Patala-Nammal Composite Total Petroleum System,

Kohat-Potwar Geologic Province, Pakistan

By C.J. Wandrey, B.E. Law, and Haider Ali Shah

U.S. Geological Survey Bulletin 2208-B

U.S. Department of the Interior

U.S. Geological Survey

Petroleum Systems and Related Geologic 

Studies in Region 8, South Asia

Edited by Craig J. Wandrey
U.S. Department of the Interior

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

This publication is only available online at:

http://pubs.usgs.gov/bul/b2208-b/

Posted online February 2004, version 1.0
Foreword

This report describing the petroleum resources within a total petroleum system 

in Pakistan was prepared as part of the World Energy Assessment Project of the U.S. 

Geological Survey. For this project, the world was divided into 8 regions and 937 

geologic provinces, which were then ranked according to the discovered oil and gas 

volumes within each (Klett and others, 1997). Of these, 76 “priority” provinces (exclusive 

of the United States and chosen for their high ranking) and 26 “boutique” provinces 

(exclusive of the United States and chosen for their anticipated petroleum richness 

or special regional economic importance) were selected for appraisal of oil and gas 

resources. The petroleum geology of these priority and boutique provinces is described in 

this series of reports.

The purpose of the World Energy Project is to assess the quantities of oil, gas, and 

natural gas liquids that have the potential to be added to reserves within the next 30 

years. These volumes either reside in undiscovered fi elds whose sizes exceed the stated 

minimum-fi eld-size cutoff value for the assessment unit (variable, but must be at least 1 

million barrels of oil equivalent) or occur as reserve growth of fi elds already discovered. 

The total petroleum system constitutes the basic geologic unit of the oil and gas 

assessment. The total petroleum system includes all genetically related petroleum that 

occurs in shows and accumulations (discovered and undiscovered) and that (1) has been 

generated by a pod or by closely related pods of mature source rock, and (2) exists within 

a limited, mappable geologic space, along with the other essential, mappable geologic 

elements (reservoir, seal, and overburden) that control the fundamental processes of 

generation, expulsion, migration, entrapment, and preservation of petroleum. The 

minimum petroleum system is that part of a total petroleum system encompassing 

discovered shows and accumulations along with the geologic space in which the various 

essential elements have been proved by these discoveries.

An assessment unit is a mappable part of a total petroleum system in which 

discovered and undiscovered fi elds constitute a single, relatively homogenous population 

such that the chosen methodology of resource assessment based on estimation of the 

number and sizes of undiscovered fi elds is applicable. A total petroleum system may 

equate to a single assessment unit, or it may be subdivided into two or more assessment 

units if each unit is suffi ciently homogeneous in terms of geology, exploration 

considerations, and risk to assess individually.

A graphical depiction of the elements of a total petroleum system is provided in the 

form of an event chart that shows the times of (1) deposition of essential rock units, (2) 

trap formation, (3) generation, migration, and accumulation of hydrocarbons, and (4) 

preservation of hydrocarbons. 

A numeric code identifi es each region, province, total petroleum system, and 

assessment unit; these codes are uniform throughout the project and will identify the 

same type of entity in any of the publications. The code is as follows: 

Example 

 Region, single digit 2

 Province, three digits to the right of region code 2004

 Total petroleum system, two digits to the right of province code 200401

 Assessment unit, two digits to the right of total petroleum system code 20040101
The codes for the regions and provinces are listed in Klett and others (1997).

Oil and gas reserves quoted in this report are derived from Petroconsultant’s 

Petroleum Exploration and Production database (Petroconsultants, 1996) and other area 

reports from Petroconsultants, Inc., unless otherwise noted.

Figure(s) in this report that show boundaries of the total petroleum system(s), 

assessment units, and pods of active source rocks were compiled using geographicinformation-system (GIS) software. Political boundaries and cartographic representations 

were taken, with permission, from Environmental Systems Research Institute’s ArcWorld 

1:3,000,000 digital coverage (1992), have no political signifi cance, and are displayed 

for general reference only. Oil and gas fi eld center points, shown on these fi gures, are 

reproduced, with permission, from Petroconsultants (1996). 
Contents

Foreword ....................................................................................................................................................... iii

Introduction ................................................................................................................................................... 1

Acknowledgments........................................................................................................................................ 1

Regional Geologic History........................................................................................................................... 1

Stratigraphy ................................................................................................................................................... 8

Production History........................................................................................................................................ 9

Composite Petroleum System................................................................................................................... 10

Source Rock ....................................................................................................................................... 10

Maturation .......................................................................................................................................... 11

Generation and Migration ................................................................................................................ 12

Reservoir Rocks ................................................................................................................................. 13

Traps and Seals.................................................................................................................................. 14

Assessment Unit ................................................................................................................................ 14

Assessment of Undiscovered Oil and Gas ............................................................................................. 14

Summary ...................................................................................................................................................... 17

Selected References.................................................................................................................................. 19

Figures

 1. Map showing location of the Kohat-Potwar geologic province........................................... 2

 2. Generalized geology of the Kohat-Potwar geologic province and surrounding area ...... 3

 3. Generalized structure of Kohat-Potwar geologic province area ......................................... 4

 4. Extent of total petroleum systems in the Kohat-Potwar geologic province area.............. 4

 5. Generalized stratigraphy of the Kohat-Potwar area .............................................................. 5

 6.–11. Paleogeographic maps of the:

 6. Middle Jurassic (approximately 166 Ma) ...................................................................... 6

 7. Early Cretaceous (approximately 130 Ma)..................................................................... 6

 8. Late Cretaceous (approximately 94 Ma)........................................................................ 6

 9. Latest Cretaceous (approximately 69 Ma)..................................................................... 6

 10. Middle Eocene (approximately 50 Ma) .......................................................................... 7

 11. Late Oligocene Epoch (approximately 27 Ma) .............................................................. 7

 12. Generalized cross section showing structure through the Potwar Plateau ...................... 7

 13. Generalized oil and (or) gas field and structure map of Kohat-Potwar area ..................... 8

 14. Plot showing the cumulative number of new-field wildcat wells versus 

well-completion year ................................................................................................................. 10

 15. Maturity of exploration indicator plots showing known and grown 

(expected final size when production is ended) field sizes grouped in 

thirds by age of discovery and ranked by size ...................................................................... 11
 16. Plots showing cumulative known and grown oil volumes versus 

the cumulative number of new-field wildcat wells............................................................... 12

 17. Plot showing field size versus field-discovery year ............................................................. 13

 18. Plot showing reservoir depth versus oil-field-discovery year............................................ 13

 19. Generalized cross section showing structure through the Potwar Plateau .................... 14

 20. Generalized burial-history plots for the ODGC Dakhni 1 well and the 

Gulf Oil Fim Kassar well ............................................................................................................. 15

 21. Distribution of producing reservoirs by age and number of fields 

in which they occur.................................................................................................................... 16

 22. Distribution of producing reservoirs by age, lithology, and number 

of fields reporting production from that age group and lithology type.............................. 16

 23. Petroleum system events chart for the Kohat-Potwar geologic province ....................... 18

Tables

 1. Estimates of undiscovered oil and gas for the Patal-Nammal composite 

total petroleum system, Kohat-Potwar geologic province (8026), Pakistan..................... 17

 2. Expected size distribution for undiscovered oil fields in the Kohat-Potwar 

geologic province ....................................................................................................................... 17

 3. Expected size distribution for undiscovered gas fields in the Kohat-Potwar 

geologic province ....................................................................................................................... 18
Introduction

Among the 26 boutique provinces identifi ed for the World 

Energy Assessment Project was an onshore, oil-prone area 

named the Kohat-Potwar geologic province (fi g. 1). The province (part of the upper Indus Basin) is bounded on the north 

by the Parachinar-Murree fault, on the west by the Kurram 

fault, on the south by the Surghar and Salt Ranges, and on 

the east by the Jehlum fault (fi gs. 2 and 3). The area includes 

the Potwar and Kohat Plateaus and Bannu Depression. The 

Kohat-Potwar province consists of a portion of the Indian 

plate structurally deformed by plate collision and overthrust 

of the Himalayas on the north and northwest. Important structural features (fi g. 3) include a series of faulted and unfaulted 

anticlines developed on multiple detachment surfaces as deep 

as Cambrian and thrust faults that trend generally southwestnortheast parallel to the plate-collision boundary. 

Acknowledgments

Most of the data presented in this report was provided by 

the Oil and Gas Development Corporation (OGDC), Islamabad, Pakistan, and Amoco Production Co., Houston, Texas. 

