Internship Report

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2017
INTERNSHIP
REPORT
EXPLORAION DEPARTMENT,
HEAD OFFICE ISLAMABAD
MPCL
WAQAS AHMED
UNIVERSITY OF AZAD JAMMU AND
KASHMIR MUZAFFARABAD
MENTOR: SIR WAQAR AHMED
Contact No #03355268624

MPCL Internship Report
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DEDICATION
Dedicated To
Our Holy Prophet ( )
Who guides us towards the path of success
My Loving Parents
Who determined the path and destination for me and who always make things
Possible for me.
My Loving Family
Whose prayers and support enabled me to complete my studies.
My Best Friends
For their company, advice and cooperation at the time of need.

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Table of Contents
1. Introduction………........................................................................................................6
2. Overview of G&G/exploration activities in MPCL .....................................................7
2.2 MPCL Operated Blocks........................................................................................7
2.3 MPCL Non-operated Blocks................................................................................8
2.4 Prospectivity Zones Maps (PPIS)........................................................................9
3. Exploration cycle.........................................................................................................10
3.1 Block Evaluation................................................................................................11
3.2 Block Carve out.................................................................................................11
3.3 Block Bidding....................................................................................................11
3.4 Block Award......................................................................................................12
3.5 Reserves.............................................................................................................13
3.6 Budget................................................................................................................14
4. Basin of Pakistan..........................................................................................................16
4.1 Indus Basin.........................................................................................................16
4.2 Upper Indus basin..............................................................................................16
4.2.1 Kohat Basin................................................................................................16
4.2.2 Potwar Basin..............................................................................................16
4.2.3 Source Rocks of Upper Indus Basin..........................................................17
4.2.4 Reservoir Rocks of Upper Indus Basin......................................................18
4.3 Lower Indus Basin.............................................................................................18
4.3.1 Central Indus Basin....................................................................................18
4.3.2 Source Rocks of Lower Indus Basin..........................................................19
4.3.3 Reservoir Rocks of Lower Indus Basin.....................................................19
4.4 Southern Indus Basin.........................................................................................20
5. Seismic Interpretation..................................................................................................21
5.1 Interpretation Workflow....................................................................................21
5.2 Marking of horizons..........................................................................................22

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5.3 Fault identification..............................................................................................22
5.4 Tie dip and strike lines.........................................................................................22
5.5 Time picking........................................................................................................23
5.6 Fault correlation...................................................................................................23
5.7 Time contour........................................................................................................23
5.8 Velocity picking...................................................................................................23
5.9 Depth contour.......................................................................................................23
6 Petrophysics.................................................................................................................24
6.1 Wireline Logs.......................................................................................................24
6.2 Types of Well logging........................................................................................25
6.2.1 Open Hole Logging......................................................................................25
6.2.2 Cased Hole Logging...................................................................................25
6.2.3 Production Logging....................................................................................26
6.2.4 Gamma Ray Logging..................................................................................26
6.2.5 Density Logging..........................................................................................26
6.2.6 Neutron Log................................................................................................26
6.2.7 Resistivity Log............................................................................................27
6.2.8 Laterolog Deep Resistivity (LLD) ............................................................27
6.2.9 Laterolog Shallow Resistivity (LLS) & Microspherically Focused Log...27
6.3 Petrophysical Interpretation................................................................................27
6.3.1 Volume of shale..........................................................................................28
6.3.2 Porosity Calculation....................................................................................28
6.3.3 Porosity from Density Log Data................................................................29
6.3.4 Effective Porosity.......................................................................................29
6.3.5 Water Saturation........................................................................................30
6.3.6 Saturation of Hydrocarbons.......................................................................30
7 Activities......................................................................................................................31
7.1 Stratigraphic Correlation....................................................................................31
7.2 Contours Map......................................................................................................31

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7.3 Geological Cross-section.....................................................................................31
7.4 Interpretation of Well Logs.................................................................................31
7.5 BASE MAP.........................................................................................................31
7.6 Geo- Seismic Section..........................................................................................31
List of Figures
Figures 1: G&G Activities of MPCL............................................................................8
Figures 2: Prospective Zones Maps (PPIS)...................................................................9
Figures 3: Exploration Cycle.......................................................................................10
Figures 4: Basins of Pakistan.......................................................................................17
Figures 5: Central Indus Basin.....................................................................................19
Figures 6: Southern Indus basin...................................................................................20
Figures 7: Seismic line.................................................................................................22
Figures 8: Depth contour.............................................................................................23
List of Tables
Table 1: Matrix Densities of Formations.....................................................................29
Annexures:
Annexure A: Stratigraphic Correlation
Annexure B: Isopach Map
Annexure C & D: Geological Cross-Section

