Subsurface Evaluation of Source Rock and Hydrocarbon Potential of the Anambra Basin, South Eastern Nigeria Iheanacho Princewill Ugochukwu DISSERTATION.COM Boca Raton Subsurface Evaluation of Source Rock and Hydrocarbon Potential of the Anambra Basin, South Eastern Nigeria Copyright © 2010 Fernando Iheanacho Princewill Ugochukwu All rights reserved. No part of this book may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without written permission from the publisher. Dissertation.com Boca Raton, Florida USA • 2010 ISBN-10: 1-59942-339-1 ISBN-13: 978-1-59942-339-5 CERTIFICATION I hereby certify that this report was prepared and written by Ugochukwu Princewill Iheanacho, Matriculation Number 142332, of the Department of Geology, Faculty of Science, University of Ibadan. ------------------------------ -------------------------------- Dr. M.E. Nton Date Supervisor i DEDICATION This report is dedicated to God Almighty for his divine mercies, grace and favour. ii ACKNOWLEDMENTS I want to acknowledge the Almighty Father for divine mercies and guidance throughout the research work. My profound gratitude also goes to my parents Rev. and Pastor Mrs P. C. Iheanacho for their support financially and otherwise, you have been a blessing to me. To my younger brother and sisters for their unalloyed support and advice, I want to say thank you. I also want to acknowledge my supervisor Dr. M. E. Nton for his support and guidance. My special thanks go to all lecturers of the department of geology for the knowledge acquired from them. My unreserved appreciation goes to my friends for their understanding, support and cooperation. I will like to mention but a few, Fummilayo Adedeji, Adedipe Olajide, Ashiru Ayodeji, Awarun Nike, Asije Alaba, my fiancée (Ijeoma Ezeogu), Emeka, my friends, colleagues and to all those that contributed to the success of the program, thanks for been there. I will not fail to thank the staffs of Weatherford Geochemical laboratory, Texas, U.S.A. and staffs Exxon Mobil Geochemical Laboratory, Eket for contributing to the success of this research. iii TABLE OF CONTENTS Page Certification……………………………………………………………………….………i Dedication…………………………………………………………………………………ii Acknowledgement………...………………………………………………………….…..iii Table of Contents…………………………………………………………………………iv List of Figures………………………………………………………………..………….vii List of Tables....................................................................................................................viii Appendix............................................................................................................................x Abstract…………………………………………………………………………………...xi CHAPTER ONE……………………………………………………………………………….1 INTRODUCTION……………………………………………………………….……………..1 1.1 General Statement…………………………………….…………………….………………1 1.2 Location and Accessibility………………………………..……………….……………….2 1.3 Relief and Drainage……………………………………..……………….…………………2 1.4 Weathering and Erosion……………………………………………….…………………..4 1.5 Climate and Vegetation………………………………....……………………………….5 1.6 Objectives of study……………………………………….………………………………..5 1.7 Scope of the study…………………………………………...……………………………..6 CHAPTER TWO …………………………………………………………………………….10 iv 2.0 Geological Setting and Basin Evolution………………………………………………….10 2.1 Geological Setting………………………………….……………………………………10 2.2 Basin evolution……………………………………………………………………………..10 2.3 Stratigraphy of the Anambra Basin…………...…………………………………………16 CHAPTER THREE...................................................................................................................27 3.0 SAMPLING AND ANALYTICAL METHODS………….…………………………...27 3.1 Lithostratigraphic Description…………………………..……………………………….27 3.2.0 Laboratory Analysis and Method…………………………..…...……………………30 3.2.1 Total Organic Carbon (TOC) Content…………………………………………………30 3.2.2 Rock Eval Pyrolysis………………………………………………..………………………..……….…..30 3.2.3 Soluble Organic Matter (SOM)………………………………...……………………….32 3.2.4 Gas Chromatography of Whole Oil…………………….…………………………….33 3.2.4.1 CPI( Carbon Preference Index) and OEP (Odd to Even Predominance)……...…..34 3.2.5 Gas Chromatography Mass spectrometer (GC/MS)……………………….…….……34 3.2.5.1 Liquid Chromatography…………………………………………………………....…35 3.2.5.2 De-asphaltening……………………………………….………………………………..35 3.2.5.3 Separation of the pentane soluble fraction (PN)………..……….…………………...35 3.2.5.4 Gas Chromatography Mass Spectrometry……………..………..………………...…36 3.2.5.5 Calculated Aromatic Biomarker Parameters…………………………….……...….37 CHAPTER FOUR……………………………………………………………………...……..38 4.0 Result Interpretation and Discussion……………………………………….…….…….38 4. 1 Organic Matter Quantity………………………………….………………………...…...38 4.2 Organic Matter Type/Quality…………………………………….