Thesis Contents FINAL

2-D SEISMIC DATA INTERPRETATION AND

PETROPHYSICAL ANALYSIS OF BHANGALI

FIELD ON THE BASIS OF SEISMIC LINES

OX-S88-20, OX-S88-23 & OX-S88-36 AND

BHANGALI-01 WELL, EASTERN POTWAR,

PAKISTAN

By

Omer Kamal Shah

Department of Earth and Environmental Sciences,

Bahria University, Islamabad

2011

2-D SEISMIC DATA INTERPRETATION AND

PETROPHYSICAL ANALYSIS OF BHANGALI

FIELD ON THE BASIS OF SEISMIC LINES

OX-S88-20, OX-S88-23 & OX-S88-36 AND

BHANGALI-01 WELL, EASTERN POTWAR,

PAKISTAN

A thesis submitted to Bahria University, Islamabad in

partial fulfillment of the requirements for the degree of

B.Sc. Honours (Geophysics)

By

Omer Kamal Shah

Department of Earth and Environmental Sciences,

Bahria University, Islamabad

2011

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FINAL APPROVAL OF THESIS

This is to certify that we have read the thesis submitted by Mr. Umar

Kamal Shah of B.Sc. Honours (Geophysics) and we find it of sufficient

standard to fulfill the partial requirements for the degree of B.Sc.

Honours (Geophysics) from the Department of Earth and Environmental

Sciences, Bahria University, Islamabad.

Miss. Sarah Akram

(External Supervisor) ________________________________

Mr. Saqib

(Internal Supervisor) ________________________________

Dr. M. Zafar

(HOD,E&ES) ________________________________

External Examiner ________________________________

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IN THE NAME OF ALLAH,

THE MOST BENEFICIENT, THE

MOST MERCIFUL

iv

DEDICATED TO

MY GRAND PARENTS (May their souls rest in

peace)

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TABLE OF CONTENTS

ABSTRACT xi

ACKNOWLEDGEMENT xii

Chapter # 1 INTRODUCTION 01

1.1 Introduction to the Study Area 01

1.2 Physiography 04

1.3 Objectives of Research 05

1.4 Data Obtained for Interpretation 05

Chapter # 2 STRATIGRAPHIC SEQUENCE 07

2.1 Pre-Cambrian Sedimentary Rocks 07

2.2 Paleozoic Sedimentary Rocks 09

2.2.1 Cambrian 09

2.2.1.1 Khewra Sandstone 09

2.2.1.2 Kussak Formation 10

2.2.2 Permian 10

2.2.2.1 Tobra Formation 10

2.2.2.2 Dandot Formation 11

2.2.2.3 Warchha Formation 11

2.2.2.4 Sardhai Formation 11

2.3 Paleogene Sedimentary Rocks 12

2.3.1 Paleocene 12

2.3.1.1 Hangu Formation 12

2.3.1.2 Lockhart Limestone 13

2.3.1.3 Patala Formation 132.3.2 Eocene 13

2.3.2.1 Nammal Formation 14

2.3.2.2 Sakeser Formation 14

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2.3.2.3 Chorgali Formation 14

2.4 Neogene Sedimentary Rocks 15

2.4.1 Miocene 15

2.4.1.1 Murree Formation 15

2.4.1.2 Kamlial Formation 15

2.4.1.3 Chinji Formation 16

2.4.2 Pliocene 16

2.4.2.1 Nagri Formation 16

Chapter # 3 REGIONAL TECTONIC SETTING 17

3.1 Geological Structure of the Salt Range 19

3.2 Tectonic Setting of Eastern Salt Range/

Potwar Plateau 19

3.2.1 Basement Offsets 20

3.2.2 Fault-Propagation Folds 21

Chapter # 4 PETROLEUM GEOLOGY 22

4.1 Indus Basin 22

4.1.1 Eastern Salt Range/Potwar Plateau 22

4.1.1.1 Source Rocks 22

4.1.1.2 Reservoir Rocks 23

4.1.1.3 Traps 23

4.1.1.4 Burial History 23

Chapter # 5 SEISMIC DATA ACQUISITION 24

5.1 Seismic Energy Sources for Reflection Shooting 24

5.1.1 Vibroseis 25

5.2 Seismic Detectors 26

5.2.1 Geophones 26

5.3 Spread Geometry 27

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Chapter # 6 SEISMIC DATA PROCESSING 28