We are especially grateful to Mr. Marten James of Amoco for 

his help in obtaining geologic data from Pakistan. 

The authors thank technical reviewers E.A. Johnson and 

Peter Warwick for their valuable suggestions and insight. 

Regional Geologic History

The total petroleum system (TPS) and assessment unit 

(AU) discussed herein (fi g. 4) acquired their primary structural 

and stratigraphic features from events associated with plate 

movements that occurred from latest Paleozoic to the present. From Permian through Middle Jurassic time, the Indian 

plate was located in the Southern Hemisphere—between the 

African, Antarctic, and Australian plates—and comprised part 

of southern Gondwana. The Lower Permian Tobra Formation tillites (fi g. 5) in the Kohat-Potwar area and other basal 

Permian glacial deposits on the Indian plate are indicative of 

a much cooler paleoclimate (Shah and others, 1977). The area 

that is now the Indus Basin, Kohat-Potwar geologic province, 

and northern India, was a shallow continental shelf on which 

carbonates, shales, and sandstones were deposited. This carbonate-dominated environment persisted at least intermittently 

on the western part of the shelf through the Late Jurassic and 

is represented by the interbedded shales and thick limestones 

of the Springwar Formation and as much as 1,400 m of the 

Middle and Upper Jurassic Sulaiman Limestone Group on 

western and northern portions of the plate. In the area that 

is now the Kohat-Potwar geologic province, shelf and shallow-marine stages are preserved in the rocks of the Permian 

Nilawahan, Permian and Triassic Zaluch, Triassic Musa Khel, 

and Jurassic and Cretaceous Surghar Groups. During the 

Late Jurassic, Madagascar, India, Australia, Antarctica, and 

the Seychelles began to break away from Africa, forming the 

Somali Rift Basin (fi gs. 6 and 7). Late Jurassic rifting also initiated separation of Australia and Antarctica from India.

During Early Cretaceous time, the Indian plate drifted 

northward, entering warmer latitudes. Along the eastern portion of the Indian plate, the Rajmahal Trap volcanics were 

deposited. On the northwest margin of the plate, marine 

shales and limestones of the Lower Cretaceous Sembar and 

Goru Formations were deposited over a regional erosional 

surface on the Sulaiman Group. In the Kohat Potwar area, 

this erosional surface is present at the top of the Samana Suk 

Formation and is overlain by sandstones and shales of the 

Lower Cretaceous Chichali Formation. On the eastern shelf 

of the Indian plate, the Bolpur and Ghatal Formations were 

deposited. Whereas carbonates are recognized primarily on 

the eastern and western shelves today, it is likely that they 

were deposited over much of the northern shelf as well. This 

shelf environment persisted through the Late Cretaceous when 

regressive sandstones such as the Lumshiwal and Pab Formations in the west and Tura Formation in the east were deposited. During the latest Cretaceous, the Indian plate continued 

to drift northward toward the Eurasian plate and the seafl oor of 

Patala-Nammal Composite Total Petroleum System, 

Kohat-Potwar Geologic Province, Pakistan

By C.J. Wandrey,1 B.E. Law,2 and Haider Ali Shah3

1

 U.S. Geological Survey, Denver, Colorado.

2

 Consultant, Lakewood, Colorado.

3

 Oil and Gas Development Corporation, Ltd., Islamabad, Pakistan. 

1
the Bengal Basin began to form and fl ysch accumulated on all 

sides of the Indian plate (fi g. 8). 

Northward plate movement continued during the Late 

Cretaceous, and a transform fault became active along the 

Ninety-East Ridge (fi g. 9). Rifting between Madagascar and 

the Seychelles portion of the Indian plate initiated formation 

of the Mascarene Basin. Extensional faulting occurred as the 

western part of the Indian plate sheared southward relative to 

the main plate (Kemal and others, 1992). Counterclockwise 

rotation of the Indian plate was initiated, and the Seychelles 

portion of the Indian plate began to break away (Waples and 

Hegarty, 1999) (fi g. 9). 

Latest Cretaceous was also a time of intense volcanism in 

western India, with the expulsion of the Deccan Trap basalts 

and further rifting, which began, and then failed, leaving the 

Cambay and Kutch Grabens fl oored with the Deccan Trap 

basalts (Biswas and Deshpande, 1983). The rifting event in the 

Cambay and Kutch areas might be related to the extensional 

faulting and shear zone that was developing at the same time 

in the Indus Basin. 

From the Late Cretaceous through middle Paleocene, trap 

deposits and basal sands continued to accumulate on the western, northern, and eastern shelves of the Indian plate (fi g. 10). 

Oblique convergence of the Indian plate with the microplates 

constituting the southern edge of the Eurasian plate resulted 

in wrench faulting and development of regional arches such 

as the Jacobad and Sargodha Highs in the Indus Basin (fi g. 2) 

(Kemal and others, 1992). 

The Indian plate continued to move northward at an 

accelerated rate of 15–20 cm/yr (Scotese and others, 1988). 

When the eastern edge of the plate passed over the Kerguelen hot spot, a chain of islands began to form near long 

90°E. Continued northward movement and counterclockwise 

rotation of the Indian plate slowly closed the Tethyan Sea 

along the northern and northwestern plate boundaries. The 

Sulaiman-Kirthar fold belt (Province 8025, fi g. 1) began 

8003

8042

8025

8024

8001

8023

8022

8021

8026 8002

8028

8043

8063

8062

8061

8004

8044

8045

8033

8030

8031 8032

8046

8047

8034 8035

8006

8048

8005

Indus

Basin

KohatPotwar

8001 Southeast Afghanistan

8002 Himalayan

8003 Indian Shield

8004 Sri Lanka

8005 Indo-Burman

8006 Tenasserim-Shan

8021 Makran

8022 Baluchistan

8023 Central Afghanistan

8024 Afghan

8025 Sulaiman-Kirthar

8026 Kohat-Potwar 

8028 Himalayan Foreland

8030 Chindwara

8031 Satpura-Brahmani

8032 Damodar

8033 Pranhita-Godavari

8034 Assam

8035 North Burma

8042 Indus

8043 Bombay

8044 Cauvery

8045 Krishna-Godavari

8046 Mahanadi

8047 Ganges-Brahmaputra Delta

8048 Irrawaddy-Andaman

8061 Maldives

8062 Lakshadweep

8063 Konkan

60°

60°

70°

70°

80°

80°

90°

10° 10°

0° 0°

20° 20°

30° 30°

40° 40°

90°

100°

100°

Figure 1. Location of the Kohat-Potwar geologic province is shown in green (8026), other assessed provinces within Region 8 are shown in 

yellow. Region 8 geologic provinces as defi ned for the U.S. Geological Survey World Energy Project are numbered, and those not assessed are 

shown in brown; adjacent regions are shown in gray.

2 Petroleum Systems and Related Geologic Studies in Region 8, South Asia
to develop as a result of this oblique collision and rotation. 

Regional uplift and the resulting mountain ranges rising 

on the Eurasian plates to the north and west created a new 

sediment source, and the prevailing south to north sediment 

transport direction on the Indian plate was reversed. From 

Eocene through middle Miocene, a carbonate platform buildup 

occurred intermittently on the shelves around much of the 

Indian plate. A trench formed along the subduction zone as the 

Indian plate began to slip beneath the Eurasian plate (fi g. 11). 

The Eurasian plate shed large volumes of sediments into the 

trench as subduction continued. This terrestrial sediment infl ux 

from the rapidly rising Himalayan, Sulaiman-Kirthar, SinoBurman, and Indo-Burman Ranges signifi cantly exceeded 

carbonate buildup rates on late Miocene platforms (Roychoudhury and Deshpande, 1982) and smothered carbonate reef 

formation along the shelf areas. The former shelf areas along 

the collision zones were either subducted or became emergent 

fl uvial-deltaic environments. In the Kohat-Potwar geologic 

province shallow northeast-trending anticlines and overturned 

folds developed above multiple detachment surfaces (fi g. 12). 

Detachment surfaces as deep as the Eocambrian (late Precambrian) salts developed as a result of continued plate convergence, and associated crustal shortening of as much as 55 km 

occurred (Jaswal and others 1997; Kemal and others, 1992). 

The proto-Indus, Narmada, Ganges, Brahmaputra, 

Megna, Chindwin, and Irrawaddy Rivers developed extensive 

deltas as the Himalayas and other ranges continued to shed 

sediments at a high rate. Today, uplift of the Himalayas and 

subduction of the Indian plate continues, and the growth rate 

of the Indus, Ganges-Brahmaputra (Megna), and Irrawaddy 

deltas remains high. In the Kohat-Potwar area, crustal shortening also continues. 

