desirable because the effect of dipping beds is "seen" on the image before the bed boundary is traversed at the borehole wall. Additionally, the effectiveness of statistical dipmeter correlation techniques can be degraded. Shorter guard electrodes can result in inadequate focusing, especially in salt-mud environments. On the image, pad-to- pad similarity can degrade due to the relative guard electrode differences for "up" and "down" pads, or due to differing pad extensions from the tool body. The use of a second current return, which can be located below the mandrel, will help improve focusing and minimize these effects.

Navigation Sensor

Determines the tool's orientation with respect to vertical and magnetic North. The sensor is equipped with three accelerometers and three magnetometers that are orthogonally

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mounted.The accelerometers respond to the force of the Earth's gravitational field and are used to calculate the tool's angle of deviation from vertical.The magnetometers react to the Earth's magnetic field and are used to calculate the orientation of the tool axis with respect to Pad-1 and magnetic North.

Relative Bearing

The RB is the clockwise angle looking downhole, from the high side of the tool (or borehole) to Pad 1 (the tool reference direction).The RB is calculated using accelerometers ACCX and ACCY as follows:

Relative Bearing= ArcTan(ACCX/ACCY)

Deviation

This curve is also known as Inclination and Drift Angle.The DEVI is the angle from vertical (down) to the central tool axis (or the borehole axis). The DEVI is calculated using accelerometers ACCX, ACCY, and ACCZ as follows:

Deviation=Arcsin{(ACCX2 + ACCY2)/(ACCX2 + ACCY2 +ACCZ2)}

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Wave Sonic Tool

Chapter IV

It is a Third Generation Crossed Dipole Wireline Logging Tool and is an evolutionary upgrade using new technology .It has robust mechanical design. WSST has fully surface programmable for tool operations.96 waveforms acquired and sent to surface computer per 1/2 foot depth sample .It has a logging speed of 1800 ft /hr.

The WaveSonic crossed dipole sonic tool provides simultaneous monopole, XX dipole and YY dipole sonic measurements. The dipole flexural wave propagation allows for the measurement of shear wave slowness is virtually all formation conditions. The compressional P-wave slowness, refracted shear wave slowness, and Stoneley wave properties are obtained from the monopole data. The robust mechanical design of this tool allows for drillpipe conveyed logging, and it is not limited to bottom of the tool string.

The shear wave slowness in the XX and YY directions and the monopole P-wave slowness are the basic wells site deliverables. The WaveSonic tool differentiates itself from other sonic tools by sending all 96 waveforms to the surface (32 monopole, 32 YY dipole, and 32 XX dipole). Other dipole tools on the market do downhole subtraction and only retain the A-C and B-D waveforms.With the WaveSonic tool all of the in-line and cross-line receiver data is digitized and recorded on the surface computer system. The fast and slow shear wave travel times are obtained with advanced waveform processing methods in Halliburton computing centers strategically located throughout the world. Anisotropy Analysis provides the fast and slow shear wave travel times as a simultaneous solution of 64 waveforms (32 XX and 32 YY). Also, the combination telemetry rate and fast tool electronics gives a logging speed of 30 ft/min for full cross dipole.TheWavesonic tool’s source is surface programmable, and allows

selection of the optimal frequency to excite the formation for vibration in the flexural wave resonance mode.

Wave Sonic features

The WaveSonicSM service provides simultaneous monopole and crossed dipole sonic information. P-wave and S-wave slowness can be obtained in formation conditions ranging from poorly consolidated high porosity gas saturated sandstones to low porosity carbonates. The flexural wave energy is propagated from a low frequency on-depth crossed dipole bender-bar source.

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The low frequency flexural wave travels at the true shear slowness of the formation. As a result, dispersion corrections for shear wave slowness are not required. A low frequency monopole source is utilized, so the P-wave and flexural wave data have similar depths of investigations well beyond any near wellbore alteration.

The Wave Sonic tool offers the following benefits: Low frequency monopole and dipole sources for deeper investigations of sonic slowness

measurements beyond any near-wellbore alteration effects

Broadband eight-level, quad-receiver array for high-quality waveform data; all 96 waveforms for each set of transmitter firings are recorded at the surface for advanced waveform processing techniques

On-depth, low frequency bender bar source provides a clean source signal

o No need for dispersion corrections for slowness determination

o No depth shifting of waveform data for anisotropy analysis

Robust tool isolator design allows for drillpipe conveyed operations;WaveSonic tool not limited to bottom of tool string

Applications

•Porosity calculation

•Seismic Ties

•Pore Pressure prdiction

•Permeability Indication

•Fracture Detection / Anisotropy

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Chapter V

Reservoir monitoring tool (RMT)

RMT tool distinguish hydrocarbon bearing zones from water wet layers behind casing. This is achieved by measuring elemental carbon present in oil and elemental oxygen present in water. Carbon-oxygen ratio measurement is based on C and O reactions with high energy neutrons producing characterstic gamma rays. From this measurement one can distinguish between hydrocarbon( C+H) and (H+O) layers. For RMT processing porosity must be high , it does not work for porosity less than 10%.

