2D SEISMIC DATA INTERPRETATION AND STRUCTURAL ANALYSIS OF BALKASSAR AREA, CENTRAL POTWAR, UPPER INDUS BASIN, PAKISTAN

A thesis submitted to Bahria University, Islamabad in partial fulfillment of the requirement for the degree of B.S in Geophysics

IRFAN BASHIR AAMIR ZEESHAN AAMIR ZOHAIB HASSAN

Department of Earth and Environmental Sciences Bahria University, Islamabad

2013

ABSTRACT

This dissertation contains the study and interpretation of 2D seismic reflection data of selected seismic lines of Balkassar area, Central Potwar, Upper Indus Basin, Pakistan. The main objective of this research was delineations of subsurface structures favorable for hydrocarbon accumulation. This is area is situated in Chakwal District of Punjab Province and is licensed to Oil and Gas Development Corporation Limited (OGDCL). The seismic data for this dissertation was provided by the Land Mark Resources (LMKR) by the permission of Directorate General Of Petroleum Concessions (DGPC). The data comprised of four seismic lines, base map, and well tops of well Balkassar OXY-01. The name of lines obtained are:

PBJ-4(dip line, SE-NW)

PBJ-5(dip line, SE-NW)

PBJ-6(dip line, SE-NW)

PBJ-10(strike line, NE-SW)

Four prominent reflectors (red, brown, yellow, green) were marked on the basis of their reflection character. They represent Chorgali, Sakesar, Lockhart, Tobra Formations respectively. Two-way time (TWT) was read from the seismic section and average velocities were used from the velocity windows (given on the seismic section) to get the velocities for each shotpoint. These values of average velocities were used to create TWT and Depth contour maps. 3D surface maps were also generated, to get a better image by using Surfer 8.0.

ACKNOWLEDGMENT

All adoration and veneration to Almighty ALLAH. We thank our ALLAH for HIS endless blessings HE bestowed upon us. We thank HIM for making us complete this dissertation. It is The Almighty ALLAH’S help that made our frail effort a success.

We also owe our thanks to Dr. M. Zafar, Head of Department, Earth and Environmental Sciences, Bahria University, Islamabad. His guidance paved our pathway to endure this task in partial fulfillment of our degree requirement.

We express our heartfelt and cordial indebtedness to our internal supervisor Mr. Fahad Mahmood and our external supervisor Mr. Sarmad Hassan Sharif.

Their benevolent and benignant help made the completion of this dissertation a reality. They satisfied our agogness with his bent of the subject. Without their assistance this dissertation would never have been the same.

We would like to thank our parents for their help and support. They were continuously backing us up during the completion of this dissertation. They always came up as a hope in our forlorn and restless nights.