200 m

pC Mzim Mzim Pz Pz

pC

Pz

Pz

MzPz

Pg TrPr

N

Pg

pC

Pg

N

N

Pg

N

Ts N

Pg

Pg

TKim Pg

Pg

N

Q

Pg

pC

pC

TKv

Pg

TKv

Q

pC

Mzim

Pzi

Mzim

Pz

Pz

Ts TKim

Mzim

Mzim TrPr TrPr

pC

Ti pC

Pz

pC

TKim

TKim

TKim

Ti

Legend

Pzi - Paleozoic igneous rocks

0 190 380 570 95

Kilometers

PzpC - Paleozoic and Precambrian undivided

pC - Undivided Precambrian rocks

Surface water

Unmapped area

MzPz - Mesozoic and Paleozoic undivided

Pz - Paleozoic rocks

N - Neogene sedimentary rocks

Pg - Paleogene sedimentary rocks

Ts - Undifferentiated Tertiary sedimentary rocks

Mz - Mesozoic undivided

TKim - Tertiary and Cretaceous igneous and metamorphic rocks

TKv - Tertiary and Cretaceous volcanic rocks

Mzim - Mesozoic intrusive and metamorphic rocks

Fault

River

Water depth contour

Scale

Indus River

Lower

Indus

Basin

Karachi

Rann of

Kutch

Delhi

Islamabad

Upper Indus

Basin

Middle Indus

Basin

Jacobabad or MariKandhot High

Sargodha High

A R A B I A N

S E A

 8021

Makran

 8024

Afgan

 8026

Kohat-Potwar

 8002

Himalyan

A F G HA N I S T A N

P A K I S T A N

I N D I A

 8025 Sulaiman-Kirthar

Oil and /or gas field

Country Boundaries

Geologic Province boundary

TrPr - Triassic through Permian undivided

Sui

Khaur

Figure 2. Generalized geology of the Kohat-Potwar geologic province and surrounding area (modifi ed from OGDC, 1997; Wandrey and Law, 

1999; Wandrey and others, 2000).

Patala-Nammal Composite Total Petroleum System, Kohat-Potwar Geologic Province, Pakistan 3
Surgar Range

Foreland

Peshawar Basin

Salt Range Thrust Fault

Jehlum Fault

0 50 km

Scale

Main Boundary Thrust

River

Fault

Anticline

Kalabagh 

Fault

Islamabad

Soan RiverSoan River

Indus 

River Indus River

Kohat

Potwar Plateau

Kohat Plateau

Parachinar-Muree Fault

Bannu

Depression Kurram Fault

Salt Range

Figure 3. Generalized structure of Kohat-Potwar geologic province area (modifi ed from Kazmi and Rana 1982; Khan and others 1986; Law and 

others 1998).

•

• • • • • • • • • • •• • • • • •

• • •

•

• •

Pakistan

India

8002

8042

8025

Lahore

Amritsar

0 100 200 KILOMETERS

Islamabad

Country boundary

Oil fields

Gas fields

Patala-Nammal Total Petroleum System 802601 and 

Kohat-Potwar Intrathrust Basin (80260101)

Other geologic province boundary

Kohat-Potwar geologic province 8026

Sembar-Goru/Ghazij Total Petroleum System 804201

•

•

Figure 4. Extent of total petroleum systems in the KohatPotwar geologic province area.

4 Petroleum Systems and Related Geologic Studies in Region 8, South Asia
X

Shale

Limestone

Sandstone

Siltstone, shale, 

and sandstone

Shale, siltstone, 

and sandstone

Gas production

or show

Oil production,

show, or seep

Source rock

potential

Flysch

EXPLANATION

Volcanics

Conglomerate

No deposition 

or rocks eroded

PRECAMBRIAN CAMBRIAN ORDOVICIAN- CARBONIFEROUS PERMIAN TRIASSIC JURASSIC CRETACEOUS PALEOGENE NEOGENE

PLEISTOCENE

PLIOCENE

MIOCENE

OLIGOCENE

EOCENE

PALEOCENE

Kohat North Potwar Salt Range

Nagri

Khel

Salt

Mianwali

Khisor

Jutana

Khewra

Kussak

Shinawuri/Springwar

Baghanwala

Dandot

Warchha

Sardhai

Amb

Chhidru

Tredian

Kingriali

Datta

Samana Suk

Chichali

Hangu

Lockhart

Patala

Nammal

Sakesar

Kuldana

Jatta

Gypsum

Panoba

Kohat

Kirthar

Kamlial Murree

Chinji

Dhok Pathan

Soan

Siwalik Rawalpindi Zaluch

Epoch Group

Gypsum and

anhydrite

Nilawahan

X

X

X

X

X

Torba

X

X

Jhelum Baroch

Margala

Hill

Kamlial

Chinji

Nagri

Dhok Pathan

Upper

Siwalik

Salt Range

Wargal

Lumshiwal

Mogul Kot/Kawagarh

Surgar Chharat Makarwal

Sakesar

Chorgali

Sulaiman

Goru

Sembar

Pab

QUAT.

Musa Khel

Figure 5. Generalized stratigraphy of the Kohat-Potwar area (modifi ed from OGDC, 1996; Quadri, 1996; Kemal, 1992; Iqbal and Shah, 

1980; Shah and others, 1977).

Patala-Nammal Composite Total Petroleum System, Kohat-Potwar Geologic Province, Pakistan 5
Indian 

Plate

Australian

Plate

African

Plate

Antarctic

Plate

Burma

Plate

Eurasian Plates

Indian 

Plate

Lowlands

Mountains

Shelf

Marine

Australian

Plate

African

Plate

Antarctic

Plate

Eurasian Plates

Burma

Plate

Figure 6. Paleogeographic map of the Middle Jurassic (approximately 166 Ma). Perspective is from lat 20°S., long 68°E. (modifi ed 

from Scotese and others, 1988; Scotese, 1997).

Figure 7. Paleogeographic map of the Early Cretaceous (approximately 130 Ma). Perspective is from lat 20°S., long 68°E. (modifi ed 

from Scotese and others, 1988; Scotese, 1997).

Indian 

Plate

Australian

Plate

African

Plate

Antarctic

Plate

Eurasian 

Plates

Burma Plate

Mascarne

Basin

Lowlands

Mountains

Shelf

Marine

African

Plate

Antarctic

Plate

Indian 

Plate

Australian

Plate

Burma Plate

Seychelles

Mascarene 

rift basin

Ninety East Ridge

Kerguelen

Hot Spot

Kerguelen

Hot Spot

Eurasian 

Plates

Tethyan Sea

Madgasgar

Figure 8. Paleogeographic map of the Late Cretaceous (approximately 94 Ma). Perspective is from lat 20°S., long 68°E. (modifi ed from 

Scotese and others, 1988; Scotese, 1997).

Figure 9. Paleogeographic map of the latest Cretaceous (approximately 69 Ma). Perspective is from lat 20°S., long 68°E. (modifi ed from 

Scotese and others, 1988; Scotese, 1997).

6 Petroleum Systems and Related Geologic Studies in Region 8, South Asia
Indian 

Plate

Lowlands

Mountains

Shelf

Marine

Australian

Plate

African

Plate

Antarctic

Plate

Eurasian

Plates

Ninety East Ridge

Myanmar

Madagascar

Seychelles

Somali

Basin

Mascerne

Basin

Antarctic

Plate

African

Plate

Australian

Plate

Indian 

Plate

Eurasian 

Plates

Madagascar Nintey East Ridge

Burma 

Plate

Seychelles

Somali

Basin

Mascerne

Basin

Bengal 

Basin

AssamArakan

Shelf Bombay

Shelf

Indus

Shelf

Figure 10. Paleogeographic map of the middle Eocene (approximately 50 Ma). Perspective is from lat 20°S., long 68°E. (modifi ed from 

Scotese and others, 1988; Scotese, 1997).

Figure 11. Paleogeographic map of the late Oligocene Epoch 

(approximately 27 Ma). Perspective is from lat 20°S., long 68°E. (modifi ed from Scotese and others, 1988; Scotese, 1997). 

Kalachitta Range Salt Range Punjab Platform

Neogene

Paleogene

Cenozoic

undivided

Permian

EXPLANATION

Cambrian

Eocambrian

Precambrian

Fault

0

0

15 30 MILES

25 50 KILOMETERS

SOAN SYNCLINE

Kot Sarang

Dhulian Karsal

Balkassar 

Kallar Kahar Lilla-1

Sea Level

4 km

8 km

N S

Balkassar Field location

with subsurface

well data

Figure 12. Generalized cross section showing structure through the Potwar Plateau (modifi ed from Malik and others, 1988). See fi gure 13 for 

location of fi elds used on cross section.

