Reservoir Model Design: A Practitioner's Guide

✍ Scribed by Philip Bentley, Mark Ringrose

• Publisher: Springer Nature
• Year: 2021
• Tongue: English
• Leaves: 333
• Edition: 2
• Category: Library

✦ Table of Contents

Preface
Prologue: Model Design
Successful Reservoir Modelling
Design in General
References
Acknowledgements
Contents
Chapter 1: Model Purpose
1.1 Modelling for Comfort?
1.2 Models for Visualisation Alone
1.3 Models for Volumes
1.4 Models as a Front End to Simulation
1.5 Models for Well Planning
1.6 Models for Seismic Modelling
1.7 Models for IOR/EOR
1.8 Models for Storage
1.9 The Fit-for-Purpose Model
References
Chapter 2: The Rock Model
2.1 The Rock Model
2.2 Model Concept
2.3 The Model Framework
2.3.1 Structural Data
2.3.2 Stratigraphic Data
2.3.2.1 Correlation
2.3.2.2 Use of Hierarchy
2.4 Model Elements
2.4.1 Reservoir Models Not Geological Models
2.4.2 Building Blocks
2.4.3 Model Element Types
2.4.3.1 Lithofacies Types
2.4.3.2 Genetic Elements
2.4.3.3 Stratigraphic Elements
2.4.3.4 Diagenetic Elements
2.4.3.5 Structural Elements
2.4.3.6 Exotic Elements
2.4.4 How Much Heterogeneity to Include? Flora´s Rule´ 2.5 Determinism and Probability 2.5.1 Balance Between Determinism and Probability 2.5.2 Different Generic Approaches 2.5.3 Forms of Deterministic Control 2.5.3.1 Faulting 2.5.3.2 Correlation and Layering 2.5.3.3 Choice of Algorithm 2.5.3.4 Boundary Conditions for Probabilistic Algorithms 2.5.3.5 Seismic Conditioning 2.6 Essential Geostatistics 2.6.1 Key Geostatistical Concepts 2.6.2 Intuitive Geostatistics 2.7 Algorithm Choice and Control 2.7.1 Object Modelling 2.7.2 Pixel-Based Modelling 2.7.3 Texture-Based Modelling 2.7.4 Algorithms Compared 2.7.5 Process-Based Modelling 2.7.6 The Importance of Deterministic Trends 2.7.6.1 Vertical Trends 2.7.6.2 Horizontal Trends 2.7.6.3 3D Probability Volumes 2.7.7 Alternative Rock Modelling Methods - A Comparison 2.8 Summary 2.8.1 Rock Model QC 2.8.2 Synopsis - Rock Modelling Guidelines References Chapter 3: The Property Model 3.1 Which Properties? 3.2 Understanding Permeability 3.2.1 Darcy´s Law 3.2.2 Upscaled Permeability 3.2.3 Permeability Variation in the Subsurface 3.2.4 Permeability Averages 3.2.5 Numerical Estimation of Block Permeability 3.2.6 Permeability in Fractures 3.3 Handling Statistical Data 3.3.1 Introduction 3.3.2 Variance and Uncertainty 3.3.3 The Normal Distribution and Its Transforms 3.3.4 Handling phi-k Distributions and Cross Plots 3.3.5 Hydraulic Flow Units 3.4 Modelling Property Distributions 3.4.1 Kriging 3.4.2 The Variogram 3.4.3 Gaussian Simulation 3.4.4 Bayesian Statistics 3.4.5 Property Modelling: Object-Based Workflow 3.4.6 Property Modelling: Seismic-Based Workflow 3.5 Use of Cut-Offs and N/G Ratios 3.5.1 Introduction 3.5.2 The Net-to-Gross Method 3.5.3 Total Property Modelling 3.6 Vertical Permeability and Barriers 3.6.1 Introduction to kv/kh 3.6.2 Modelling Thin Barriers 3.6.3 Modelling of Permeability Anisotropy 3.7 Saturation Modelling 