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Acknowledgements
First of all I am very much grateful to Almighty Allah, who enabled me to complete
my internship successfully. A lot of Darood-o-Salam to the Holy Prophet Hazrat
Muhammad (S.A.W.W), who is the real source of wisdom, guidance, knowledge and
aspiration for the whole humanity. I wish to express my sincere and deep sense of
gratitude to my mentor, Waqar Ahmed Khan &Jawad Farooq, at Mari Petroleum
company limited Head Office Islamabad, who really helped me and accompanied me
all the time during the internship period for which I am indebted to them.
I wish to express my deepest regards to all respectable staff of exploration department
and human resources department specially Madam Anum and Madam Sana for
their kind and sincere guidance and moral support during my internship period.
I wish to express heartfelt thanks to my friends and all my other internship fellows for
their company and cooperation at the time of need. I will never forget their nice
behavior and versatile personalities.

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Introduction
Mari Gas Field was originally owned by Pakistan Stanvac Petroleum Project, a joint
venture formed in 1954 between Government of Pakistan and M/s Esso Eastern
Incorporated, having 49% and 51% ownership interest, respectively. The first gas
discovery was made by the Joint Venture in 1957 when the first well in lower Kirthar
‘Zone-B’ Limestone Formation was drilled. Production from the field started in 1967.
In 1983, M/s Esso Eastern transferred its entire share to Fauji Foundation, which set
up a public limited company for the purpose of acquiring the assets and liabilities of
the Project.
In 1984, Mari Gas Company Limited (MGCL) was incorporated with Fauji
Foundation, Government of Pakistan and OGDCL as its shareholders having 40%,
40%, and 20% shareholding, respectively. Upon formation, the Company took over
the assets, liabilities and operational control of Mari Gas Field. In 1985, the Company
commenced business in its own name and was given gas price through Mari Gas
Wellhead Price Agreement (Mari GPA).
In 1994, the Government divested 50% of its 40% shares and the Company became
listed on all the stock exchanges of Pakistan.
The Company primarily operated as a production company, developing in phases the
already discovered Habib Rahi Reservoir in Mari Gas Field for supply of gas to new
fertilizer plants. Simultaneously, the Company also pursued appraisal activities within
its Mari D&P Lease area by drilling step-out wells to determine the extent of Habib
Rahi Reservoir.
In 2001, the Company expanded its operations and entered into exploration business.
The Company is now a major player in the Country’s oil and gas exploration and
production sector operating eleven exploration and production assets (two D&P
leases and nine operated blocks) and has partnership with leading national and
international E&P companies in six non-operated blocks.
The Company also owns and operates a 3D seismic data acquisition unit, a 2D/3D
seismic data processing centre, three land drilling rigs and a slick line unit. With

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Expansion into exploration activities and addition of E&P allied services, MPCL has
become a fully integrated E&P company in Pakistan, having oil and gas fields in all
the provinces.
To reflect its diversified business operations and expanded activities, the name of the
Company was changed from “Mari Gas Company Limited” to “Mari Petroleum
Company Limited” (MPCL) in November 2012.
A major development during 2014 was approval of five year extension in Mari lease
period. This means that MPCL would enjoy the development and production rights in
the Lease Area till 2019. The extension will enable MPCL to enhance the recovery
and produce more natural gas which is critically needed in the Country.
Since its inception, the Company had been operating on a “cost-plus fixed return
formula” under Mari GPA 1985. Pursuant to consistent efforts by MPCL
Management, a major milestone was achieved in November 2014 when Economic
Coordination Committee of the Cabinet approved dismantling of Mari GPA and its
replacement with an international crude oil price linked market oriented formula.
Dismantling of Mari GPA would allow the Company to operate on commercial terms
and become competitive; thereby realizing its full potential.
In October 2015, the Company opted for conversion of Mari D&P lease to 2012
Petroleum Policy to avail the price incentives offered by the Government on
production enhancement initiatives.
In February 2016, MPCL became the first Pakistani E&P Company to implement its
incremental production project (Mari Field) and avail gas price incentive on
incremental field production offered in 2012 Petroleum Policy.

