Reservoir Modelling: A Practical Guide

The essential resource to an integrated approach to reservoir modelling by highlighting both the input of data and the modelling results Reservoir Modelling offers a comprehensive guide to the procedures and workflow for building a 3-D model. Designed to be practical, the principles outlined can be applied to any modelling project regardless of the software used. The author — a noted practitioner in the field — captures the heterogeneity due to structure, stratigraphy and sedimentology that has an impact on flow in the reservoir. This essential guide follows a general workflow from data QC and project management, structural modelling, facies and property modelling to upscaling and the requirements for dynamic modelling. The author discusses structural elements of a model and reviews both seismic interpretation and depth conversion, which are known to contribute most to volumetric uncertainty and shows how large-scale stratigraphic relationships are integrated into the reservoir framework. The text puts the focus on geostatistical modelling of facies and heterogeneities that constrain the distribution of reservoir properties including porosity, permeability and water saturation. In addition, the author discusses the role of uncertainty analysis in the static model and its impact on volumetric estimation. The text also addresses some typical approaches to modelling specific reservoirs through a mix of case studies and illustrative examples and: Offers a practical guide to the use of data to build a successful reservoir model Draws on the latest advances in 3-D modelling software Reviews facies modelling, the different methods and the need for understanding the geological interpretation of cores and logs Presents information on upscaling both the structure and the properties of a fine-scale geological model for dynamic simulation Stresses the importance of an interdisciplinary team-based approach Written for geophysicists, reservoir geologists and petroleum engineers, Reservoir Modelling offers the essential information needed to understand a reservoir for modelling and contains the multidisciplinary nature of a reservoir modelling project. 