Patala-Nammal Composite Total Petroleum System, Kohat-Potwar Geologic Province, Pakistan 7
Stratigraphy

The Kohat-Potwar geologic province depositional record 

is relatively complete from Late Proterozoic to Holocene (fi g. 

5). Late Proterozoic metamorphic basement rocks are overlain by oil-impregnated shales, sandstones, and interbedded 

carbonates and evaporates of the Late Proterozoic and Lower 

Cambrian Salt Range Formation. The upper part of the Salt 

Range consists of thick carbonates overlain by evaporites 

marking the top of the formation. Potential source beds and oil 

shows have been identifi ed within the evaporite sections (Shah 

and others, 1977; Iqbal and Shah, 1980). The thickness of the 

Salt Range Formation varies from 50 to more than 1,000 m, 

due partly to dissolution of these evaporates. Above the Salt 

Range, evaporites are as much as 150 m of marine shales and 

massive sandstones representing braided-stream deposits of 

the Lower Cambrian Jhelum Group, Khewra Formation, which 

has produced oil at the Adhi, Chak Naurang, and Rajian fi elds 

(Khan and others, 1986; Petroconsultants, 1996) (fi g. 13). As 

much as 180 m of the Kussak Formation glauconitic shoreface 

sandstones and siltstones overlie the Khewra. The Kussak 

has produced oil at the Missa Keswal fi eld (Petroconsultants, 

1996). The overlying Jutana Formation consists primarily of 

sandy carbonates and nearshore sandstones. The Upper Cambrian Baghanwala Formation shales and interbedded sandstones in the Potwar Plateau and Salt Range area, and contemporaneous Khisor Formation salts in the Kohat area, mark the 

top of the Cambrian stratigraphic sequence. The top of this 

sequence also marks the beginning of a hiatus that lasted until 

the Permian.

The Permian Nilawahan Group consists of the Tobra 

Formation glacial tillites, siltstones, and shales; the Dandot 

Formation alluvial or glacial coarse-grained sandstones and 

shales; the Warchha Formation coarse-grained argillaceous 

sandstones, and occasional shales; and the Sardhai Formation, 

which is similar to the Warchha except for a greater number 

of fi ne-grained-sandstone intervals (Shah and others, 1977; 

Iqbal and Shah, 1980; Kemal, 1992). Three fi elds in the southeast portion of the Potwar Plateau have produced oil or gas 

from Tobra reservoirs. Overlying the Nilawahan Group is the 

Zaluch Group consisting of Upper Permian Amb Formation 

Soan River Soan River

Indus River Indus River

Peshawar Basin

Kohat

Salt Range Thrust

Surghar Range

Jehlum Fault

Khaur

Balkassar

Chak Naurang

Karsal

Dakhni

Joyamair

Bhal Sayedan

Ratana

Sadkal

Turkwal

0 50 km.

Scale

Main Boundary Thrust

River

Fault

Thrust fault

Anticline

Oil field

Gas field

Oil and gas

field

Insufficient

field data

Kalabagh 

 Fault

Kheri Murat Fault

Adhi

Toot Fim Kassar

Dhulian

Bhangali

Mehal

Dhurnal

Kal

Rajian

Pariwali

Missa

Kessal

Explanation

Figure 13. Generalized oil and (or) gas fi eld and structure map of Kohat-Potwar area (modifi ed from Kemal, 1992; Government of Pakistan, 2001; 

Kazmi and Rama, 1982; Khan and others, 1986; Law and others, 1998; Petroconsultants, 1996).

8 Petroleum Systems and Related Geologic Studies in Region 8, South Asia
shelf carbonates, Wargal Formation shelf-carbonate sequences, 

and the Chhidru Formation marls and coarsening upward 

sandstones. The Wargal has produced oil at the Dhurnal fi eld. 

Although Mesozoic rocks are generally preserved in 

the Salt Range and southeast Potwar Basin, part or all of the 

section is missing from the Kohat Plateau and northwestern 

Potwar deformed zone (Jaswal and others, 1997). Depositional 

thinning toward the west combined with erosion accounts for 

the missing rocks. Deposited on the unconformable Permian strata are continental, coarse- to fi ne-grained sandstones, 

shales, and carbonates of the Triassic Musa Kehl Group 

Mianwali and Tredian Formations. Overlying the Tredian 

are shelf carbonates of the Triassic Kingriali Formation. The 

Triassic Formations were formerly referred to collectively as 

the Wulgai Formation (Shah and others, 1977). The Jurassic 

strata include the Shirinab or Datta and Shinawari Formations 

consisting of nearshore variegated siliciclastics that contain 

some nonmarine-sandstone intervals (Khan and others, 1986). 

The Datta has produced oil and gas from three fi elds, including Dhulian, in the northwest Potwar Plateau area. Overlying 

these nearshore formations are as much as 900 m of Samana 

Suk Formation platform carbonates. The Lower Cretaceous 

section consists of Chichali Formation basinal shales, Sembar 

and Lower Goru Formations coarsening-upward shoreline 

packages (late highstand), and Lumshiwal Formation sandstones (maximum basin fl ooding surface). The Upper Goru, 

Kawagarh, or upper Moghul Kot siliciclastics representing 

Late Cretaceous lowstand events are present southeast of 

the Salt Range and on the Kohat Plateau but are not reported 

within the Potwar Basin. 

Cenozoic deposition began with the Paleocene-Eocene 

Makarwal Group. Hangu Formation siliciclastics were 

deposited fi rst on an erosional surface marking the top of 

the Cretaceous Lumshiwal Formation. There is a transitional 

contact between the Hangu and Pab and the overlying Lockhart Formation carbonate-shelf system. The contact between 

the Lockhart and the shallow-marine shales and subordinate 

carbonates of the Patala Formation is also transitional (Shah 

and others, 1977; Iqbal and Shah, 1980; Kemal, 1992). Oil 

production has been attributed to the Lockhart and Patala. The 

overlying Eocene Nammal and Panoba Formations are shallow-marine to lagoonal shales and interbedded limestones 

with a transitional contact between the Patala and the Nammal. 

Overlying the Nammal and Panoba are the lower Eocene 

Sakesar or Margala Hill Formation marine limestones and 

shales. Oil or gas production from eight fi elds spanning the 

Potwar Plateau are attributed to the Margala Hill. Even though 

Iqbal and Shah (1980) indicated that the probably contemporaneous lower Eocene Bahadur Khel Salt is present only in the 

Kohat Plateau area (fi g. 5), oil or gas production at three fi elds 

on the Potwar Plateau has been attributed (Petroconsultants, 

1996) to the Bahadur Khel Salt Formation (Shah and others, 

1977; Petroconsultants, 1996). The Chharat Group includes 

marine shales and interbedded limestones of the lower Eocene 

Chorgali Formation, the shales of the upper Eocene Kohat 

Formation, and the highstand shales and ramp carbonates of 

the Oligocene Kirthar Formation that were deposited at least 

in the Kohat and northern Potwar area. Oligocene rocks are 

missing from most of the basin. An erosional surface marks a 

change to alluvial environments represented by the Miocene to 

Pliocene Murree Formation fl uvial sandstones and siltstones 

and the Kamlial Formation fl uvial sandstones and clays of the 

Rawalpindi Group. The Murree Formation contains the youngest reported oil-producing reservoirs in the Kohat-Potwar geologic province. Pliocene and Pleistocene Siwalik Group fl uvial 

sandstones and conglomerates mark the top of the stratigraphic 

column in the area. 

Production History

In 1866, the fi rst oil well on the western Indian subcontinent was drilled at Kundal (fi g. 13). The fi rst commercial oil 

discovery occurred in 1914 when the Attock Oil Company 

completed a 214-ft well on a thrust-faulted anticline near the 

town of Khaur (Khan and others, 1986) (fi g. 13). Since the 

discovery, there have been more than 340 wells drilled in the 

fi eld. Production at Khaur is from Sakesar and Murree Formation reservoirs. Drilling from 1920 to 1935 resulted in success 

at Dhulian, a structural dome 17 km southeast of Khaur. Other 

discoveries followed with Joya Mair in 1944, Balkassar in 

1946, Karsal in 1956, and Tut in 1967 (fi g. 13). The fi rst commercial gas fi eld—Adhi—was found in 1979. The Adhi gas 

fi eld produced from rocks ranging in age from Cambrian to 

Eocene (Petroconsultants, 1996). Eighteen oil and three gas 

fi elds were discovered in the Kohat-Potwar geologic province between 1915 and 1996, and several prospects that were 

unsuccessfully tested in the 1950s and 1960s are now being 

reexamined with good results (Quadri and Quadri, 1998). 

