PETROPHYSICAL EVALUATION OF RESERVOIR ROCKS WITH SPECIAL EMPHASIS ON LOG-DERIVED CATION

EXCHANGE CAPACITY OF SHALY SANDS OF KADANWARI-01, KADANWARI-03 AND KADANWARI-10 OF KADANWARI

GAS FIELD CENTRAL INDUS BASIN, PAKISATN

MS GEOPHYSICS SYNOPSIS (2012 – 2014)

Supervised by

Dr.Mubarik Ali

Co-supervised by

Prof.Mujeeb Ahmed

Submitted by

Kamran Ramzan

Enroll. # 02-262122-007

Reg.#32399

FACULTY OF EARTH & ENVIRONMENTAL SCIENCES BAHRIA UNIVERSITY KARACHI

CONTENTS

1. INTRODUCTION 2

2. LOCATION OF STUDY AREA 3

3. OBJECTIVE 4

4 .JUSTIFICATION AND LIKELY BENEFITS 5

5. DATA REQUIRED 5

6. METHODOLOGY 6

7. CENTRAL INDUS BASIN 7

8 .STRAITIGRAPHY OF CENTRAL INDUS BASIN 8

9. TIME PLAN FOR THESIS 10

REFERENCES 11

FIGURES

LOCATION MAP 2

SATELITE IMAGERY OF STUDY AREA 3

STRATIGRAPHY OF THE AREA 9

TABELS

TIME PLAN FOR THESIS 10

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1. Introduction

The southernmost part of the Indus basin is known as Lower Indus basin, Badin Block or adjacent areas are also part of this basin. The approximate limits are south of Khairpur High and extends into the Arabian Sea, Petroleum exploration started in back in 1950’s in the Lower Indus basin. The first gas discovery was Sari-Hundi in Kirthar Range; district Dadu whereas first major oil struck in early 1980's at Khaskheli, near Badin where several large and small oil and gas fields have been discovered since then.

The Lower Indus basin can be divided into areas where Neogene to Cretaceous rocks are exposed; western part along Kirthar Range and into the areas where no surface geology exposed or minor at lesser extent geological units of Neogene to Pleistocene are cropping out; Badin Block are areas nearby all are without surface geological expression.

In Badin area, early Cretaceous Sembar Formation is considered as the principal source rock whereas clastics of the Early Cretaceous age Lower Goru Formation is the main reservoir.

Traps in the Badin area is generally tilted fault blocks associated with normal faults developed during Late Cretaceous and Early Paleocene rift phase. The cap rock is invariably all the time is impermeable marl and shale sequence of Upper Goru Formation whereas the Earlu Paleocene volcanic flow, known as Deccan basalt, believed to be the reason for providing increasing temperature to the underlying sediments including source rock (Sembar and Goru)which help to generate hydrocarbon from the source and the process of the oil expulsion started to take place.

Oil of Badin is very high quality, it is sweet and paraffinic with API gravity range from 32 to 55 and easy to flow. Though oil in the southern part of the Badin area found to be heavy and waxy. The oil reservoir depth is from 2000ft to 13500ft. Khaskeli, Golarchi, Bhatti, Turk, Tando Alam, Bobby and Pasakhi are the large oil and gas fields of this area.

Badin area is considered favorable for oil and gas whereas western part of the Lowwer Indus Basin (Kirthar hills and mountains)and adjacent area known for its gas potential. In Lower Indus, so far more than 12TCF (trillion Cubic feet# gas reserves and more than 100 million barrels oil have been discovered in Lower Indus Basin whereas more than 90% oil production is from Badin area. The oil operators in this region are, OGDCL and BP. Khaskeli is the first and the largest oilfield in Badin Area so far.

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2. Location of study areaKadanwari Gas Field, located in the Central Indus Basin Sindh province of Pakistan, as shown in Map and satellite image below.

Figure 1 : Map showing location of study area

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Figure 2 : Satellite Imagery of Kadanwari

3. Objectives

The main purpose of well logging is the identification and evaluation of the potential of

hydrocarbon bearing formations. The main objectives of this thesis is evaluation of hydrocarbons of Kadanwari 01 , Kadanwari 03 and kadanwari 10 of Kadanwari gas field Central Indus basin and correlation of these wells with the help of wireline logs with Special emphasis of this thesis is on the potential of a zone is measured by estimating its water saturation, Sw.

In past clean (shale free) formations, water saturation can be calculated using the well-known Archie’s equation. Archie’s equation is based on the assumption that brine is the only electric conductor in the formation. However, this is not the case in shaly sand formations where ions associated with clay minerals also transport electricity. The presence of clay minerals results in reduction of the SP deflection, ESP and an increase

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in the rock conductivity, Ct. Hence, cation exchange capacity, which represents the clay ability to conduct electricity, has a considerable effect on the evaluation of hydrocarbon-bearing formations. Consequently, the use of clean sand models to estimate the water saturation results in inaccurate estimation of the potential of hydrocarbon zones. The result is usually higher water saturation than actually present in the formation.

During this study we Carry out petrophysical interpretation of the provided wireline logs of mentioned wells , which are as follow

i. Calculate the volume of shale.

ii. Detrmine the porosity and permeability of reservoirs.

iii. Lithology

iv. Determine Water saturation and Hydrocarbon saturation.

v. Log-derived cation exchange capacity of shaly sands.

vi. Net pay thickness

vii. Correlations of logs

4. Justification and Likely Benefits

We have exploited almost all of the structural traps and zone of interest of the study area, Now we are approach the log-derived cation exchange capacity of shaly sands techniques for water saturation determination to re optimized reservoir of the study area. By integrating petrophysical analysis I will establish reservoir characteristics (porosity, permeability), Hydrocarbon saturation and other petrophysical characteristics.