………………………42 v 4.3 Thermal Maturity………………………………………………………………………45 4.4 Biomarker Distribution……………………………………………………………..….48 4.4.1 Saturated Biomarkers Distribution............................................................................48 4.4.2 Aromatic Biomarkers Distribution…………….……………………………….…..63 4.5 N- Paraffin/Isoprenoid Ratios………………………………………….………….….66 4.5.1 Carbon Preference Index (CPI) and Odd-Even Predominace (OEP). …………66 4.6 Source of Organic Input…………………………………………………...….…..….67 4.7 Palae-odepositional Environment…………….………………………….……..………….….72 CHAPTER FIVE…………………………………………….…………………….……..75 5.1 SUMMARY AND CONCLUSIONS………..…………………………………..…75 5.2 Recommendations…………………………………………………………………...76 REFERENCES……………………………………………………………….……….…77 APPENDIX………………………………………………………………………………97 vi List of Figures Figure Page 1.1 Geological Map of Anambra Basin showing the study area…………………..……...............2 2.1 Geologic Map of Southeastern, Nigeria …………………………………..…………………13 2.2: Sedimentary basins in Nigeria……………………………………………………..………..14 2.3 Geologic Map of Anambra Basin…………………………………..……………………..…15 2.4: Regional Geologic Map of Anambra Basin and Niger Delta showing the Stratigraphy of the Anambra Basin ……………………………………..…………………………………………...22 2.5: Cross section of the Lower Benue Trough showing the synclinal Anambra Basin………...24 3.1: Lithostratigraphic log of Enugu 1325 well……………...………….……………….……...28 3.2: Lithostratigraphic log of Enugu 1331 well…………………………….………………...…29 4.1: A plot of S1+S2(mg/mg rock) and TOC(wt%)……………………………….………...….40 4.2: A plot of SOM and TOC(wt%)…………………………………………………...…….....41 4.3: A plot of Hydrogen Index against Oxygen Index for the studied wells...............................42 4.4: A plot of Hydrocarbon potential against TOC for the studied wells……………….............43 4.5: A plot of EOM (ppm) and TOC(wt%)……………………………………………………...44 4.6: A plot of Hydrogen index against Tmax for the studied wells .............................................45 4.7: A plot of Production Index against Tmax for the studied wells…………………………...46 4.8: Mass Chromatogram for M/z191 showing the distribution of terpanes and hopanes for EN 1325(P1)…………………………………………………………………………………………49 4.9: Mass Chromatogram for M/z191 showing the distribution of terpanes and hopanes for EN 1325(P3)……………………………………..……………………………………………….....50 vii 4.10: Mass Chromatogram for M/z191 showing the distribution of terpanes and hopanes for EN 1331(V2)…………………………………………………………..……………………………..51 4.11: Mass Chromatogram for M/z191 showing the distribution of terpanes and hopanes for EN 1331(V3)……………………………………………..…………………………………………..52 4.12: Mass Chromatogram for M/z191 showing the distribution of terpanes and hopanes for EN 1331(V5)…………………………………………………………………………………………53 4.13: Mass Chromatogram for M/z191 showing the distribution of terpanes and hopanes for EN 1331(V6)…………………………………………………………………………………………54 4.14: Mass Chromatogram for M/z191 showing the distribution of terpanes and hopanes for EN 1331(V3)…………………………………………………………………………………………55 4.15 :Mass Chromatogram for M/z217 showing the distribution of steranes for EN 1325(P1)…………………………………………………………………………………………56 4.16 : Mass Chromatogram for M/z217 showing the distribution of steranes for EN 1325(P3)………………………………………………………………………..………………..57 4.17: Mass Chromatogram for M/z217 showing the distribution of steranes for EN 1331(V2)………………………………………………………………..……………………….58 4.18: Mass Chromatogram for M/z217 showing the distribution of steranes for EN 1331(V3)………………………………………………………………………………………...59 4.19: Mass Chromatogram for M/z217 showing the distribution of steranes for EN 1331(V5)………………………………………………………………………………………...60 4.20: Mass Chromatogram for M/z217 showing the distribution of steranes for EN 1331(V6)………………………………………………………………………………………...61 4.21: Mass Chromatogram for M/z217 showing the distribution of steranes for EN 1331(V8)……………………………………………………………………..………………….62 4.22: m/z 170 mass chromatogram showing the distributions of naphthalene of representative sample EN1331(V5)………………………….………………………………………………….63 4. 23: Gas chromatogram for EN 1331(V2)…..………….…………….………………………..68 viii 4.24: Gas chromatogram for EN 1325(P3)……………………………....………………………68 4.25: Gas chromatogram of EN 1325(P1).....................................................................................69 4.26 : Gas chromatogram of EN 1331(V5)...................................................................................69 4.27 : Gas chromatogram of EN 1331(V6)...................................................................................70 4.28: A ternary plot of C27, C28 and C29 showing source of organic matter…..………………71 4.29: A plot of Ts/(Ts+Tm) showing the environment in which the organic matter was deposited………………………………………...……………………………………….………72