Production in the Kohat-Potwar geologic province comes 

primarily from faulted anticlinal traps in rocks ranging in age 

from Cambrian to Miocene, and at depths of less than 20 m 

to greater than 1,030 m. The largest oil and gas fi eld found to 

date is the Dhurnal fi eld with areal closure of 13.5 km2 and 

vertical closure of 500 m. The initial in-place oil estimate for 

Dhurnal was 102 MMBO (million barrels of oil) (Jaswal and 

others, 1997) 

The plot of cumulative new-fi eld wildcat wells versus 

completion year for the Kohat-Potwar geologic province (fi g. 

14) shows that the rate of fi eld discovery through time has 

increased. The known oil fi elds ranked by size and grouped 

in discovery thirds does not show a signifi cant decrease in 

fi eld size in progressive thirds (fi g. 15). The small decrease 

in fi eld size through time indicates that the province is still 

not mature in terms of exploration. A mature province would 

show a larger decrease in fi eld sizes between the fi rst and third 

thirds. The small range of fi eld sizes shown in fi gure 15 may 

also be the result of relatively consistent thrust mechanisms 

creating many anticlinal traps of similar volume and orientation. The size of oil fi elds discovered during the second and 

third third of the exploration history further indicates that, 

Patala-Nammal Composite Total Petroleum System, Kohat-Potwar Geologic Province, Pakistan 9
even though the prospective area is small and appears well 

explored, potential remains for the discovery of additional 

medium and small fi elds. The plot showing cumulative oil 

volumes found versus the cumulative number of new-fi eld 

wildcats (fi g. 16) shows a consistent level of effort required to 

fi nd similar volumes of oil. In a more mature area, the number 

of wildcat wells required to fi nd the same volume of oil would 

be expected to increase and the curves on the plots to fl atten. 

The number of gas-fi eld discoveries was insuffi cient to create 

a meaningful plot. The size of the oil fi elds discovered through 

time has remained consistent (fi g. 17), but there has been a signifi cant increase in the discovery rate for smaller fi elds. Exploration for deeper targets has increased, but shallow fi elds are 

still being found (fi g. 18). The largest fi eld may have already 

been found, but potential for additional oil and gas discoveries 

in complex structural traps remains good. 

Composite Petroleum System

Source Rock

The U.S. Geological Survey (USGS) recognizes that 

there are several individual total petroleum systems in this 

area. For assessment purposes, however, they were combined into a single composite Eocambrian-Miocene TPS (the 

Patala-Nammal TPS, 802601) because few correlations of 

source to reservoir hydrocarbons were available at the time 

of the assessment. In addition, multiple stacked sources and 

reservoirs—and extensive fault systems—allow the mixing of 

0

10

20

30

40

50

60

70

80

90

1860 1880 1900 1920 1940 1960 1980 2000

DRILLING-COMPLETION YEAR

CUM. NEW-FIELD WILDCAT WELLS (No.)

Figure 14. Plot showing the cumulative number of new-fi eld wildcat wells versus well-completion 

year. This plot is an indicator of exploration effort. Based on Petroconsultants well and fi eld data 

(Petroconsultants, 1996).

hydrocarbons from multiple sources making further subdivision more diffi cult. The Paleocene Patala Formation appears 

to be the primary source of hydrocarbons, but other potential 

source rocks may be contributing in different parts of the 

basin.

There are several potential source rocks in the 

Kohat-Potwar geologic province. These include the Late 

Proterozoic–Lower Cambrian Salt Range; Permian Wargal, 

Sardhai, and Chhidru; Paleocene Lockhart; and Eocene 

Patala Formations (OGDC, 1996; Quadri and Quadri, 1996). 

Most of the available information and analyses available 

was derived from samples collected on the Potwar Plateau 

and easternmost Kohat Plateau. The remainder of the 

Kohat Plateau source-rock potential is not as well known. 

Correlated columnar sections (Shah and others, 1977) show 

a generalized thinning of the Paleocene-Eocene stratigraphic 

sequences toward the southwest part of the Kohat Plateau. 

Lower Cretaceous Sembar and Lower Goru temporal 

equivalents—the Chichali and Lumshiwal Formations—

may be the youngest mature rocks with source potential 

throughout most of the Kohat Plateau.

The oldest potential source rocks are in the Salt Range 

Formation, which consists of a clastic-dominated lower section, carbonate-dominated middle section, and an evaporitedominated upper section. Potential source-rock intervals are 

found primarily in the upper evaporite sequence. The Permian 

Sardhai and Chhidru, although sandy, have suffi ciently high 

total organic carbon (TOC) values to have source-rock potential 

(Quadri and Quadri, 1997). The shallow-marine shales of the 

Eocene Patala Formation, ranging in thickness from 20 to 180 

m, are the probable predominant oil source in the Potwar Basin 

(OGDC, 1996, oral commun.). Patala TOC ranges from 0.5 per10 Petroleum Systems and Related Geologic Studies in Region 8, South Asia
cent to more than 3.5 percent, with an average of 1.4 percent, 

and are type-II and -III kerogens. The exception to this may be 

the Dhurnal fi eld (fi g. 14), where Patala samples have low TOC 

values, whereas TOC values in the Permian Wargal are 1.0 percent and in the Lockhart they are 1.4 percent (Jaswal and others, 

1997). Oil samples from Dhurnal fi eld also do not match those 

known to be sourced by the Patala. Sulfur content of the oils is 

less than 0.65 percent, except at Joyamair where sulfur content 

is greater than 2 percent (Khan and others, 1986).

Maturation

Thermal maturities for Kohat-Potwar rocks range, from 

Ro 0.3 to more than 1.6 percent. A basin profi le (OGDC, 

1996) indicates vitrinite refl ectance equivalent maturities 

of 0.62 to 1.0 percent for Tertiary rocks in the productive 

part of the Potwar Basin (fi g. 19). Fluid-inclusion data, with 

vitrinite-refl ectance data used for calibration, shows calculated 

and measured Ro samples between 0.6 and 1.1 percent for 

1

10

100

1,000

0123456

OIL-FIELD RANK BY SIZE

KNOWN OIL-FIELD SIZE (MMB

O

First third of fields discovered

Second third of fields discovered

Third third of fields discovered

1

10

100

1,000

0123456

OIL-FIELD RANK BY SIZE

GROWN OIL-FIELD SIZE (MMBO)

Figure 15. Maturity of exploration indicator plots showing known and grown (expected fi nal size 

when production is ended) fi eld sizes grouped in thirds by age of discovery and ranked by size. Based 

on Petroconsultants fi eld data (Petroconsultants, 1996).

Patala-Nammal Composite Total Petroleum System, Kohat-Potwar Geologic Province, Pakistan 11

(MMBO)
Cretaceous, 0.5 to 0.9 percent for Jurassic, and 0.65 to 0.95 

percent for Permian rocks (Tobin and Claxton, 2000). North 

of the main boundary thrust fault, maturities are higher. In the 

northern and probably central basin, Cretaceous rocks are in 

the 1.0 to 1.6 percent Ro range. Dry gas generation begins near 

1.3 percent Ro. 

Generation and Migration

Generation of hydrocarbons most likely began in Late 

Cretaceous time for Cambrian through Lower Cretaceous 

source rocks and again from Pliocene time to the present for 

younger source rocks (OGDC, 1996). Burial-history plots by 

Law and others (1998) (fi g. 20) start at about 30 Ma and therefore show only a late or second period of generation beginning 

20 to 15 Ma and continuing to the present. Two distinct overpressuring regimes were reported by Law and others (1998). 

A Neogene overpressuring regime was attributed to tectonic 

compression and undercompaction, and a pre-Neogene overpressuring regime is attributed to combined hydrocarbon generation and tectonic compression The burial-history plots of 

Law and others (1998) also indicate that maximum burial was 

reached approximately 2 million years ago. Even though there 

were probably two distinct periods of generation from two 

different groups of source rocks, suffi cient source-to-reservoir 

correlation data were not available to clearly defi ne separate petroleum systems. In many oil and gas fi elds, there are 

stacked source and reservoir rocks possibly resulting in mixing 

of oils. Migration is primarily over short distances updip and 

0

100

200

300

400

500

600

700

0 10 20 30 40 50 60 70 80 9

CUM. NEW-FIELD WILDCAT WELLS (No.)

CUM. KNOWN OIL VOLUME (MMBO)

0

0

100

200

300

400

500

600

700

0 10 20 30 40 50 60 70 80 9

CUM. NEW-FIELD WILDCAT WELLS (No.)