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Chapter 2
Overview of G&G/Exploration activities in MPCL
In addition to Mari Gas Field, MPCL currently holds Development & Production
Leases over Zarghun South and Sujawal Gas Fields and has operatorship of eight
exploration blocks (Ziarat, Harnai, Sukkur, Sujawal, Karak, Ghauri, Peshawar East,
and Khetwaro). The Company is also a non-operating joint venture partner with
leading national and international E&P companies in six exploration blocks (Kohlu,
Kalchas, Kohat, Zindan, Hala and Bannu West) and one D&P lease (Adam X). The
Company’s exploration and production assets are spread across the Country in all the
four provinces. As a distinct edge over many other E&P companies, MPCL owns and
operates a 3D seismic data acquisition unit, a 2D/3D seismic data processing centre,
three land drilling rigs and a slick line unit. With expansion into exploration activities
and addition of E&P allied services, MPCL has become a fully integrated E&P
company in the Country, rivaling the national oil company. MPCL started extensive
geological and geophysical exploration in 2001, often in partnerships with local and
international exploration and production companies to tap indigenous hydrocarbon
resources of the country. MPCL's success ratio is 1:1.4, which is high compared to
other E&P companies which average 1:4; internationally the ratio is 1:8. About 78%
of MPCL's gas production is dedicated to fertilizer plants, and the company is playing
a very critical role in the growth of the agriculture sector.
2.1 MPCL Operated Blocks
 Mari D&P Lease; MPCL has 100% working interest.
 Karak Block; MPCL has 60% working interest.
 Sukkur Block; MPCL has 58.8% working interest.
 Ziarat Block; MPCL has 60% working interest.
 Hanna Block; MPCL has 100% working interest.
 Harnai Block; MPCL has 40% working interest.
 Sujawal Block; MPCL has 100% working interest.
 Ghauri Block; MPCL has 35% working interest.

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 Zarghun South D&P Lease; MPCL has 35% working interest.
 Peshawar East; MPCL has 92.2% working interest.
 Khetwaro; MPCL has 51.5% working interest.
2.3 MPCL Non-operated Blocks
 Hala Block; MPCL has 35% working interest.
 Kohat Block; MPCL has 20% working interest.
 Kohlu Block; MPCL has 30% working interest.
 Bannu West; MPCL has 10% working interest.
 Zindan Block; MPCL has 35% working interest.
Figure 1: G&G Activities of MPCL

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2.4 Prospectivity Zones Maps (PPIS)
There are three zones of prospect
Zone 1
High risk and high cost zone
Zone 2
Medium risk and high cost
Zone 3
Low risk and low to medium cost
COLOR CODE
 ZONE 1 =ORANGE
 ZONE 2 =YELLOW
 ZONE 3 =PINK
 Zone O= Offshore (BLUE)
Figure 2: Prospectivity Zones Maps (PPIS)

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Chapter 3
Exploration Cycle
Figure 3:Exploration Cycle

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3.1 Block Evaluation:
Block: It is the area granted by DGPC to any E&P company to carryout exploration
activities. The block will have specific area and co-ordinates. Initially, the block
granted for three years.
G&G Data: G&G data stand for geological & Geophysical data.
Farm-in: It refers to partnership i.e. purchase of some percentage of working
interests in a block operated by any other E&P company. Usually, a company invites
other E & P companies to review the technical data of lock after signing the
confidently agreement and subsequent to review / detailed evaluation,
recommendations are submitted to farm-in the block or otherwise.
Fram-out: It refers to selling out of some percentage of working interests of an
operated block to other E&P company.
Usually, interested E & P companies are invited to review the data of block after
signing the confidante agreement to dilute working interest and to share risk in an
operated block.
3.2 Block Carve out: It is the marking of the block from an open area based on
detailed G&G evaluation. Application along with co-ordinates of the curved out block
to acquire its exploration rights is submitted to DGPC.
3.3 Block Bidding
Directorate General of Petroleum Concessions (DGPC): DGPC is the
Government regulatory authority for E&P activities in Pakistan."Director General of
Petroleum Concessions" means any officer appointed by the government to exercise
the powers and perform the functions of the Directorate under the prevailing Rules.
Exploration License(EL): EL means exploration license of the block granted by
government of Pakistan to carryout Hydrocarbon Exploration / exploitation activities.
Exploration License Application: It is the application submitted by the
company to DGPC to acquire Exploration License of the block.