TABLE OF CONTENTS

ABSTRACT i

ACKNOWLEDGEMENT ii

TABLE OF CONTENTS iii

LIST OF FIGURES vii

LIST OF TABLES ix

CHAPTER 1

INTRODUCTION 1

1.1 Introduction to the study area 3

1.2 Location of the area 3

1.3 Research Objectives 5

1.4 Base Map of study area 6

CHAPTER 2

GEOLOGY OF THE AREA 11

2.1 Introduction 11

2.2 Regional Geological setting 11

2.3 Tectonic zone 12

2.4 Sedimentary Basin 14

2.5 Indus Basin 15

2.6 Hydrocarbon Production of the Potwar Area 20

2.7 Petroleum Play of Potwar 21

2.8 Structural Style of the study area 24

2.9 Hydrocarbon Entrapment in Potwar 25

2.9.1 Source Rock 27

2.9.2 Reservoir Rock 27 2.9.3 Traps/Seal 38

2.9.4 The Formation, Accumulation and Migration of Oil 28

2.10 Burial History 30

CHAPTER 3

SEISMIC DATA ACQUSITION 31

3.1 Seismic Data Acqusition 31

3.2 Basic principle of seismic data acquisition 31

3.3 Components of seismic acquisition system 34

3.3.1 Input Devices 34

3.3.1.1 Impulsive energy sources 34

3.3.1.2 Non-Impulsive sources 34

3.3.2 Field Layouts 35

3.3.3 Detection of reflected signal 36

3.3.3.1 Geophone 36

3.3.3.2 Hydrophones 36

3.3.4 Recording stage 37

3.3.4.1 Analogue Recording System 37

3.3.4.2 The Digital Recording System 38

3.4 The CDP method 38

CHAPTER 4

SEISMIC DATA PROCESSING 39

4.1 Demultiplexing 40

4.2 Preprocessor 41

4.2.1. Geometry definition 41

4.2.2. Editing 41

4.3 Trance Balancing AGC 42 4.4 CDP Sort 42

4.5 Deconvolution 42

4.6 Velocity Analysis 42

4.7 Residual Statics 43

4.8 NMO Correction 43

4.9 Mute 43

4.10 Datum Correction 44

4.11 Stack Correction 44

4.12 Finite Difference Migration 44

4.13 Band Pass Filter 44

CHAPTER 5

SEISMIC DATA INTERPRETATION 45

5.1 Introduction 45

5 .1.1.Stratigraphic Analysis 46

5.1.2.Structural Analysis 47

5.2 Interpretation of Available Seismic Sections 48

5.2.1 Marking of prominent Reflectors 50

5.2.2 Tracing the marked reflectors 50

5.2.3 Reflector Identification 51

5.2.4 Faults Identification 51

5.2.5 Time contour maps 54

5.2.6 Velocity Contour Maps 59

5.2.7 Depth contour maps 63

5.2.8 3D time and depth surface models 68

CHAPTER 6 RESULTS AND CONCLUSIONS 73 6.1 Results 73 6.2 Conclusions 73

REFRENCES 74

LIST OF FIGURES

1.1. Tectonic map of Pakistan 1 1.2 D&P lease of Balkassar oil Field. 3 1.3. D&P lease of the study area (highlighted), Potwar sub-basin 4 1.4 Structural map of the Study Area 4 1.5 Location of the well under study 5 1.6 Base map of the Study Area 6 2.1 Tectonic Map of Pakistan 13 2.2 Basins of Pakistan 14 2.3. General Stratigraphy of Upper Indus Basin 16 2.4 Tectonic division of Potwar-Sub Basin 18 2.5 Oil and Gas field of Potwar-Sub-Basin 21 2.6 Balkassar Anticline 25 3.1. Seismic data acquisition 32 3.2. Seismic data acquisition, processing, followed by interpretation 33 5.1. Shotpoint basemap of the project area 49 5.2 Interpreted seismic section, PBJ-4 52 5.3 Interpreted seismic section, PBJ-5 52 5.4. Interpreted seismic section, PBJ-6 53 5.5 Interpreted seismic section, PBJ-10 53 5.6. Time contour map of Chorgali Formation 55 5.7 Time contour map of Sakesar Formation 56 5.8 Time contour map of Lockhart Formation 57 5.9 Time contour map of Tobra Formation 58 5.10. Velocity contour map of Chorgali Formation 59 5.11. Velocity contour map of Sakesar Formation 60 5.12. Velocity contour map of Lockhart Formation 61 5.13. Velocity contour map of Tobra Formation 62 5.14. Depth Contour Map of Chorgali Formation 64 5.15. Depth Contour Map of Sakesar Formation 65 5.16. Depth Contour Map of Lockhart Formation 66 5.17. Depth Contour Map of Tobra Formation 67 5.18. 3D time surface model of Chorgali Formation 68 5.19. 3D time surface model of Sakesar Formation 69 5.20. 3D time surface model of Lockhart Formation 70 5.21. 3D time surface model of Tobra Formation 71 5.22. Proposed Well of Balkassar OXY-01 Seismic line PBJ-4 74

LIST OF TABLES

Table 1.1: Table showing orientation of seismic lines of the study area 7

Table 2.1: Table showing stratigraphic column of the study area 23

Table 3.1: Table showing receiver parameters (adopted from seismic section) 37

Table 3.2: Table showing recording parameters (adopted from seismic section)38