Ain Shams University

Faculty of Science

Geophysics Department

Reservoir characterization of Pliocene

sand using quantitative seismic techniques

and well logs at west offshore Nile Delta,

Egypt

A thesis submitted for the degree of Master of Science as a

partial fulfillment for the requirements of Master degree of

Science in Applied Geophysics. By

Esraa Mahmoud Azmy Abdel Hamid B.Sc. in Geology and Geophysics

Faculty of Science – Ain Shams University, 2011

To Geophysics

Department Faculty of

Science

Ain Shams University

Supervised by

Prof. Dr. Said Abdel- Maaboud Aly. Head of Geophysics Department. Faculty of

Science – Ain Shams University

Dr. Azza Mahmoud Abd El-Latif El-Rawy Lecturer of Geophysics

Mr. Maged Mohamed Fahim. Senior Geophysicist- bp Egypt.

Geophysics department – Faculty of Science – Ain Shams University

Cairo – 2015

Note

The present thesis is submitted to faculty of Science, Ain Shams University in partial

fulfillment for the requirements of the Master degree of Science in Geophysics.

Beside the research work materialized in this thesis, the candidate has attended ten post-

graduate courses for one year in the following topics:

1. Geophysical field measurements

2. Numerical analysis and computer programming

3. Elastic wave theory

4. Seismic data acquisition

5. Seismic data processing

6. Seismic data interpretation 7. Seismology

8. Engineering seismology

9. Deep seismic sounding

10. Structure of the earth

She successfully passed the final examinations in these courses.

In fulfillment of the language requirement of the degree, she also passed the final

examination of a course in the English language.

Prof. D. Salah Eldin Abdel Wahab

Mohamed Mousa Head of Geophysics Department

I

Acknowledgments

After thanks to Allah, I would like to thank my direct supervisor

Prof. Dr. Said Abdel- Maaboud Aly, professor of Geophysics, Faculty of

Science, Ain Shams University, for his guidance and his effort

I deeply thank Dr. Azza Mahmoud Abd El-Latif El-Rawy,

Lecturer of Geophysics, Faculty of Science, Ain Shams University, for

sharing with the idea of this study, her effort and leading comments in this

work and reviewing the write up.

Also I deeply thank Mr. Maged Mohamed Fahim, Senior

Geophysist, BP Egypt, for his effort, and his experience and insightful

comments greatly improved the quality of my work.

I would like also to thank BP-Egypt for providing the data and I

deeply thank everyone that helped me to finish my work.

Finally I dedicated this work to my family and I actually thank them

for their patience, support and encouragement.

II

Abstract

Nile Delta is a complex and difficult province for hydrocarbon

exploration, the Pliocene channel prospect is located in the North Alexandria

Block B concession and is a complex, elongated, highly sinuous, deeply

incised, mature Pliocene turbidite channel system that extends 15 Km across

the West Nile Delta. The study area is affected by three main fault trends and

the main sand reservoir is Kafr Elsheik Formation.

3D traditional seismic interpretation was done for identification of the

channel top and base and studying the lateral distribution of the channel. The

Pliocene channel prospect is a complex, elongated, highly sinuous, deeply

incised that extends from NW to SE and it is split into three segments by

NE-SW and E-W faults.

Then, the channel was evaluated by studying the channel

petrophysical parameters to get the net to gross value (NTG) of the reservoir

and getting the value of the GIIP and recoverable resources of the interested

reservoir. X1 Well consists of three pay zones from four sand packages

while X2 Well that consists of one sand package. The GIIP value equal

2.1462*1010 (SCF), and the Recoverable Resources

equal 15.0234*109(SCF). Channel modeling was done to identify the channel and its internal

geometry by using different techniques of attributes such as amplitude

extraction, coherence, spectral decomposition technique and Direct

Hydrocarbon Indicators such as bright, dim and flat spot are clarified within

the channel by the analysis where the north well is brighter than the south

well and the two wells have gas water contact (flat spot) and the dimming

problem within the channel is solved by the modeling.

Amplitude versus offset technique was used to evaluate the Pliocene

channel to get the class type using Rutherford and Wiliam‘s classification

that is class 3 increasing of the amplitude with the offset in the negative

direction and by using EEI technique that discriminate between the lithology

and the fluid where the fluid angle equal 45° and the lithology is

90°. The results of using Extended Elastic Impendence (EEI) technique

showed that EEI is worthy effort to highlight the difference between reservoir

and non-reservoir to identify hydrocarbon area.