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Work Commitment: It is the minimum work / finances committed to DGPC
against Exploration license of the block. Usually, work is committed in terms of
number of wells up to certain depths, 2D/3D surveys and their processing &
interpretation or financial cost.
Work Units (W.U): It is the conversion of the work program into numbers which
is committed to DGPC against Exploration license of the block at the time of bidding.
Work units are only discharged against drilling of wells & 2D/3D seismic data
acquisition.
Bid Document: This document is an offer of minimum work/financial
commitment by the company to DGPC against exploration license of a particular
block at the time of bidding. The companies with highest offer are granted with
exploration rights of that particular block.
Past Cost: It is the exploration and development cost as of today borne by the
operation company of the license
3.4 Block Award
Petroleum Concession Agreements ( PCA ): A petroleum concession
Agreements (PCA) is a negotiated contract between a company and governments that
gives the company the rights to operate a petroleum business within the
government’s jurisdiction, subject to certain conditions.
Joint Operating Agreement (JOA): Joint operating agreement (JOA) is a
contract where two or more parties agree to undertake a common task to explore and
exploit an area for Hydrocarbons. The parties to the agreements can be broadly
classified as operators and non-operators. The operator is the one who is responsible
for the day-to-day management and operation of the field.
Farm-out Operating Agreement (FOA): In the oil and gas industry, a farm-
out operating agreement is an agreement entered into by the owner of one or more
mineral leases, and another company who wishes to obtain a percentage of ownership
of that lease or leases in exchange for providing services.

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Corporate Social Responsibility (CSR): CSR refers to business practices
involving initiatives that benefit society where the company is conducting E&P
activities.
Development& Production Licence (D&PL): D&PL means development
& production license of the area to carryout development activities. Once a
commercial discovery is made in an E.L..,then companies declare its commerciality
and ask DGPC to grant D&P.L of that particular discovery area within E.L,boundary
to carry our exploitation of Hydrocarbons.
No Objection Certificate (NOC): No objection certificate (NOC) is issued by
concerned authorities to carry out any activity. Different kind of N.O.C is required
from concerned authorities for conducting different E&P activities in the block. For
example, IEE, security, explosive usage /transportation, expatriate movement N.O.Cs
etc.
Block Relinquishment: It is release/removal of the whole or part of the block
from any company's existing portfolio.
3.5 Reserves
Resource: Resource are hydrocarbons which may or may not be produced in the
future. A resource number may be assigned to an undrilled prospect or an un-
appraised discovery.
Reserves: Oil and gas reserves are defined as volumes that will be commercially
recovered in the future. Reserves are separated into three categories: Proved,
probable, and possible. Technical issues alone separate proved from unproved
categories. All reserve estimates involve some degree of uncertainty.
Proved reserves are the highest valued category. Proved reserves have a "reasonable
certainly" of being recovered, which means a high degree of confidence that the
volumes will be recovered. Some industry specialists refer to this as P90, i.e., having
a 90% certainty of being produced.

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Probable reserves are volumes defined as “less likely to be recovered than proved,
but more certain to be recovered than possible Reserves" .Some industry specialists
refer to this as P50, i.e., having a 50% certainly of being produced.
Possible reserves are reserves which analysis of geological and engineering data
suggests are less likely to be recoverable than probable reserves. Some industry
specialists refer to this as P10, i.e., having a 10% certainty of being produced.
The term 1P is frequently used to denote proved reserves; 2P is the sum of proved and
probable reserves and 3P the sum of proved, probable, and possible reserves. The best
estimate of recovery from committed projects is generally considered to be the 2P
sum of proved and probable reserves. Note that these volumes only refer to currently
justified projects or those projects already in development.
Recoverable Reserves (Gas, Condensate or Oil): It is the portion of
reserves that can be recovered to the surface by currently available technologies.
Recovery Factor: It is the percentage of hydrocarbon in place that can be
produced with each production plan: Primary, secondary and tertiary.
3.6 Budget
Carried Forward Budget: It is the budgetary value which could not be utilized
during agreed year and is shifted to next year in-order to carry out the same head
activity.
Authority for expenditures (AFE): Preparing cost estimates for a well and
getting management approval is the form of an AFE is the final step in well planning.
The AFE is often accompanied by a projected payout schedule or revenue forecast.
Circular Resolution (C.R ): Circular resolution is a mechanism that allows the
operator company to pass a resolution without a meeting among its joint venture
partners. They are commonly used for non-contentious and routine resolution that
needs to be passé between board meetings.
Joint venture (JV): Joint venture which is commonly abbreviated as "JV" is a
business arrangement in which two or more parties agree to pool their resources for