Aspects of RMT:

Identification and evaluation of hydrocarbon in low salinity formation water environment.

Monitoring of reservoir depletion.

Oil saturation analysis for initial well completionwhen open hole logs are not obtainable.

Identification of nature of fluid.

Diagnose production problems such as water influx and injection water breakthrough.

Designing enhanced recovery strategies.

Concept:

High energy neutrons are bombarded into the formation and the inelastic gamma and the capture gamma spectra are recorded .

Spectral data is utilized to extract C/O and Ca /Si ratio.

Bulk sigma and elemental yield which are used for interpretation.

In porous rock as hydrocarbon replaces C conc increases and O conc decreases so C/O increases.

However C/O could also increase if sands are replaced by lime.

Hence need of another curve which will tell us wheather increase in C/O is either due to hydrocarbon or due to lime.

If in a given clean reservoir the C/O increases without increase in Ca / Si then there is a very good probability that the reservoir is saturated with hydrocarbon.

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Objective of RMT:

To find out left over hydrocarbon saturation behind the casing.

Formation evaluation of well 1:

a) Mud parameter: Interval: 2642-2759m

Surface temp. 82F

Mud weight 1.32G/CC

Rm .12 @ 82F

Rmf .08 @ 82F

Rmc .14 @ 82F

BHT 260F@ 2886.2m

Bit size 2642-2755m

b) Equations used

Archies equation

Indonesian equation

c)a, m and n parameters used:

Tortuosity factor a=.62

Cementation factor m=2.15

Saturation exponent n=2

Discussion and interpretation:

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Water bearing zones have high water saturation and hydrocarbon bearing zones have low water saturation. In the (well 1) zones are classified as ;

Formation water resistivity= .088

Water bearing zone- zone1(2646-2657m), zone2(2678-2682), zone3(2690-2698m) Gas bearing zone- zone 4 at 2658m Oil bearing zone- zone 5 (2700-2724m)

Volume of shale is calculated in every zone and it is minimum in zone (26922698)

Porosity of Reservoir Zones is corrected for shaliness effect and hydrocarbon effect and water saturation in formation (Sw) and in flushed zone (Sxo) is calculated at each step.

Moveable Hydrocarbon Fraction is plotted Via (Effective porosity Vs its product with Sw and Sxo) in every Zone.

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Chapter VI

Methodology

Formation Evaluation with the help of wire-line logging tools, Advanced Logging Tools and Subsurface Borehole Image Interpretation

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Data Analysis:

37

38

39

40

Movable Oil Plot

Blue = water Green= Residual Hydrocarbon Red = Movable Hydrocarbon

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Chapter VII

Results and Discussion

Formation Evaluation Report of Unconventional Well 1: According to the given well log resistivity values are going high hence oil based

mud has been used.

There are three hydrocarbon reservoir zones in the depth range given. The sequence of

Shale Above-150

Water 150-163

Thin Shale Bed 163-175

Hydrocarbon 176-178 Oil Zone

Water 180-343

Shale 343-389

Hydrocarbon 449-460 Doubtful Zone

Water 460-503

Shale 503-515

Hydrocarbon 515-523 Oil Zone

Water Below 523

The given well is basically contains Unconventional Reservoirs, Hydrocarbon traps

are disturbed traps due to earlier activities. As shale layers are present, working as

cap rock. Hence our zones of interest are-

1. (176-178 m) GR values are low enough to have reservoir, resistivity values are near to resistivity of Oil, Neutron density curves also indicating the same.

Porosity = 30-40 %

shale = 30-45 %

Sw = 30-50 %

Rw min = .102

42

2. (449-460 m)

As Vsh is very low , which inticating it as good reservoir zone, GR values are also low

enough, but as resistivity is not sufficient to predict oil zone so it is doubtful zone.

Porosity = 40-45 % Vshale = 10-30 % Sw = 50-60 %

Rw min = .07

3. (515-523m)

As we have sufficient porosity in this zone, and resistivity values are indicating presence of

hydrocarbon, hence the reservoir zone is oil reserve.

Porosity = 36-46%

Vshale = 20-30%

Sw= 0.3-35%

Conclusion

The given well is contains Unconventional Reservoirs, Hydrocarbon traps are disturbed

traps due to earlier activities. As shale layers are working as cap rock. Hence our zone of

interest are (176-178 m), (449-460 m) and (515-523m).

43

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