5. Data Requirement

With the permission of Directorate General of Petroleum Concession the data will be collected from LMKR. The data require for the completion of research are as follow; complete suite of LAS (Log Ascii Standard) file of wireline log data, Final well report and tools e.g. Petrel/kingdom suit and Geographix suit.Open hole wireline logs of Kadanwari 01, Kadanwari 03 and Kadanwari 10 wells , which includes

a. Sonic log

b. Density log

c. Gamma ray log

d. Spontaneous Potential log

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e. Resistivity log

f. Neutron log

g. Bhorehole geometry log

6. MethodologyThe method use to detrmine for petrophysical characteristics are as follow Raw log curves

Volume of shale

Lithology

Porosity & Permeability

Saturation of water

Saturation of hydrocarbon

Net pay thickness

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Conclusion

7. Central Indus basin

The Central Indus basin is separated by Jacobabad and Mari Kandhkot highs (Sukkur Rift) from Southeren Indus basin.The Central Indus basin is divided into three main units shown in figure 3.

1. Punjab Platform

2. Sulaiman Depression

i. East sulaiman depressionii. Zindapir Inner Folded Zone iii. Mari Bugti Inner fold Zone

3. Sulaiman Fold Belt

Figure 3 : Central Indus basin and the subdivisions into petroleum zone (after Raza et al, 1989)

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7.1 Punjab Platform

Kadri, (1995) describes this part as the eastern segment of Central Indus Basin where

no surface outcrops of sedimentary rocks are present. Tectonically it is a broad

monocline dipping gently towards the Sulaiman Depression. Punjab Platform is

tectonically the least affected area because of its greater distance from collision zone. A

number of wells have been drilled on this platform. The stratigraphic sequence

established on the basis of these wells revealed some of the most significant

stratigraphic pinch outs in Pakistan.

7.2 Sulaiman Depression

This depression is longitudinally oriented area of subsidence; it becomes arcuat and

takes up a transverse orientation along its southern rim.This depression was formed as

result of collision between two plates. The western flank of depression includes

Zindapir Inner Folded Zone while Mari Bugti Inner Folded Zone lies in the south , to the

east it merges into Punjab Platform. The seismic evidence shows some buried anticlines

(e.g. Ramak) which may have been formed due to the flow of Eocene shales.

7.3 Sulaiman Fold Belt

This is a major tectonic feature in the proximity of collision zone and, therefore,

contains a large number of disturbed anticlinal features.The most important

lithostratigraphic variations observed in Sulaiman Depression and the Fold Belt are in

Paleocene/Eocene. This period marks the facies changes from north to south and east

to west. The reason for this variation is believed to be the presence of a number of new

basins at that time, created due to the collision of plates and their irregular and non-

uniform coalescence.

8. Stratigraphy of the Central Indus basinThe generalized stratigraphy of central Indus basin ranges from Mesozoic formations to recent.

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Figure 4- Generalized Stratigraphic Column of Central Indus basin

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9. TIME PLAN FOR THESIS

Work Flow Feb Mar-April April-May May-Jun Jun-July July-Aug

Proposal submission

Data collection

Studying log curves

Manual interpretation

Data processing

Data interpretation

Geographix/Petrel

Correlation of wells

Thesis writing

Thesis submission

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References:

1. Nasir Ahmed , Giacomo Spadini , Arshad Palekar , M. Asim Subhani, Porosity prediction using 3D Seismic inversion Kadanwari Gas field , Pakistan ,Pakistan journal of hydrocarbon research Vol. 17, (June 2007),p.95-102.

2. Kadri, I.B., 1995, Petroleum Geology of Pakistan, Pakistan Petroleum Limited. Karachi, p.33.

3. Anna Berger , Susanne Gier and Peter Krois, Porosity preserving chlorite cement in shallow marine volcani-clastic sandstones : evidence from Cretaceous sandatones of the Sawan gas field, Pakistan, AAPG Bulletin, V93 , No 5 , may 2009, P.596.

4. Mahmud S.A and Ahmed Shamim (2009), “Reservoir Potential of Lower Nari Sandstones in Southern Indus Basin and Indus Offshore” Presented on SPE/PAPG Annual Technical Conference 2009.

5. M. Anwar Moghal, M. Ishaq Saqi, and M. Athar Jamij 2012: Hydrocarbon Potential of Tight Sand Reservoir (Pab Sandstone) in Central Indus Basin-Pakistan.

6. Khattak F G., Shafeeq M., Ali S M.,Regional trends in porosity and permeability of reservoir horizons of Lower Goru formation, Lower Indus Basin, Pakistan. Pakistan Journal of Hydrocarbon Research Vol.11, (January 1999).p.37-50, 8 Figs., 3 Tables.

7. Shahid M A., Rahman S., Shah S H. , Haq M Z. , Palekar A H., Identification of Low Resistivity Hydrocarbon Bearing Reservoirs in Lower & Middle Indus Basin Using Available Wireline Logs.PAPG-SPE ATC, 2008.

8. Wandrey C J., Law B E., and Shah H A., Sembar Goru/Ghazij Composite Total Petroleum System, Indus and Sulaiman-Kirthar Geologic Provinces, Pakistan and India. U.S. Geological Survey Bulletin 2208-C.

9. Lau, M.N. and Bassiouni Zaki, “Development and Field Applications of Shaly

Sand Petrophysical Models Part I: The Conductivity Model,” SPE Publications,

SPE 20386, 1990.

10. Demircan, G., Estimation of Shale Cation Exchange Capacity Using Log Data: Application to the Drilling Optimization, Louisiana State University M. S. Thesis, 2000

11. Petrophysics MSc Course Notes by Dr. Paul Gloverhttp://www2.ggl.ulaval.ca/personnel/paglover

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