Table of Contents:
Preface xiii 1 Introduction 1 1.1 ReservoirModelling Challenges 3 1.2 Exploration to Production Uncertainty 4 1.3 Content and Structure 6 1.4 What is a Reservoir Model? 9 1.4.1 ReservoirModel Design 12 1.5 The ModellingWorkflow 13 1.5.1 Project Planning 15 1.5.2 What Type of Model Are You Planning to Build? 16 1.6 An Integrated Team Structure for Modelling 17 1.7 Geostatistics 19 1.8 Data Sources and Scales 22 1.9 Structural and Stratigraphic Modelling 25 1.10 FaciesModelling 25 1.11 Property Modelling 26 1.12 Model Analysis and Uncertainty 27 1.13 Upscaling 29 1.14 Summary 29 2 Data Collection and Management 31 2.1 Seismic Data 33 2.1.1 Horizons 33 2.1.2 Fault Sticks and Polygons 33 2.1.3 Surface Intersection Lines 34 2.1.4 Seismic Data Volume 34 2.1.5 Velocity Model 34 2.2 Well Data 34 2.2.1 Wellbore Path 34 2.2.2 Computer-Processed Interpretation (CPI) Logs 36 2.2.3 Core Descriptions 39 2.2.4 Core Photographs 39 2.2.5 Core Plug Data 39 2.2.6 Reservoir Zonation 41 2.2.7 Pressure Data 41 2.3 Dynamic Data 41 2.3.1 Fluid Data 41 2.3.2 Well Test Data 42 2.4 Important Specialist Data 42 2.4.1 Special Seismic Cubes and Seismic Test Lines 42 2.4.2 SCAL Data 43 2.4.3 Borehole Image Logs and Interpretations 43 2.5 Conceptual Models 43 2.6 Summary 45 3 Structural Model 47 3.1 Seismic Interpretation 47 3.1.1 Depth Conversion 52 3.1.2 Interpretation in Time Versus Depth 55 3.2 Fault Modelling 55 3.2.1 Fault Interpretation Process 59 3.2.2 Fault Naming 59 3.3 Horizon Modelling 62 3.4 Quality Control 62 3.5 Structural Uncertainty 63 3.6 Summary 64 4 StratigraphicModel 65 4.1 How Many Zones? 67 4.2 Multi-Zone Grid or Single-Zone Grids? 67 4.3 Well-to-Well Correlation 69 4.4 Geocellular Model 70 4.4.1 Capturing Heterogeneity 71 4.5 Geological Grid Design 75 4.5.1 Goals of Geological Grid Design 76 4.5.2 Orientation of the Geological Grid 77 4.5.3 The SmartModel Concept 79 4.6 Layering 79 4.6.1 Potential Dangers Using Conformable Grids 81 4.6.2 Erosion 83 4.7 Grid BuildingWorkflow 83 4.8 Quality Control 84 4.9 Uncertainty 85 4.10 Summary 85 5 Facies Model 87 5.1 FaciesModelling Basics 88 5.1.1 Defining the Facies Scheme 90 5.1.2 Upscaling of Log Data (BlockingWells) 95 5.1.3 Simplified Facies Description 98 5.1.4 Verification of the Zonation and the Facies Classes 98 5.1.5 Facies Proportions fromWell Data 99 5.2 FaciesModelling Methods 99 5.2.1 Pixel-Based Methods: Indicator and Gaussian Simulation 100 5.2.2 Object-Based Methods 104 5.2.3 Multi-Point StatisticalMethods 106 5.2.4 Conditioning to a Seismic Parameter 107 5.2.5 Conditioning to Dynamic Data 107 5.3 FaciesModellingWorkflows 107 5.4 Flow Zones 112 5.5 Uncertainty 112 5.6 Summary 114 6 Property Model 115 6.1 Rock and Fluid Properties 117 6.1.1 Porosity 117 6.1.2 Water Saturation 119 6.1.3 Permeability 119 6.1.4 Poro–Perm Relationship 120 6.1.5 Capillary Pressure 121 6.1.6 Wettability 122 6.2 Property Modelling 122 6.2.1 Property ModellingWorkflow 123 6.2.2 Data Preparation 124 6.2.3 Blocking or UpscalingWell Data 126 6.3 PropertyModellingMethods 127 6.3.1 DeterministicMethods 127 6.3.2 StatisticalMethods 129 6.3.3 Modelling Porosity 132 6.3.4 Modelling Permeability 134 6.3.5 ModellingWater Saturation 136 6.3.6 Modelling Net-to-Gross (NTG) 142 6.3.7 Incorporating Seismic Attributes 143 6.3.8 How Many Realizations? 145 6.3.9 Quality Control 146 6.4 Rock Typing 146 6.5 Carbonate Reservoir Evaluation 149 6.5.1 Rock Fabric Classification 150 6.5.2 Petrophysical Interpretation 152 6.6 Uncertainty 156 6.7 Summary 156 7 Volumetrics and Uncertainty 157 7.1 Work Flow Specification 161 7.1.1 Volumetrics Terminology 161 7.1.2 Products and Results 162 7.1.3 Necessary Data 162 7.2 Volumetric ModelWork Flow 163 7.2.1 Volumetrics with Stochastic Models 163 7.2.2 Volumetrics and Grid Resolution 164 7.2.3 Geo-model/Simulation Model Comparison 164 7.2.4 Reporting Volumetric Results 165 7.3 Resource and Reserves Estimation 165 7.3.1 Petroleum Resources Management System (PRMS) 166 7.4 UncertaintyModelling 171 7.4.1 Work Flow Specification 172 7.4.2 UncertaintyModelWorkflow 175 7.4.3 Ranking Realizations 177 7.4.4 Other UncertaintyMethods 178 7.4.5 Summary 179 8 Simulation and Upscaling 181 8.1 Simulation Grid Design 182 8.1.1 Grid DesignWork Flow 182 8.1.2 What is a Corner Point Grid? 183 8.1.3 Grid Design Goals 184 8.1.4 Grid Orientation Effects 186 8.1.5 Areal Grid Construction 187 8.1.6 Areal Representation of Faults 187 8.1.7 Aquifer Modelling 188 8.1.8 Local Grid Construction 188 8.1.9 Quality Control of Grids 189 8.2 Upscaling Property Models 190 8.2.1 Statistical Averages 191 8.2.2 Renormalization 193 8.2.3 Dynamic Upscaling 193 8.2.4 Comparison of UpscalingMethods 195 8.2.5 Local, Regional and Global Upscaling 196 8.2.6 Sampling for Upscaling 197 8.2.7 SamplingMethods Overview 197 8.2.8 Upscaling Porosity 199 8.2.9 Upscaling Permeability 199 8.2.10 Upscaling Net/Gross 200 8.2.11 Water SaturationModelling 201 8.2.12 Quality Control 202 8.3 Work Flow Specification 203 8.3.1 UpscalingWorkflow 203 8.4 Summary 204 9 Case Studies and Examples 205 9.1 Aeolian Environments 205 9.1.1 Building the Model 208 9.1.2 Remodelling 209 9.2 Alluvial Environments 210 9.2.1 Building the Model 218 9.3 Deltaic Environments 219 9.3.1 Building the Model 222 9.4 Shallow Marine Environment 226 9.4.1 Building the Model 226 9.5 Deepwater Environments 229 9.5.1 Building the Model 234 9.6 Carbonate Reservoirs 235 9.7 Fractured Reservoirs 244 9.8 UncertaintyModelling 248 9.8.1 Structural Model Uncertainty 249 9.8.2 FaciesModel Uncertainty 251 9.8.3 Petrophysical Uncertainty 254 9.9 Summary 255 Afterword 259 References 267 A Introduction to Reservoir Geostatistics 273 A.1 Basic Descriptive Statistics 275 A.2 Conditional Distributions 279 A.3 Spatial Continuity 280 A.3.1 Variogram Description 282 A.3.2 Zonal and Geometric Anisotropy 282 A.3.3 Variogram Estimation 284 A.4 Transforms 285 A.5 Lag Definition 286 A.6 Variogram Interpretation 287 A.6.1 Indicator Variograms 289 A.7 Kriging 290 A.7.1 Simple and Ordinary Kriging 290 A.7.2 Kriging with a Drift 291 A.7.3 Co-kriging 291 A.7.4 Indicator Kriging 293 A.8 Simulation 293 A.8.1 Sequential Gaussian Simulation (SGS) 295 A.8.2 Sequential Gaussian Simulation with External Drift 296 A.8.3 Sequential Indicator Simulation (SIS) 297 A.8.4 Sequential Co-located Co-simulation (SGCoSim) 297 A.8.5 Sequential Indicator Co-located Co-simulation 299 A.8.6 Truncated Gaussian Simulation (TGSim) 299 A.9 Object Modelling 302 A.10 Summary 305 Index 307

About the Author :
Steve Cannon is a geologist by profession, a petrophysicist by inclination and a reservoir modeller by design. He worked as a geologist and petrophysicist in all sectors of the oil and gas industry including government, oil companies, and the service sector. Cannon is a Past-President of the London Petrophysical Society.