CUM. GROWN OIL VOLUME (MMBO)

0

Figure 16. Plots showing cumulative known and grown oil volumes versus the cumulative number 

of new-fi eld wildcat wells. The trends exhibited indicate continued success in fi nding relatively 

consistent volumes of oil with a similar amount of exploration effort. Based on Petroconsultants 

fi eld data (Petroconsultants, 1996).

12 Petroleum Systems and Related Geologic Studies in Region 8, South Asia (MMBO)
Figure 17. Plot showing fi eld size versus fi eld-discovery year serves as an indicator of exploration 

maturity. Based on Petroconsultants fi led data (Petroconsultants, 1996).

Figure 18. Plot showing reservoir depth versus oil-fi eld-discovery year. This plot shows increasing 

depth of discoveries through time. Based on Petroconsultants fi eld data (Petroconsultants, 1996).

Patala-Nammal Composite Total Petroleum System, Kohat-Potwar Geologic Province, Pakistan 13

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

5,000

1860 1880 1900 1920 1940 1960 1980 2000

FIELD-DISCOVERY YEAR

RESERVOIR DEPTH, OIL FIELDS ((m) m

1

10

100

1,000

1860 1880 1900 1920 1940 1960 1980 2000

FIELD-DISCOVERY YEAR

KNOWN OIL-FIELD SIZE 

(MMBO)

vertically into adjacent reservoirs and through faults and fractures associated with plate collision and thrusting.

Reservoir Rocks 

Reservoir rocks include Miocene alluvial sandstones, 

Paleogene shelf carbonates, Jurassic and Permian continental 

sandstones, and Cambrian alluvial and shoreface sandstones 

(Shah and others, 1977; Iqbal and Shah, 1980). On the Potwar 

Plateau, oil or gas has been produced from the following formations: Cambrian Kherwa, Kussak, and Jutana; Permian Tobra, 

Amb, and Wargal; Jurassic Datta; Cretaceous Lumshiwal; 

Paleocene Khairabad, Lockhart, Patala, and Nammal; Eocene 

Bhadrar, Chorgali, and Margala Hill Limestone; and Miocene 

Murree (Khan and others, 1986; Petroconsultants, 1996) (fi g. 

5). Production from more than one of these reservoirs (in one 

case fi ve reservoirs) was reported at 12 of the 22 fi elds in the 
database (Petroconsultants, 1996). More than 60 percent of the 

producing reservoirs (by fi eld) are of Cenozoic age (fi g. 21), 

with the majority of those being Eocene carbonates. 

Sandstone porosities range from less than 5 percent to 

30 percent and average 12 percent to 16 percent. Permeability 

ranges from less than 1 millidarcy (mD) to greater than 300 

mD, with the average ranging from 4 to 17 mD (Khan and 

others, 1986). At the Dhurnal fi eld and probably elsewhere in 

the basin, hydrocarbons in the carbonate reservoirs are primarily from tectonically induced fracture porosity on strike with 

structural trends (Jaswal and others, 1997). Approximately 60 

percent of the identifi ed producing reservoirs are carbonates 

(fi g. 22).

Because oil and gas production volumes are reported by 

fi eld rather than reservoir in the database used (Petroconsultants, 1996) and 12 of 21 fi elds reported production from more 

than one reservoir, no attempt was made to assign volumes of 

oil and gas to reservoirs, ages, or lithologies. 

Traps and Seals

Most of the fi elds discovered in the Kohat-Potwar geologic province to date are either overturned faulted anticlines, 

popup structures, or fault-block traps. In this area, anticlinal 

features strike generally east-northeast to west-southwest and 

are approximately parallel to the plate-collision zone. Many 

of these folded structures are amplifi ed, or they are only present above a detachment zone in Eocambrian salts. The latest 

trap-forming thrust events began at approximately 5 and 2 Ma 

(Jaswal and others, 1997). Seals include fault truncations and 

interbedded shales and the thick shales and clays of the Miocene and Pliocene Siwalik Group . 

Assessment Unit

The Kohat-Potwar Intrathrust assessment unit (AU) 

(80260101), is also a composite. The rocks of this AU include 

sandstones, shales, and coals of deltaic to fl uvial facies and 

carbonates and shales of shelf environments and range in age 

from Eocambrian to Miocene.

Assessment of Undiscovered 

Oil and Gas

Based on data current to 1996 provided by Petroconsultants International Data Corporation, the Kohat-Potwar 

geologic province was ranked 174th in cumulative production 

and reserves of oil and gas worldwide (Klett and others, 1997). 

The Kohat-Potwar geologic province (8026) did not meet the 

minimum cumulative production cutoff to be included in the 

assessment as a priority province, but due to its long history 

of oil production, remaining potential, and geologic and geographic relationship with the rest of the Greater Indus Basin, 

it was categorized as a boutique province for the USGS World 

Petroleum Assessment 2000 (U.S. Geological Survey World 

Energy Assessment Team, 2000). Known petroleum volumes 

are 0.3 billion barrels of oil (BBO) and 1.9 trillion cubic feet 

of gas (TCFG) for a total of 0.7 billion barrels of oil equivalent 

(BBOE) including natural gas liquids (Petroconsultants, 1996); 

this volume is less than 0.1 percent of world volume (excluding 

the United States). In the Kohat-Potwar geologic province 18 

oil and 3 gas fi elds had been discovered by 1996 (Petroconsultants, 1996). 

0.6 Ro

1.0 Ro

0.6 Ro

0.6 Ro

Approximate 

vitrinite reflectance

Kalachitta Range Salt Range Punjab Platform

Neogene

Paleogene

Cenozoic

undivided

Permian

EXPLANATION

Cambrian

Eocambrian

Precambrian

Fault

0

0

15 30 MILES

25 50 KILOMETERS

SOAN SYNCLINE

Kot Sarang

Dhulian Karsal

Balkassar Oxy

Kallar Kahar Lilla-1

Sea Level

4 km

8 km

N S

Figure 19. Generalized cross section showing structure through the Potwar Plateau (modifi ed from Malik and others, 1988) and generalized 

maturity profi le (modifi ed from OGDC, 1996). 

14 Petroleum Systems and Related Geologic Studies in Region 8, South Asia
0 0

5,000

10,000

15,000

20,000

30 25 20 15 10 5

2,000

4,000

6,000

Depth in Meters

0 

5,000

10,000

15,000

20,000

30 25 20 15 10 

Depth in Feet

300 (F)

250 (F)

150 (F)

Time (Ma)

3

250 (

200 (F)

150 (F)

Paleocenerocks

Cambrian andPrecambrianrocks

100 (F)

0 

Oil Window

100 (F)

OtherPaleozoicrocks 200 (F)

Mesozoicrocks

Mesozoicrocks

Neogenerocks 

Neogenerocks 

Paleocenerocks

Depth in Feet

Time (Ma)

Peshawar Basin

Salt Range Thrust

Jehlum Fault

0 50 km. Scale

Main Boundary Thrust

RiverFaultAnticlineOil fieldGas fieldOil and GasfieldInsufficientfield data

Kalabagh Fault

Islamabad

Index Map

Fim Kassar

Dakhni

Indus River

Figure 20. Generalized burial-history plots for the ODGC Dakhni 1 well (left) and the Gulf Oil Fim Kassar well (right) (modifi ed from Law and others, 1998)
0

2

4

6

8

10

12

14

16

18

20

Miocene Eocene Paleocene Jurassic Permian Cambrian

Age

Number of Fields

Figure 21. Distribution of producing reservoirs by age and number of fi elds in which they occur 

(based on Petroconsultants reservoir and fi eld data; Petroconsultants, 1996).

Figure 22 - Distribution of producing reservoir lithology by age and

number of fields reporting production from that age group and lithology type.

1 5 Based on Petroconsultants field and reservoir data (Petroconsultants, 1996).

1

6

3

6

15 fields

reported

Eocene Limestone

Paleocene Limestone

Permian Limestone

Cambrian Dolomite

Jurassic Sandstone

Permian Sandstone

Cambrian Sandstone

Figure 22. Distribution of producing reservoirs by age, lithology, and number of fi elds reporting production from that age group and lithology type. Based on Petroconsultants fi eld and reservoir data 

(Petroconsultants, 1996).

16 Petroleum Systems and Related Geologic Studies in Region 8, South Asia
Previous estimates of undiscovered oil and gas in this 

region include those by Kingston (1986) and Masters and 

others (1998). Kingston (1986) estimated the mode of undiscovered oil in the Kohat-Potwar province at 0.1 BBO and gas 

at 0.1 TCF. Masters and others (1998) estimated the mean for 

undiscovered oil in this province as 0.12 BBO and the mean 

for undiscovered gas as 3.0 TCF. The methodology utilized in 

those assessments employed analogs from well-known productive regions of the world and also relied heavily on volumetric considerations. 