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the purpose of accomplishing a specific task. In E&P sector, it refers to a block whose
working interests are owned by two or more companies. IN JV blocks, one company
acts as operator and is responsible for all activities of the block in consensus with
joint venture partners (JVP).
Technical Committee Meeting ( TCM ): "Technical Committee Meeting"
usually abbreviated as "TCM" is a forum wherein joint venture partners (JVP) discuss
and agree work program me of any exploration block and recommend it to Operated
committee Meeting "OCM" for approval. TCM/OCM is a legal forum and is
obligatory to be held once in a quarter as per petroleum concession Agreement (PCA)
and joint Operating Agreement (JOA).
Operating committee Meeting (OCM):"operating Committee Meeting"
usually abbreviated as "OCM" is a forum wherein joint venture partners (JVP)
approve work program recommended by TCM and budget of any exploration
block.TCM/OCM is a legal forum and is obligatory to be held once in a quarter as per
Petroleum Concession Agreement(PCA) and Joint Operating Agreement (JOA).
Finance Committee Meeting (FCM):"Finance committee Meeting" usually
abbreviated as "FCM" is a forum wherein joint venture partners (JVP) discuss all
financial matters and budget of the block.
Technical Workshop (TW): Technical workshop (TW) is a forum where in
joint venture partners discuss the technical matters of any on-going activity or
planning of future activities and develop consensus. Technical workshop is not a legal
forum and its recommendations need to be legalized through OCM. A Technical
workshop can be arranged any time on need basis.

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Chapter 4
Basins of Pakistan
On the bases of genesis and different geological history, Pakistan is mainly divided
into mainly two sedimentary basins which involved through different geological
episodes and were finally welded together during Cretaceous/Paleocene age along
with chaman strike slip fault.
 Indus Basin
 Baluchistan Basin
Pishin basin is also known as 3rd basin of Pakistan which carries its own geological
history his basin came into existence due t interaction of Indian and Eurasian plates.
4.1 Indus Basin
The geological history of the Indus basin goes back to Precambrian age its features also
marked the limit of the basin and its division. Indus basin mainly divided into two parts which
are briefly discussed below:
 Upper Indus basin
 Lower Indus basin
4.2 Upper Indus basin:
The upper Indus basin is located in northern Pakistan and it is separated from the
lower Indus basin by Sargodha high. The northern and eastern boundaries coincide
with the main boundary thrust (MBT) and the western boundary is marked by an
uplift of pre Eocene which are eastern ward thrusted in the west of bannu.
4.2.1 Kohat Basin
4.2.2 Potwar Basin
All though theses two basin are small in size but they depict important facies
variation. Potwar sub basin preserves the sediment from Precambrian to Quaternary
age in the subsurface and of these are exposed in salt Range thrust. The Trans Indus
ranges in the South and Kohat sub basin which exposed sediments from Cambrian to

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Pliocene age. And both Kohat and Potwar sub basin are characterized by an
unconformity between Cambrian and Permian age. The Kohat and Potwar basin is
separated by Indus River.
Figure 4: Basins of Pakistan
4.2.3 Source Rocks of Upper Indus Basin:
• In Potwar, Patala Shale of Paleocene are Primary source rock.

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• In Kohat, probably Chichali Formation (Lower cretaceous) considered as
source rock
• Mianwali Formation (Lower Triassic)
• Dondot Formation (Early Permian)
• Sarddhai Formation (Early Permian)
4.2.4 Reservoir Rocks of Upper Indus basin:
• Warcha Formation (Early Permian)
• Wargal formation (Permian)
• Lokhart Formation (Paleocene)
• Chorgali Formation (Eocoene)
• MureeFormation (Miocene)
• Sakessar
• Khewra
• Tobra
• Datta
• Samana Suk
• Hangu/Lumshiwal
4.3 Lower Indus basin:
Different classification schemes have been given to this basin on the bases of various
expects. The lower Indus basin is mainly divided into two parts Central Indus basin
and southern basin.
4.3.1 Central Indus Basin:
Central Indus basin is further divided in two three main parts which are
a. Punjab Platform.
b. Sulaiman Depression.
c. Sulaiman Fold belt

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Figure 5: Central Indus Basin
The boundary between Central Indus basin and upper Indus basin is Sargodha high
and central Indus basin is separated from southern Indus basin by Sukker rifts and the
east side of central Indus basin is bounded by Indian shield and on the west side of
the basin marginal zone of Indian plate is present. The oldest rock exposed in this
basin is of Triassic age which is Wulgai formation while the oldest rock penetrated
through drilling are of Precambrian age which is salt range formation on Punjab
platform. The depth to the basement is about 15000 meter in the trough areas.
4.3.2 Source Rocks of Lower Indus basin
• Sembar Shale (Early cretaceous) widely accepted as main source rock
4.3.3 Reservoir Rocks of Lower Indus basin
• Pab/Mughalkot sandstone (Maestri chtian)
• Lower Guru Formation (Lower Cretaceous)

