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Prediction of Clay Minerals and Grain-Coatings in Sandstone Reservoirs Utilising Ancient Examples and Modern Analogue Studies

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Prediction of Clay Minerals and Grain-Coatings in Sandstone Reservoirs Utilising Ancient Examples and Modern Analogue Studies Prediction of clay minerals and grain-coatings in sandstone reservoirs utilising ancient examples and modern analogue studies Thesis submitted in accordance with the requirements of the University of Liverpool for the degree in Doctor of Philosophy by Patrick James Dowey November 2012 Contents 1. INTRODUCTION ....................................................................................... 1 1.1 Background ........................................................................................ 1 1.2 Research objectives .......................................................................... 3 1.2.1 What factors are common to the formation of chlorite- coated sandstone reservoirs?................................................................ 4 1.2.2 How are clay minerals distributed in modern estuaries, and what processes and factors control their occurrence?............ 9 1.2.3 Do grain-coats occur in modern estuarine environments and how do they form? ........................................................................ 15 1.3 Methods ............................................................................................ 20 1.3.1 Modern estuarine studies ........................................................ 20 1.3.2 Field mapping & sample collection ....................................... 21 1.3.3 Sample preparation & storage ............................................... 22 1.3.4 Grain size analysis ..................................................................... 23 1.3.5 X-ray Diffraction (XRD) ............................................................. 24 1.3.6 Infrared Spectroscopy ............................................................. 28 1.3.7 Scanning Electron Microscopy (SEM) .................................... 29 1.4 Organisation of the thesis ............................................................... 31 2. PRE-REQUISITES, PROCESSES, AND PREDICTION OF CHLORITE GRAIN-COATINGS IN PETROLEUM RESERVOIRS: A REVIEW OF SUBSURFACE EXAMPLES .............................................................................. 38 2.1 Abstract ............................................................................................. 38 2.2 Introduction ...................................................................................... 39 2.3 Chlorite coat formation: Pre-requisites ......................................... 40 2.3.1 Diagenetic chlorite coats from precursor clay minerals .... 42 2.3.2 Diagenetic chlorite-coats formed from the dissolution of detrital grains .......................................................................................... 45 2.4 Dataset .............................................................................................. 46 2.4.1 Data collection ......................................................................... 47 2.4.2 Defining depositional environment ........................................ 48 2.4.3 Defining reservoir quality ......................................................... 50 2.4.4 Age and depositional latitudes .............................................. 53 2.4.5 Elemental compositions ........................................................... 53 2.5 Results ................................................................................................ 54 2.5.1 Depositional environment, reservoir quality and age......... 54 2.5.2 Age and depositional latitude ............................................... 56 2.5.3 Elemental composition, reservoir quality and depositional environment .................................................................... 58 2.6 Discussion .......................................................................................... 58 2.6.1 Depositional environment as a control ................................. 60 2.6.2 Depositional age as a control ................................................ 65 2.6.3 Paleolatitude ............................................................................. 66 2.6.4 Reservoir quality ........................................................................ 69 i 2.6.5 Elemental composition ............................................................ 70 2.6.6 Likely and unlikely chlorite-coat sandstone scenarios ........ 71 2.7 Conclusions ....................................................................................... 74 3. CLAY MINERALS IN A COLD CLIMATE: ORIGIN, MINERALOGY AND DISTRIBUTION OF CLAY MINERALS IN THE LEIRÁRVOGUR ESTUARY, SW ICELAND ................................................................................ 77 3.1 Abstract ............................................................................................. 77 3.2 Introduction: ..................................................................................... 78 3.2.1 Estuarine dynamics ................................................................... 79 3.2.2 Geochemical development ................................................... 82 3.3 Study area ........................................................................................ 85 3.3.1 Bedrock geology ...................................................................... 85 3.3.2 Glacial & sea level context ..................................................... 87 3.3.3 Catchment ................................................................................ 87 3.3.4 Estuary geomorphology .......................................................... 89 3.3.5 Clay mineral formation in Icelandic rocks & soils ................ 91 3.3.6 Hydrothermal clay mineral alteration.................................... 92 3.3.7 River water geochemistry ........................................................ 93 3.3.8 Offshore clay mineralogy ........................................................ 94 3.4 Materials and methods ................................................................... 95 3.5 Results .............................................................................................. 102 3.5.1 Sediment texture ..................................................................... 102 3.5.2 Clay mineral identification in estuary samples................... 105 3.5.3 Bedrock mineralogy ............................................................... 112 3.5.4 Glacial mineralogy ................................................................. 112 3.5.5 Riverbank soil mineralogy ...................................................... 115 3.5.6 Estuary clay mineral distributions .......................................... 116 3.5.7 Estuary non-clay mineral distributions .................................. 119 3.5.8 Mineral cross-plots & average values .................................. 123 3.5.9 Worm cast mineralogy ........................................................... 128 3.6 Discussion ........................................................................................ 131 3.6.1 Sediment texture ..................................................................... 131 3.6.2 Detrital & inherited mineralogy ............................................. 134 3.6.3 Non-clay minerals ................................................................... 140 3.6.4 Detrital & inherited mineral summary .................................. 141 3.6.5 Intra-estuarine processes ....................................................... 144 3.7 Conclusions:.................................................................................... 154 4. CLAY MINERALS IN THE SUN: MINERALOGY AND DISTRIBUTION OF CLAY MINERALS IN THE ANLLÓNS ESTUARY, GALICIA, SPAIN .......... 157 4.1 Abstract ........................................................................................... 157 4.2 Introduction .................................................................................... 158 4.2.1 Estuarine dynamics ................................................................. 159 4.2.2 Geochemical development ................................................. 162 4.3 Study area ...................................................................................... 165 4.3.1 Geology and tectonics ......................................................... 165 4.3.2 Weathering and soils .............................................................. 168 4.3.3 Coastal clay mineralogy ....................................................... 169 ii 4.3.4 Relative sea level history ........................................................ 171 4.3.5 Anllóns estuary catchment ................................................... 172 4.3.6 Anllóns estuary geomorphology .......................................... 173 4.4 Materials and methods ................................................................. 177 4.5 Results .............................................................................................. 181 4.5.1 Clay mineral identification .................................................... 181 4.5.2 Mineralogy of the bedrock ................................................... 185 4.5.3 Mineralogy of riverbank soil sediments ............................... 186 4.5.4 Estuary sediment texture ........................................................ 186 4.5.5 Estuary mineralogy ................................................................. 191 4.5.6 Relative estuary mineral data ............................................... 205 4.5.7 Estuary transects ..................................................................... 214 4.5.8 Mineral indices ........................................................................ 221 4.5.9
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