The 2000 assessment incorporates the petroleum system 

concept as defi ned by Magoon and Dow (1994). The TPS used 

as the geologic basis of the 2000 assessment in the KohatPotwar geologic province is the Patala-Nammal TPS (802601). 

Tables 1, 2, and 3 show the estimated ranges of assessed 

undiscovered oil and gas volumes allocated by assessment unit 

and the totals for the composite Patala-Nammal TPS.

Summary

Source-rock quality in the Kohat-Potwar geologic 

province is fair to good in numerous stratigraphic intervals 

(fi g. 23). Burial depths were in the past, and are today, great 

enough for continued generation from many of these source 

intervals. The Paleocene and Eocene source intervals have 

been in the oil and gas generation window in parts of the 

Kohat-Potwar geologic province for as long as 15 m.y., and, 

in places, generation continues today. Reservoirs are of fair to 

very good quality and exist in close proximity to source rocks. 

The presence of stacked reservoirs greatly improves opportunities for discoveries. Trap development, although widespread, 

was relatively late but coincided with maximum burial and 

probably maximum hydrocarbon generation. Continued crustal 

shortening and uplift in some cases enhanced trap quality and 

Code Undiscovered resources

and field MFS Prob. Oil (MMBO)

type (0-1) F95 F50 F5 Mean F95 F50 F5 Mean F95 F50 F5 Mean

Grand Total: Assessed portions of Kohat-Potwar Province (8026)

Oil fields 54 140 274 149 110 299 637 327 6 17 40 20

Gas fields 273 881 2,054 987 9 30 75 35

Total 1.00 54 140 274 149 383 1,180 2,691 1,314 15 48 115 54

1.00

Gas (BCFG) NGL (MMBNGL)

Table 1. Estimates of undiscovered oil and gas for the Patal-Nammal composite total petroleum system, Kohat-Potwar geologic province 

(8026), Pakistan.

[MMBO, million barrels of oil. BCFG, billion cubic feet of gas. MMBNGL, million barrels of natural gas liquids. MFS, minimum fi eld size assessed (MMBO or 

BCFG). Prob., probability (including both geologic and accessibility probabilities) of at least one fi eld equal to or greater than the MFS. Results shown are fully 

risked estimates. For gas fi elds, all liquids are included under the NGL (natural gas liquids) category. F95 represents a 95-percent chance of at least the amount 

tabulated. Other fractiles are defi ned similarly. Fractiles are additive under the assumption of perfect positive correlation. Shading indicates not applicable]

0

1

2

3

4

5

6

7

1-<2 2-<4 4-<8 8-<16 16-<32 32-<64 64-<128 128-

<256

256-

<512

512-

<1024

1024-

<2048

OIL-FIELD SIZE (MMBO)

NUMBER OF UNDISCOVERED OIL FIELDS

Minimum field size: 1 MMBO

Mean number of

undiscovered fields: 21

Table 2. Expected size distribution for undiscovered oil fi elds in the Kohat-Potwar geologic province.

Patala-Nammal Composite Total Petroleum System, Kohat-Potwar Geologic Province, Pakistan 17
0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

6-<12 12-<24 24-<48 48-<96 96-<192 192-<384 384-<768 768-

<1536

1536-

<3072

3072-

<6144

GAS-FIELD SIZE (BCFG)

NUMBER OF UNDISCOVERED GAS FIELDS 

 

Minimum field size: 6 BCFG

Mean number of

undiscovered fields: 5

 

Table 3. Expected size distribution for undiscovered gas fi elds in the Kohat-Potwar geologic 

province.

GENERATIONMIGRATIONRock Unit

Reservoir Rock

Seal Rock

Overburden Rock

Trap Formation

Preservation

GEOLOGIC

TIME SCALE

PETROLEUM

SYSTEM EVENTS

500 100

MESOZOIC CENOZOIC Unconformity

Source Rock

ACCUMULATION

400 300 200

Salt Range Fm.

Kirthar Fm.

Patala Fm.

Kohat Fm.

Margala Hill/Sakesar

Siwaliks Gp

Baghanwala

Unconformity

PALEOZOIC

Lumshiwal Fm.

Panoba/Nammal Fms.

Khewra Fm.

Kussak Fm.

Jutana Fm.

Tobra Fm.

Sardhai Fm.

Amb Fm.

Unconformity

Datta Fm.

Lockhart Fm.

Hangu Fm.

Chichali Fm.

50 25 Chorgali Fm.

Wargal Fm.

Chhidru Fm.

Murree Fm.

GpJhelum

GpNilawahan

GpZaluch

GpBarochGpSurghar

GpMakarwal

GpChharatGpRawalpindi

Ma

Figure 23. Petroleum system events chart for the Kohat-Potwar geologic province. Colored bars that fi ll less than the full height of the event 

box indicate the event only occurred in parts of the basin.

18 Petroleum Systems and Related Geologic Studies in Region 8, South Asia
in others diminished or destroyed it. Complex structures and 

overpressuring, although creating exploration and drilling 

challenges, also offer additional opportunities. Further opportunities also exist in the Kohat Plateau area where few wells 

have been drilled, but source-rock quality or thickness may be 

lower. The northern folded zone also has potential, although 

structural complexity makes exploration diffi cult.

Selected References

Ahmad, S., Alam, Z., and Khan, A.R., 1996, Petroleum exploration and 

production activities in Pakistan: Pakistan Petroleum Information 

Service, 72 p.

Biswas, S.K., and Deshpande, S.V., 1983, Geology and hydrocarbon 

prospects of Kutch, Saurashtra, and Narmada Basins: Petroleum 

Asia Journal, v. 6, no. 4, p. 111–126.

Drewes, H.,1995, Tectonics of the Potwar Plateau region and the 

development of syntaxes, Punjab, Pakistan: U.S. Geological Survey 

Bulletin 2126, 25 p.

Environmental Systems Research Institute Inc., 1992, ArcWorld 1:3M 

digital database: Environmental Systems Research Institute, Inc. 

[ESRI], scale: 1:3,000,000, [available from ESRI, Redlands, Calif.].

Government of Pakistan, 2001, Privatisation Commission Finance 

Division: Government of Pakistan Web page, [URL <www.gopsale.com/index.htm?press_release.htm&2>].

Iqbal, M.W.A., and Shah, S.M.I., 1980, A guide to the stratigraphy of 

Pakistan: Quetta, Geological Survey of Pakistan Records, v. 53, 

p. 34.

IHS Energy Group[ formerly Petroconsultants], 2001, Probe 4.0 

petroleum exploration and production database:Englewood, Colo., 

IHS Energy Group [database available from IHS Energy Group, 15 

Inverness Way East, D205, Englewood, CO 80112, U.S.A.—includes 

data current as of September 2001].

Jaswal, T.M., Lillie, R.J., and Lawrence, R.D., 1997, Structure and 

evolution of the northern Potwar deformed zone, Pakistan: 

American Association of Petroleum Geologists Bulletin, v. 81, no. 2, 

p. 308–328.

Johnson, E.A., Warwick, P.D., Roberts, S.B., and Khan, I.H., 1999, 

Lithofacies, depositional environments, and regional stratigraphy 

of the lower Eocene Ghazij Formation, Balochistan, Pakistan: U.S. 

Geological Survey Professional Paper 1599, 76 p.

Kazmi, A.H., and Rana, R.A., 1982, Tectonic map of Pakistan: 

Geological Survey of Pakistan, scale: 1:2,000,000.

Kemal, A., 1992, Geology and new trends for hydrocarbon exploration 

in Pakistan, in Ahmed, G., Kemal, A., Zaman, A.S.H., and Humayon, 

M., eds., New directions and strategies for accelerating petroleum 

exploration and production in Pakistan: Proceedings, international 

petroleum seminar, November, 22–24, 1991: Islamabad, Pakistan, 

Ministry of Petroleum and Natural Resources, p. 16–57.

Kemal, A., Balkwill, H.R., and Stoakes, F.A., 1992, Indus Basin 

hydrocarbon plays, in Ahmed, G., Kemal, A., Zaman, A.S.H., and 

Humayon, M., eds., New directions and strategies for accelerating 

petroleum exploration and production in Pakistan: Proceedings, 

international petroleum seminar, November, 22–24, 1991: 

Islamabad, Pakistan, Ministry of Petroleum and Natural Resources, 

p. 76–105.