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4.4 Southern Indus Basin:
Southern Indus basin is further divided in five main units which are following
a. Thar Platform.
b. Karachi Trough.
c. Kirther Foredeep
d. Kirther Fold Belt.
e. Offshore Indus.
Figure 6: Southern Indus Basin
The Southern Indus basin is located in the south of Central Indus basin and the
boundary between Central and Southern Indus basin is sukker rift. The southern Indus
basin is bounded by Indian shield to the east and on the west side it is bounded by
marginal zone of Indian plate and its southward extension is confined by offshore
Murray Ridges oven fracture plate boundary. The oldest rocks encountered in this
area are of Triassic age. Lower Indus basin and southern Indus basin are undivided
until lower /middle Cretaceous when Khairpur Jacobabad highs are prominent
positive features; this is indicated by homogeneous lithologies of chiltan limestone of
Jurassic and sembar formation of lower cretaceous across the high.

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Chapter 5
Seismic Interpretation
The final step after the processing is interpretation. Once the data is processed it is
read for the interpretation. The aims of seismic interpretation are to recognize
subsurface geology. The interpreter must now about the geology as well as
acquisition and processing parameters. The seismic record contains two basic
elements for the interpreter to study. The first is the time of arrival of any reflection
(or refraction) from a geological surface. The actual depth to this surface is a function
of the thickness and velocity of overlying rock layers. The second is the shape of the
reflection, which includes how strong the signal is, what frequencies it contains, and
how the frequencies are distributed over the pulse. This information can often be used
to support conclusions about the lithology and fluid content of the seismic reflector
being evaluated.
5.1 Interpretation Workflow
Synthetic Seismogram:
Once a stratigraphic model has been built using velocities and densities, a synthetic
seismogram (or synthetic) can be constructed to identify seismic reflections. A
synthetic seismogram is the fundamental link between well data and seismic data, and
it is the main tool (along with a vertical seismic profile, that allows geological picks
to be associated with reflections in the seismic data. As discussed, if a VSP is
available for a particular well, a synthetic is not needed. The VSP directly measures
both time and depth to a formation of interest. Usually synthetic seismograms are
created using specialized software. The user may be unaware of the process that
creates them. The steps necessary to create a synthetic seismogram manually are
described below:
Edit the sonic and density logs for bad intervals.
Calculate vertical reflection times.
Calculate reflection coefficients, Ro

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1. Combine the last two items to create a reflection coefficient time series.
2. Convolve the reflection coefficient series with the wavelet.
Figure 7: Seismic Line
5.2 Marking of horizons:
Horizons on the seismic section are identified they are usually visible as high intense
reflector on seismic section. Based on the knowledge of seismic data each horizon is
marked on the seismic data
5.3 Fault identification:
Faults are marked on the seismic section which identified the breakage in the strata.
The reflector shows faults as disturb horizon

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5.4 Tie dip and strike lines:
The dip line (denoted as line) and strike line (denoted as trace) are tie. Fold the
seismic section at line number at which we want to tie and place it on strike line at the
same number.
5.5 Time picking:
Time of each horizon and fault are picked from both strike and dip lines and are
plotted at base map.
5.6 Fault correlation:
After time plotting on the base, faults are correlated of each dip lines.
5.7 Time contour:
Contours of same point are join to form time contour.
5.8 Velocity picking:
Velocities are picked at each point of the horizon.
5.9 Depth contour:
Finally, depth contour map is generated using velocities and time contour map.
Figure 8: Depth Contour Map

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Chapter 6
Petrophysics
Petrophysics is basically the branch of geology that is concerned with the study of
physical and chemical rock properties and their interactions with fluids. Its major
application is to study reservoir properties for Hydrocarbon industry. Petrophysics
emphasizes on those properties that are related to the pore system and distribution and
flow of its fluids. Such properties and their relationships are used to identify and
evaluate hydrocarbon reservoirs, hydrocarbon sources, seals and aquifers. Key
properties that are studied in Petrophysics are
 Lithology
 Porosity
 Water saturation
 Permeability
 Density
6.1 Wireline Logs
Wireline logging is used to obtain a continuous record of a formation's rock
properties through which the well is drilled. It is performed by lowering a logging
tool or a string of one or more instruments on the end of a wireline into a borehole
and recording petrophysical properties using a variety of sensors. Wireline logs are
also called well logs. Many types of well logs are present and are used according to
the characteristics of rocks that are needed to be measured. The main purpose of well
logging is to provide data for evaluating petroleum reservoirs and aid in testing,
completion and repairing of the well.
6.2 Types of Well logging
Well logging is classified into three broad categories:
1. Open hole logging
2. Cased hole logging
3. Production logging

