George Muia the “Turkana Grits”: Potential Hydrocarbon Reservoirs
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THÈSE / UNIVERSITÉ DE RENNES 1 sous le sceau de l’Université Européenne de Bretagne pour le grade de DOCTEUR DE L’UNIVERSITÉ DE RENNES 1 Mention : Sciences de la Terre Ecole Doctorale Sciences de la Matière présentée par George Muia Préparée à l’unité de recherche UMR 6118 Géosciences Rennes Observatoire des Sciences de l’Univers de Rennes Thèse soutenue à Rennes The “Turkana Grits”: le 24/07/2015 Potential Hydrocarbon devant le jury composé de : Jean-Luc POTDEVIN Reservoirs Professeur, Université de Lille 1 / rapporteur of the Northern Stéphane DUCROCQ Directeur de Recherche, and Central Kenya Rifts CNRS-Université de Poitiers / rapporteur Jean-Yves REYNAUD Professeur, Université de Lille 1 / examinateur Mathieu SCHUSTER Chargé de Recherche, CNRS Université de Strasbourg / examinateur Peter R. COBBOLD Directeur de Recherche Emérite, CNRS Université de Rennes 1/ examinateur Jean-Jacques TIERCELIN Directeur de Recherche, CNRS-Université de Rennes 1 / directeur de thèse Erwan HALLOT Maître de Conférences Université de Rennes 1 / co-directeur de thèse The “Turkana Grits”: Potential Hydrocarbon Reservoirs of the Northern and Central Kenya Rifts 3 Table of contents Acknowledgements 6 Abstract 8 General Introduction 9 Chapter I 21 1. Introduction 30 2. Field study, sampling and analytical methods 35 3. Regional background of the Central and Northern Kenya Rifts 37 3.1. Physiography and climate of the Central and Northern Kenya Rifts 37 3.2. Geological outline of the Kerio and Baringo Basins 40 3.3. Geological outline of the North Kerio Basin 43 4. The Kimwarer Formation 45 4.1. Lithostratigraphy 45 4.1.1. The “Lower Kimwarer Formation” 47 4.1.2. The “Upper Kimwarer Formation” 54 4.2. Structural framework of the Kimwarer Formation at the scale of the Kerio Basin 54 4.2.1. Seismic interpretation 56 4.2.2. Correlation of seismic packages to stratigraphic column of the Kerio Basin 59 4.2.3. Geological evolution of the Kerio Basin 59 4.3. Chronostratigraphic setting of the Kimwarer Formation 61 4.3.1. Volcanic units associated with the Kimwarer Formation 61 4.3.2. Dynamics of emplacement of the different volcanic units 77 4.3.3. Stratigraphy and correlations 78 4.3.4. Chronological setting of the Kimwarer Formation 79 4.4. Facies analysis, depositional processes and environments of the Lower and Upper Kimwarer Formation 81 4.4.1. Distal fluvial channel lithofacies associations 81 4.4.2. Alluvial fan lithofacies association 81 4.4.3. Floodplain lithofacies association 82 4.5. Post-depositional evolution of the Kimwarer Formation of the Kimwarer Formation, “Lower” and “Upper” 82 4.5.1. Texture 83 4.5.2. Detrital minerals 83 4.5.2.1. Quartz 83 4.5.2.2. Feldspars 83 4.5.2.3. Other detrital elements 84 4.5.3. Authigenic minerals 84 4.5.3.1. Zone 1 (Hematite-rich) 84 4.5.3.2. Zone 2 (Calcite-rich) 87 4.5.3.3. Zone 3 (Kaolinite-rich) 87 4.6. Origin of authigenic cements associated with the Lower Kimwarer Formation 87 4.6.1. Hematite cementation 87 4.6.2. Carbonate cementation (calcite) 88 4.6.3. Kaolinite cementation 88 4.6.4. Chronology of main diagenetic events 88 4.7. Porosity 88 4.8. Discussion 91 4.8.1. Palaeogeographical and climatic reconstructions 91 4.8.2. Implications on the reservoir potential of the Kimwarer Formation 92 4.9. Conclusion 93 5. The Kamego Formation 95 5.1. Lithostratigraphy 95 5.2. Chronostratigraphic setting of the Kamego Formation 101 5.3. Facies analysis, depositional processes and environments of the Kamego Formation 106 5.3.1. Distal fluvial channel lithofacies association 106 5.3.2. Floodplain lithofacies association 106 5.4. Post-depositional evolution of the Kamego Formation 107 5.4.1. Texture 107 4 5.4.2. Detrital minerals 107 5.4.2.1. Monocrystalline quartz 109 5.4.2.2. Polycrystalline quartz 109 5.4.2.3. Feldspars 111 5.4.2.4. Other detrital components 111 5.4.3. Authigenic minerals 111 5.4.3.1. Zone 1 (Calcite-rich) 111 5.4.3.2. Zone 2 (Hematite-rich) 111 5.4.3.3. Chronology of main diagenetic events 111 5.4.4. Porosity 112 5.5. Discussion 112 5.6. Conclusion 113 6. The Loriu Formation 114 6.1. Lithostratigraphy 114 6.1.1. The Loriu Section 116 6.1.2. The Kangabeiye Section 121 6.2. Chronostratigraphic setting of the Loriu Sandstone 122 6.3. Facies analysis, depositional processes and environments of the Loriu Sandstone, Loriu Section 127 6.3.1. Texture 128 6.3.2. Detrital minerals 128 6.3.2.1. Polycrystalline quartz 128 6.3.2.2. Monocrystalline quartz 128 6.3.2.3. Feldspars 130 6.3.2.4. Lithics, accessory minerals and matrix 130 6.4. Post-depositional evolution of the Loriu Sandstone, Loriu Section 130 6.4.1. Matrix/authigenic components 130 6.4.1.1. Zone 1 (Hematite-rich) 130 6.4.1.2. Zone 2 (Carbonate-rich) 131 6.4.1.3. Zone 3 (Kaolinite-rich) 131 6.4.2. Chronology of diagenetic events 132 6.4.3. Porosity 132 6.5. Facies analysis, depositional processes and environments of the Kangabeiye Section 134 6.5.1. Texture 134 6.5.2. Detrital minerals 135 6.5.2.1. Monocrystalline quartz 135 6.5.2.2. Polycrystalline quartz 135 6.5.2.3. Feldspars 135 6.6.2.4. Lithics, accessory minerals and matrix 135 6.6. Post-depositional evolution of the Kangabeiye Section 135 6.6.1. Matrix/authigenic components 135 6.6.1.1. Zone 1 (Calcite-rich) 135 6.6.1.2. Zone 2 (Kaolinite-rich) 135 6.6.2. Chronology of main diagenetic events 135 6.6.3. Porosity 135 6.7. Discussion 138 6.8. Conclusion 141 7. Discussion 143 7.1. The Lokone Sandstone, Lokichar Basin: the best hydrocarbon reservoir in the Kenya Rift? 145 7.2. The Kimwarer Formation, Kerio Basin (Figs. 17 and 18b; Table 15) 148 7.2.1. Lithology and depositional environments 148 7.2.2. Chronology 149 7.2.3. Reservoir characterization 149 7.2.4. Lateral and vertical extension of reservoirs 150 7.3. The Kamego Formation, Baringo Basin (Figs. 38 and 39; Table 15) 150 7.3.1. Lithology and depositional environments 150 7.3.2. Chronology 151 7.3.3. Reservoir characterization 151 7.4. The Loriu Sandstone, North Kerio Basin (Figs. 46 and 47; Table 16) 152 7.4.1. Lithology and depositional environments 152 7.4.2. Chronology 152 7.4.3. Reservoir characterization 152 7.5. The “Turkana Grits”: Potential reservoirs in the Kenya Rift? 153 Conclusion 155 References 166 Appendix 179 5 Acknowledgements Acknowledgements. While the research work that is contained in this manuscript is attributed directly to myself, this work in reality represents the combined effort of many people and institutions around the world, whose intellectual, financial and administrative contribution has resulted in the development and compilation of this manuscript, which is the substantive document representing my four year doctoral research programme at the Universite de Rennes 1. In appreciation, special mention must first go to the French Embassy in Kenya for granting me the scholarship, which formed the basis of my PhD programme. At the embassy, the attention which the cooperation attaches, Dr. Severine Fogel (2011- 2013) and Mrs. Sarah Ayito Nguema (2013 - 2015), attached to my research work is humbling and greatly appreciated. It is through this kind consideration that I was able to fully focus on the programme and complete the study within an acceptable time frame. My supervisor and co-supervisor, Dr. Jean-Jacques Tiercelin and Dr. Erwan Hallot are academicians par excellence. Their guidance in the course of my research work was invaluable. I am grateful for their academic guidance, which greatly helped me improve my field survey strategy, my research methodology as well as the overall structure of this manuscript. I am also grateful for the support that they both gave me towards the end of the writing of the manuscript; by proof-reading the text with me and ensuring all administrative affairs were in-order for me to submit my manuscript for review and consideration for defence. Special mention goes to Dr. Hallot who took on the bulk of my research supervision as well as the addressing all the administrative issues that developed during the time Dr. Tiercelin, my lead thesis supervisor, was convalescing. Data for my research project was collected from three, sparsely distributed sedimentary formations along the Kenyan Rift. The gathering of this data was made possible by the National Oil Corporation of Kenya (NOCK), which took up all the costs of my Kenyan-based fieldwork. Special mention must go to the NOCK, Chief Execu- tive Officer, Mrs. Sumayya Hassan-Athmani and the NOCK – Upstream General Manager, Mr. Kivuti Nyagah, who owing to the relevance of my research topic to the business functions of NOCK – Upstream, took special interest in my research work and supported me not only by putting company resources, such as the company field vehicle at my disposal during the data collection phase, but also allowing me ample time to conduct the fieldwork, analyse the data collected, write and refine the manuscript and finally defend the research work at the Universite de Rennes 1 where they were also members of my defense jury. I will be forever indebted to them for their kind consideration. The appreciation of the ‘in-field’ support from NOCK must also be extended to the two NOCK field drivers, Mr. Joel Kibor and Mr. Michael Mungai whose skills in safely navigating traffic in Nairobi and offroad in Kenya’s Rift Valley allowed me to amass an impressive dataset from the three sedimentary for- mations that I studied, essentially adding great value to the outcome of my work.