6.1 Processing Sequence 28

Chapter # 7 SEISMIC DATA INTERPRETATION 31

7.1 2-D Seismic Data Interpretation of Line O/881-CW-06 31

7.1.1 Reflection Selection 32

7.1.2 Fault Identification 33

7.1.3 Base Map 37

7.1.4 Time-Contour Map 37

7.1.5 Average Velocity Graph 39

7.1.6 Depth Section 40

Chapter # 8 PETROPHYSICAL EVALUATION 42

7.1 Log Interpretation Flow Chart 43

7.2 Raw Log Curves 43

7.3 Zone of Interest 43

7.4 Lithology 43

7.5 Volume of Shale 44

7.6 Porosity Calculation 46

7.7 Saturation of Water 48

7.8 Bulk Volume of Water (BVW)

51

7.9 Reserves Estimation 52

CONCLUSIONS 53

REFERENCES 54

APPENDICES 60

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LIST OF FIGURES

Figure 1: The generalized structural map of Salt Range/ Potwar Foreland Basin. 02

Figure 2: Base Map showing the seismic lines of the study area. 03

Figure 3: Flow Chart showing the various stages of Seismic Processing. 29

Figure 4: Flow Chart showing the Processing Sequence. 30

Figure 5: Interpreted Seismic Section of lines OX-S88-20. 34

Figure 6: Interpreted Seismic Section of lines OX-S88-24. 35

Figure 7: Interpreted Seismic Section of lines OX-S88-36. 36

Figure 8: Time Contour Map of Upper Eocene (Chorgali Formation). 38

Figure 9: Depth Contour Map of Upper Eocene (Chorgali Formation). 41

Figure 10: Flow Chart showing the Workflow of Petrophysical Evaluation. 42

Figure 11: Graph Showing Vsh and Depth. 45

Figure 12: Graph Showing Porosity Vs. Depth. 47

Figure 13: Graph Showing Sw with Depth. 48

Figure 14: Graph Showing comparison between Sw and Depth. 49

Figure 15: Graph Showing Sw with Porosity. 50

Figure 16: Graph Showing BVW with Porosity. 51

Figure 17:Chart Showing the Reserves Etimation Unit. 52

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LIST OF TABLES

Table 1: General Stratigraphy of Salt Range/Potwar Foreland Basin. 08

Table 2: Acquisition Parameters of lines OX-S88-20, OX-S88-23

& OX-S88-36. 25

Table 3: Receiver Parameters of lines OX-S88-20, OX-S88-23

& OX-S88-36. 26

Table 4: Spread Parameters of lines OX-S88-20, OX-S88-23

& OX-S88-36. 27

Table 5: The picked TWTs & Velocities to Calculate Average Velocities. 39

Table 6: The Zone of Interest . 43

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ABSTRACT

The seismic lines OX-S88-20, OX-S88-23, OX-S88-36 and Bhangali-01 well,

obtained from Directorate General of Petroleum Concessions (DGPC), was shot by

Occidental of Pakistan Inc. in the area of Bhangali (Eastern Salt Range/Potwar

Plateau). The direction of the dip lines is NorthWest to SouthEast and that of the

strike line is SouthWest to NorthEast. Two prominent reflectors namely Chorgali

Formation and Basement were marked on the seismic section on the basis of observed

reflection events. A fault was marked which continued along the Pre-Cambrian

basement. Two more thrust faults were marked which show a fault-propagating fold

in the form of the anticline of Bhangali. The TWT picked from the seismic section

was posted on the base map to make a time contour map of the Upper Eocene

Chorgali Formation, as it was continuing throughout the area. The seismic velocities

(Vrms), given in the velocity windows on the seismic section, were used to find the

average velocities of the Upper Eocene Chorgali Formation and the Pre-Cambrian

basement. These average velocities were then used to find the depths of the formation

for the depth contour map of the Upper Eocene Chorgali Formation. Well data of

Bhangali-01 was used to mark the thicknesses of the individual formations and to

perform petrophysical evaluation. The interpreted seismic sections and the contour

maps showed that the area was structurally deformed due to salt decollement and

compressional tectonic movements. Traps for hydrocarbons were developed in the

anticlines as they truncated against the basement fault. Salt probably moved into these

anticlines due to compressional movements. The Bhangali anticline was the

prospective zone and was the primary targets for oil exploration, where the depth of

the Upper Eocene formation was almost 3600m, favourable for drilling.

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ACKNOWLEDGEMENT

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