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6.2.1 Open Hole Logging
Open hole logging refers to logging operations that are performed on a well before
the wellbore has been cased and cemented. This is the most common type of logging
method because the measurements are not obstructed and it is done during or after the
well has been drilled. Electrical surveys, radioactive surveys, sonic logs and dip meter
logs are used in open hole logging.
6.2.2 Cased Hole Logging
Cased hole logging refers to logging measurements through the well casing or the
metal piping that during the completion operation is injected into the well. Gamma
Ray log, neutron log, cement bond log and tracer log surveys are performed in this
type of logging. Cased hole logging is rarely performed but it provides valuable
information about the well.
6.2.3 Production Logging
Production Logging refers to the services that include cement monitoring, corrosion
monitoring, monitoring of formation fluid contacts, perforating and plug and packer
setting. Neutron logs, gamma ray logs, density logs and resistivity logs are used in
production logging. Production logs are used to allocate production on a zone by zone
basis and also to diagnose production problems such as leaks or cross flow.
6.2.4 Gamma Ray Logging
The Gamma ray log is the measurement of natural radioactivity of the formations. As
the radioactive elements tend to concentrate in shales and clays so if in the subsurface
sedimentary formations like shale and clays are encountered the log trend deflects
towards right and gives us high GR value whereas if clean formations are
encountered the log trend will deflect towards left indicating a very low level of
radioactivity. The gamma ray logs are useful for obtaining a correlation curve when
used in cased wells.
6.2.5 Density Logging
Density log provides a continuous record of a formation's bulk density for
determining total porosity of the formation along the length of a borehole. Density

27
logs are used for identification of minerals in evaporate deposits, recognition of
accessory mineralogies, shale compaction, detection of gas, determination of
hydrocarbon density, fracture recognition and complex lithologies, determination of
oil-shale yield, calculation of overburden pressure and rock mechanical porosities.
Density logs are also termed as porosity logs.
6.2.6 Neutron Log
Neutron logs are used principally for delineation of porous formations and
determination of their porosity. They respond primarily to the amount of hydrogen in
the formation which is mostly present in oil, gas and water. Thus, in clean formations
whose pores are filled with water or oil, the neutron log reflects the amount of liquid-
filled porosity. Gas zones can often be identified by comparing the neutron log with
another porosity log. Combination of neutron log with other porosity logs yields even
more accurate porosity values and lithology identification.
6.2.7 Resistivity Log
Resistivity log 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 log
evaluation the resistivity of the formation is the principal indicator of hydrocarbons
therefore emphasis has been put on the precise determination of resistivity values.
Following surveys are used in resistivity log.
6.2.8 Laterolog Deep Resistivity (LLD)
Laterolog emit focusing currents to direct the path of the measured current through
the mud and the invaded zone to the uninvaded zone. They reduce the effects of the
borehole, adjacent formations and thin beds, but are still affected by hole diameter,
mud resistivity and very thin formations with high resistivity contrast.
6.2.9 Laterolog Shallow Resistivity (LLS) & Microspherically
Focused Log (MSFL)
The dual laterolog (DLL) consists of two advanced laterolog tools, which share the
same electrodes on the primary sonde. One laterolog is used for deep investigation of

28
the undisturbed zone (Rt) and the other for shallow investigation of the transition
zone (Ri).
6.3 Petrophysical Interpretation
It is necessary to know the thickness of oil bearing formation, hydrocarbon saturation,
and lateral extent of the reservoir and porosity of formation to calculate the volume of
recoverable hydrocarbon in a reservoir.
6.3.1 Volume of shale
The Gamma ray log is particularly useful for defining shale beds. The Gamma ray log
reflects the proportion of shale and in many regions can be used quantitatively as a
shale indicator and also a best bed marker. Gamma ray log also separates the clean
and dirty zone. In the quantitative evaluation of shale content volume of shale was
calculated by using the formula below:

29
Where, V sh = Volume of shale
GR log = GR log reading at specific point (API Unit)
GR min = Gamma Ray minimum across interval (API Unit)
6.3.2 Porosity Calculation
Porosity can be defined as the ratio of voids to the total volume of rock. It is
represented as a decimal fraction or as a percentage and is usually represented by the
Greek letter ф (phi). Mostly the combination of density and neutron logs is used
commonly as a means to determine porosity that is largely free of lithology effects. A
sonic log is also used for porosity calculation and is a recording against the depth of
the travel time of high frequency acoustic pulses through formation close to the
borehole.
6.3.3 Porosity From Density Log Data:
Formation bulk density (φ den) is a function of matrix density, porosity, and density
of the fluid in the pores (salt, mud, fresh mud, or hydrocarbons). The formula for
calculating density porosity is:
φ den = (ρma-ρb)/ (ρma-ρf)
Where: φ den = Density derived porosity
ρma = Matrix density
ρb = Formation bulk density
ρf = Fluid density

30
The matrix densities of some of the formations are given in the table below:
Lithologoy ρma(gm/cm3
)
Sandstone 2.648
Limestone 2.710
Dolomite 2.876
Anhydrite 2.977
Salt 2.032
Shale 2.2 – 2.25
6.3.4 Effective Porosity
It is the sum of all the interconnected pore spaces. In the vast majority of cases, this
core analysis and Petroleum Engineering definition of effective porosity equates to
total porosity. The Effective porosity can calculate from the following formula:
φ eff = Porosity avg *(𝟏 − 𝐕𝐬𝐡𝐥)
Where: φ eff = Effective porosity
φ avg =Average porosity
Vshl =Volume of shale
V sand = Volume of sand (which is = 1 − Vshl)
6.3.5 Water Saturation
During the log analysis of well Water Saturation (Sw) is calculated with the help of
Archie Equation.
Where:
Sw = Water Saturation
n = Saturation Exponent
a = Lithological Coefficient
Ф= Porosity
m = Cementation factor

31
Rw = Resistivity of water
Rt = True Resistivity (Deep Resistivity) at that or depth.
The values of m, n and a come from the core analysis of the data. We assume these
three values to be constant.
n = 2
m = 1
By putting values of theses parameters and simplifying the above equation it becomes
as follows: Sw
Now Sw values are calculated by using above formula.
6.3.6 Saturation of Hydrocarbons
Saturation of hydrocarbons is calculated by using formula which is 1-Sw. After that
the values which come we multiply with 100 to represent in percentage. Saturation of
Hydrocarbons and Saturation of Water graphs are inverses of each other.

32
Chapter 7
Activities
Various exercises and activities were carried throughout the course of the internship,
for better understanding and assimilation of practices in the exploration industry. All
of tasks were carried out under the guidance and supervision of the respective
mentors. A number of these activities have been attached in the annexure at the end of
this report, while a few have been left out due to the confidential nature of the data.
The exercises carried out include the following:
 Stratigraphic Co- relation.
 Contours Map.
 Geological Cross-section.
 Interpretation of Well Logs.
 Base map.
 Geo- Seismic Section.
7.1 Stratigraphic Co- relation
In stratigraphic co-relation of Sujjawal-1, Nur-1 and Dari-1 we co-related stratigraphy
of different wells.
Activity is attached as Annexure: A.
7.2 Contours Map
Isopach map of Sandstone has been made using triangular method.
Activity is attached as Annexure: B.
7.3 Geological Cross-section
Geological cross section along line AB has been made and identification of syncline
in subsurface has been identified; although anticline has been eroded. Activity is
attached as Annexure: C&D.

33
7.4 Interpretation of Well Logs
Volume of hydrocarbon has been calculated and other Petro-physical properties such
as porosity and permeability has been identified using Resistity log, Density log,
Neutron log, Gamma Ray Log and Sonic Log.
7.5 Base Map
Base map is a map on which primary data and interpretations can be plotted. A base
map typically includes locations of lease or concession boundaries, wells, and seismic
survey points with a geographic reference such as latitude and longitude.
7.6 Geo- Seismic Section
Cross section of Depth map of Lower Goru has been made and structure of different
faulted and folded formations has been identified subsurface, based on the depth
contour maps, lithologies has been marked according to the given information.

34
REFERENCES
Iqbal Qadari , I. Q., 1995. Petroleum Geology of Pakistan.
Kazmi, A. H., 1977. Review of the Quaternary Geology of the Indus Plain.
Molnar, P., 1986. The geologic history and structures, Am. Sci., Vol. 24.
Powell, C. M. (1979): A speculative tectonic history of Pakistan and surrounding:
Some constraints from the Indian Ocean.
Iqbal Qadari , I. Q., 1995. Petroleum Geology of Pakistan.
MPCL, Glossary of terms, Oil and Gas Industry.
.

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