Khan, M.A., Ahmed, R., Raza, H.A., and Kemal, A., 1986, Geology 

of petroleum in Kohat-Potwar Depression, Pakistan: American 

Association of Petroleum Geologists Bulletin, v. 70, no. 4, p. 396–

414.

Kingston, J., 1986, Undiscovered petroleum resources of South Asia: 

U.S. Geological Survey Open-File Report 86-80, 131 p.

Klett, T.R., Ahlbrandt, T.A., Schmoker, J.W., and Dolton, G.L., 1997, 

Ranking of the world’s oil and gas provinces by known petroleum 

volumes: U.S. Geological Survey Open-File Report 97-463, one 

CD-ROM.

Law, B.E., Shah, S.H.A., and Malik, M.A., 1998, Abnormally high 

formation pressures, Potwar Plateau, Pakistan, in Law, B.E., 

Ulmishek, G.F., and Slavin, V.I., eds., Abnormal pressures in 

hydrocarbon environments: American Association of Petroleum 

Geologists Memoir 70, p. 247–258.

Magoon, L.B., and Dow, W.G., 1994, The TPS—From source to trap: 

American Association of Petroleum Geologists Memoir 60, 60 p.

Masters, C.D., Root, D.H., and Turner, R.M., 1998, World conventional 

crude oil and natural gas identifi ed reserves, undiscovered 

resources, and futures: U.S. Geological Survey Open-File Report 

98-468, 105 p.

Peeock, E.S., Lillie, R.J., Zaman, A.S.H., and Yousaf, M., 1989, 

Structural interpretation of seismic refl ection data from eastern 

Salt Range and Potwar Plateau, Pakistan: American Association of 

Petroleum Geologists Bulletin, v. 73, p. 841–857.

Oil and Gas Development Corporation [OGDC], 1995, Pakistan 

petroleum prospects—An overview: Islamabad, Oil & Gas 

Development Corporation, 22 p.

Oil and Gas Development Corporation [OGDC], 1996, Pakistan 

petroleum prospects—An overview: Islamabad, Oil & Gas 

Development Corporation, 22 p.

Petroconsultants, 1996, Petroleum exploration and production digital 

database: Petroconsultants, Inc., [P.O. Box 740619, 6600 Sands 

Point Drive, Houston TX 77274-0619, U.S.A. or Petroconsultants, 

Inc., P.O. Box 152, 24 Chemin de la Mairie, 1258 Perly, Geneva, 

Switzerland].

Powell, C. M.A., 1979, A speculative tectonic history of Pakistan and 

surroundings; some constraints from the Indian Ocean, in Farah, 

Abdul, and Dejohn, K.A., eds., Geodynamics of Pakistan: Geological 

Survey of Pakistan, p. 5–24.

Quadri, Viqar-un-Nisa, and Quadri, S.M.G.J., 1996, Exploration 

anatomy of success in oil and gas exploration in Pakistan, 1915–94, 

Oil and Gas Journal, v. 94, issue 20.

Quadri, V.N., and Quadri, S.M.J.G., 1998, Failure-to-success targets 

may lie in Pakistan basins: Oil and Gas Journal archives, v. 96, 

issue 1, [accessed 3/2/2000 at URL <http//ogj.pennwellnet.com>].

Quadri, V.N., and Quadri, S.M.J.G., 1998, Pakistan has unventured 

regions, untested plays: Oil and Gas Journal archives, v. 96, issue 

12, [accessed 3/2/2000 at URL <http//ogj.pennwellnet.com>].

Patala-Nammal Composite Total Petroleum System, Kohat-Potwar Geologic Province, Pakistan 19
Quresihi, M.J., Tariq, M.A., and Abid, Q.Z. [Raza, S.M., Hussain, A., 

and Khan, S.H., eds.], 1993, Geological map of Pakistan: Geological 

Survey of Pakistan, scale 1:1,000,000.

Scotese, C.R., Gahagan, L.M., and Larson, R.L., 1988, Plate tectonic 

reconstructions of the Cretaceous and Cenozoic ocean basins: 

Tectonophysics, v. 155, p. 27–48. 

Scotese, C.R., 1997, PALEOMAP Software, Paleomap project, 

[available at URL http://scotese.com].

Sercombe, W.J., Stratton, M., Albertin, M., Wilson, W.P., Roth, B.L., 

Van Nieuwenhuise, R., Pivnik, D.A., and Beck, R.A., 1994, Wrench 

faulting in the northern Pakistan foreland region: The Leading Edge, 

November 1994, p. 1107–1110.

Sercombe, W.J., Pivnik, D.A., Wilson, W.P., Albertin, M.L., Beck, R.A., 

and Stratton, M.A., 1998, Wrench faulting in the northern Pakistan 

foreland: American Association of Petroleum Geologists Bulletin, v. 

82, no. 11, p. 2003–2030. 

Shah, S.M.I., Ahmed, R., Cheema, M.R., Fatmi, A.N., Iqbal, M.W.A., 

Raza, H.A., and Raza, S.M., 1977, Stratigraphy of Pakistan: 

Geological Survey of Pakistan, Memoirs, v. 12, 137 p.

Soulsby, A., and Kemal, A., 1988, A review of exploration activity in 

Pakistan: Oil and Gas Journal, November 21, 1988, p. 56–59. 

Soulsby, A., and Kemal, A., 1988, Source rock maturity key to new 

plays: Oil and Gas Journal, November 28, 1988, p. 81–83. 

Raza, H.A., 1992, Petroleum source rocks in Pakistan, in Gulfaraz, A., 

Kemal, A., Zaman, A.S.H, and Humayon, M., eds., New directions 

and strategies for acceleration petroleum exploration in Pakistan: 

Islamabad, Pakistan, Proceedings of an international petroleum 

seminar, Ministry of Petroleum & Natural Resources, Nov. 22–24, 

1991, p. 129–136.

Roychoudhury, S.C., and Deshpande, S.V., 1982, Regional distribution 

of carbonate facies, Bombay offshore region, India: American 

Association of Petroleum Geologists Bulletin, v. 66, no. 10, p. 

1483–1496. 

Tobin, R.C., and Claxton, B.L., 2000, Multidisciplinary thermal 

maturity studies using vitrinite refl ectance and fl uid inclusion 

microthermometry; A new calibration of old techniques: American 

Association of Petroleum Geologists Bulletin, v. 84, no. 10, 

p. 1647–1665.

U.S. Geological Survey World Energy Assessment Team, 2000, 

U.S. Geological Survey World Petroleum Assessment 2000—

Description and results: U.S. Geological Survey Digital Data Series 

DDS-60, version 1.1, 4 CD-ROMs.

Wandrey, C.J., and Law, B.E., 1999, Map showing geology, oil and 

gas fi elds, and geologic provinces of South Asia: U.S. Geological 

Survey Open File Report 97-470C, version 2, 1 CD-ROM.

Wandrey, C.J., Milici, R.C., and Law, B.E., 2000, Region 8, South Asia, 

in U.S. Geological Survey World Petroleum Assessment 2000—

Description and results: U.S. Geological Survey Digital Data Series 

DDS-60, version 1.1, 4 CD-ROMs.

Waples, D.W., and Hegarty, K., 1999, Seychelles thermal history 

hydrocarbon generation traced: Oil and Gas Journal, v. 97, no. 21, 

p. 78–82.

Warwick, P.D., Javed, S., Mashhadi, S.T.A., Shakoor. T., Khan, A.M., 

and Khan, A.L., 1993, Lithofacies and palynostratigraphy of some 

Cretaceous and Paleocene rocks, Surghar and Salt Range coal 

fi elds, northern Pakistan: U.S. Geological Survey Bulletin 2096, 35 p.

Warwick, P.D., and Shakoor. T., 1993, Lithofacies and depositional 

environments of the coal-bearing Paleocene Patala Formation, Salt 

Range coal fi eld, northern Pakistan: Geological Survey of Pakistan, 

Project Report (IR)PK-109.5, 52 p.

Zaigham N.A., and Mallick, K.A., 2000, Prospect of hydrocarbon 

associated with fossil-rift structures of the southern Indus Basin, 

Pakistan: American Association of Petroleum Geologists Bulletin, v. 

84, no. 11, p. 1833–1848.

Manuscript approved for publication January 9, 2004

Published in the Central Region, Denver, Colorado

Editing, page layout, photocomposition, Richard W. Scott, Jr.

Section 508 compliance, David G. Walters

Webmaster. Tracy A. Pinto

Graphics by the authors

20 Petroleum Systems and Related Geologic Studies in Region 8, South Asia