List of Contents

Acknowledgments ……………………………………………....I

Abstract……………………………………………………........II

List of Contents………………………………………………..III

List of Tables……………………………………………..…...VII

List of Figures………………………….................................VIII

Chapter one: Introduction……………………….………..…....1 1.1 Location of the Study Area……………………………………………....1 1.2 Aim of Study………………………………………………............……..2

1.3 Available Data…………………………………………………………...3

1.4 Methodology and Techniques ………………………………………..…4

Chapter Two: Regional Geologic Setting…………..………….6 2.1 Introduction………………………………………………………………6 2.2 Regional Stratigraphy………………………………………….………...8

2.2.1 Pre-Miocene Stratigraphy………………………………….….……10

2.2.2 Miocene Stratigraphy…………………………………….…………12 2.2.2.1 Qantara Formation-Early Miocene (Aquitania-Burdigalian)…...12

2.2.2.2 Sidi-Salem Formation (Serravallian-Tortonian)……………..…13

2.2.2.3 Qawasim Formation (Lower Messinian)……………………….13

2.2.2.4 Abu Madi Formation (Upper Messinian)…………………...…..14

2.2.2.5 Rosetta Formation (Messinian)……………………………..….14

2.2.3 Pliocene-Pleistocene Stratigraphy……………………….…...……..15

2.2.3.1 Kafr El Sheikh Formation (Pliocene)……………………….….16

2.2.3.2 El Wastani Formation (Upper Pliocene)………………………..17

2.2.3.3 Mit Ghamr Formation (Pleistocene)…………………………….18

2.2.3.4 Bilqas Formation (Holocene)……………………………..…….18

2.3 Structural Framework of the Nile Delta………………………………...18

2.3.1 NW-SE Temsah Fault Trend…………………………...…….……..21

2.3.2 NE-SW Rosetta Fault Trend………………………………………..22

2.3.3 East-West Coastal Faults…………………………………..……….23

2.3.4 Minor Faul Trends…………………………….……………………23

2.4 Structural Evolution of the study Area……………………………..…..24

2.5 Tectonic History of Offshore Nile Delta……………………………….26

2.5.1 Cratonic sag stage…………………………………………………..28

2.5.2 Rift stage…………………………………………………………....28

2.5.3 Passive margin stage………………………………………………..29

2.5.4 Syrian Arc stage………………………………………………...…..30

2.5.5 Gulf of Suez Rifting and Red Sea Opening Stage………….…..…..32

2.5.6 Tertiary deltaic sedimentation……………………………………...32

2.5.7 Messinian Crisis…………………………………………………….34

2.5.8 Pliocene-Pleistocene Delta Progradation.…………………………..35

2.6 Submarine Fans/Turbidite Systems…………………………………….35

2.6.1 Defining Some Terminology…………………………….…………37

2.6.2 Fine-Grained Turbidite System…………………………………….41

2.6.2.1 Sheet sandstones ……………………………………………….43

2.6.2.2 Canyon and channel-fill sandstones…………………….………44

2.6.2.3 Levee deposits ……………………………………………...…..49

2.6.3 Architectural Hierarchy and Anatomy of Submarine Slope Channel

Complex…………………………………………………………..51

Chapter Three: 3D Seismic Interpretation for Delineation the Pliocene Channel Complex………....55 3.1 Introduction……………………………………………………………..55 3.2 Available Data………………………………………………...………..56

3.2.1 Seismic Data…………………………………………...……….…..56

3.2.1.1 Acquisition Parameters for MAZ Seismic Surveys…………....58

3.2.1.2 Processing Parameters for MAZ Seismic Survey…………..….59

3.3 Data Quality Control (Data Conditioning)……………………………..60 3.3.1 Phase and Polarity of Seismic Data…………………………..……60

3.3.2 Seismic Resolution (Wedge Model)…… …………...…………….63

3.4 Seismic to Well Ties……………………………………………………67

3.4.1 Conditioning, Editing and Analysis of Well logs……………….…68

3.4.2 Data Assessment and Datum Determination………………………68

3.4.3 Wavelet Extraction ………………………………………………68

3.4.4 Synthetic Generation ……………………………………………..69

3.5 Seismic Interpretation……………………………………………..……74

3.5.1 Interpretation of the Pliocene Channel…………………….………75

3.5.1.1 Interpretation of the Top Pliocene Channel…………………....75

3.5.1.2 Interpretation of the Base Pliocene Channel…………………..79

3.5.1.3 Faults Interpretation affecting the Pliocene Channel………..…83

3.5.2 Pliocene Channel Complex Display and Description……………...85

Chapter Four: Petrophysics Analysis………………..……….90 4.1 Introduction…………………………………………………………..….90 4.2 Available Data…………………………………………………………..91

4.3 Evaluation of Petrophysical Properties of the Studied Wells………….95 4.3.1 Determination of Shale Volume …………………………………..96

4.3.2 Determination of Formation Porosity……………………………...97

4.3.2.1 Sonic Porosity …………………………………………………97

4.3.2.2 Density Porosity ……………………………………………….98

4.3.2.3 Neutron Porosity ………………………...…………………….99

4.3.2.4 Combination Neutron-Density logs……………………....….100

4.3.2.4.1 Total Porosity …………………………………….………100

4.3.2.4.2 Effective Porosity ………………………………………..100

4.3.3 Determination of Fluid Saturations ………………………..……100

4.3.3.1 Water Saturations Determination …………………………….101

4.3.3.2 Hydrocarbon Saturations Determination …………………….102

4.4 Determination of Net Pay and Net Reservoir Thicknesses…...……….103

4.5 Lithologic Identification…………………………………………..…...109

4.5.1 Neutron- Density Crossplot……………………………...……….109

4.6 Depositional Model of the Pliocene Channel…………………………114

4.7 Gas In Place and Recoverable Volumes………………………………115

Chapter Five: Seismic Attributes Characterization for

Pliocene Channel …………………………………………….118 5.1 Introduction…………………………………………………………. 118 5.2 Seismic Attributes Classifications………………………………...…..120

5.3 Amplitude Attributes Extraction…………………………………..….121

5.3.1 RMS Amplitude Attribute…………………………………….….122

5.3.2 Maximum Negative Amplitude Attribute…………………..….....122

5.3.3 Channel Internal Geometry Based on Amplitude Variations ……125

5.4 Coherence Attributes Estimation …………………………………..…129

5.4.1 Coherence Algorithms…………………………………………....130

5.5 Spectral Decomposition Attributes Estimation…………….……….....136

5.5.1 Physical Concept of Spectral Decomposition…………………….137

5.5.2 Technical Description and Workflow of Spectral Decomposition.140

5.5.3 Imaging Pliocene Channel Complex by Spectral Decomposition

Attribute Maps..............................................................................145

5.6 Direct Hydrocarbon Indicators (DHI)……………………………..….152

5.6.1 Physical Concept of Direct Hydrocarbon Indicators……….……..154

5.6.2 Direct Hydrocarbon Indicators for Pliocene Channel Complex…..158

5.6.2.1 Bright and Dim Spots Attributes……………………………..159

5.6.2.2 Flat Spot Attribute……………………………………………160

5.6.2.3 Dimming Problem in the Southern Part of the Pliocene Channel

Complex…………………………………………………………164

Chapter Six: Lithology-Fluid Separation Based on AVO and

EEI Modeling………………………………..……………..…169 6.1 Introduction…………………………………………………….….…..169 6.2 Historical and Physical Background of AVO………………………....171

6.2.1 Physical Principles of AVO……………………………………….172

6.2.2 Classification of AVO……………………………………………..176

6.3 Available Data……………………………………………………..….181

6.4 AVO Analysis Workflow……………………………………………..181

6.4.1 Seismic Angle Stacks Conditioning (QC)…………………….…..184

6.4.1.1 Frequency Filtering………………………..………………….184

6.4.1.2 Events Alignment (Trim Statics) ……………………….........185

6.4.1.3 Amplitude Balancing/Scaling………………………………...186

6.4.2 AVO-Response of Gas Sand …………………………………...…187

6.5 Lithology-Fluid Discrimination……………….…………………..…..191

6.5.1 Theoretical Background……………………………………….…..191

6.5.1.1 Elastic Impedance (EI)………………………………..………191

6.5.1.2 Extended Elastic Impedance………………………...………..193

6.5.2 EEI Method for Discriminating between Lithology and Fluids

Anomaly…………………………………………………………………..197

Chapter Seven: Summary and Conclusion…………….…...207

Appendix A …………………………………………………..212

References…………………………………………………….216

Arabic Summary

VII

List of Tables

Table (4.1): The used parameters in calculating shale volume……………..96

Table (4.2): The used parameters in calculating net pay and net reservoir

thicknesses………………………………………………………………...103

Table (4.3): Calculation of average Vsh, Porosity, water saturation and

N/G for X1 well…………………………………………………………....108

Table (4.4): Calculation of average Vsh, Porosity, water saturation and

N/G for X2 well…………………………………………………………….108

Table ( 5.1): Pertrophysical parameters for X1 and X2 wells…………….165