3.7.1 Capillary Pressure 3.7.2 Saturation-Height Functions 3.7.3 Tilted Oil-Water Contacts 3.7.3.1 Kraka Field Example 3.8 Modelling Fracture Properties 3.8.1 Terminology and Type 3.8.2 Fault Zone Properties 3.8.3 Modelling Open Fracture Properties 3.8.4 Capturing the Effects of Stress on Fracture Properties 3.8.5 Summary - Fracture Properties 3.9 Summary References Chapter 4: Upscaling Flow Properties 4.1 Multi-scale Flow Modelling 4.2 Multi-phase Flow 4.2.1 Two-Phase Flow Equations 4.2.2 Two-Phase Steady-State Upscaling Methods 4.2.3 Heterogeneity and Fluid Forces 4.3 Multi-scale Reservoir Modelling Concepts 4.3.1 Geology and Scale 4.3.2 How Many Scales to Model and Upscale? 4.3.3 Which Scales to Focus On? (The REV) 4.3.4 Handling Variance as a Function of Scale 4.3.5 Construction of Geomodel and Simulator Grids 4.3.6 Which Heterogeneities Matter? 4.4 The Way Forward 4.4.1 Potential and Pitfalls 4.4.2 Pore-to-Field Workflow 4.4.3 Essentials of Multi-scale Reservoir Modelling References Chapter 5: Model-Based Uncertainty Handling 5.1 The Issue 5.1.1 Modelling for Comfort 5.1.2 Modelling for Discomfort - Quantifying Uncertainty and Exposing Risk 5.2 Differing Methodologies 5.2.1 Best Guess, orRationalist´ Approaches
5.2.2 Multiple Stochastic Approaches
5.2.3 Multiple Deterministic Approaches
5.3 Bias
5.3.1 The Limits of Rationalism
5.3.2 The Limits of Geostatistics
5.3.3 Cognitive Limits - Heuristics
5.4 Towards an Unbiased Methodology
5.4.1 The Uncertainty List
5.4.2 Scenario Trees
5.5 Post-processing the Ensemble
5.5.1 Scenarios
5.5.2 Exhaustive Deterministic Ensembles
5.5.3 Variance Mapping
5.5.4 Sampling Probabilistic Ensembles
5.5.5 Experimental Design and Sensitivity Analysis
5.5.6 Clustering
5.5.7 Updating Reservoir Uncertainty with New Information
5.5.8 Distinguishing and Illustrating Risk vs. Uncertainty
5.6 Summary
References
Chapter 6: Reservoir Model Types
6.1 Aeolian Reservoirs
6.1.1 Elements
6.1.2 Effective Properties
6.1.3 Stacking
6.1.4 Aeolian System Anisotropy
6.1.5 Laminae-Scale Effects
6.2 Fluvial Reservoirs
6.2.1 Fluvial Systems
6.2.2 Geometry
6.2.3 Connectivity and Percolation Theory
6.2.4 Hierarchy
6.3 Tidal Deltaic Sandstone Reservoirs
6.3.1 Tidal Characteristics
6.3.2 Handling Heterolithics
6.4 Shallow Marine Sandstone Reservoirs
6.4.1 Tanks of Sand?
6.4.2 Stacking and Laminations
6.4.3 Large-Scale Impact of Small-Scale Heterogeneities
6.5 Deep Marine Sandstone Reservoirs
6.5.1 Relative Confinement
6.5.2 Seismic Limits
6.5.3 Thin Beds
6.5.4 Small-Scale Heterogeneity in High Net-to-Gross Tanks´ 6.5.5 Summary 6.6 Carbonate Reservoirs 6.6.1 Depositional Architecture 6.6.2 Pore Fabric 6.6.3 Diagenesis 6.6.4 Fractures and Karst 6.6.5 Hierarchies of Scale - The Carbonate REV 6.6.6 Conclusion: Forward-Modelling or Inversion? 6.7 Fractured Reservoirs 6.7.1 Fracture Concepts 6.7.2 Low Density, Compartmentalised Fracture Systems (Fault-Dominated) 6.7.3 Low Density Fracture Systems, Open to Flow (Fault-Dominated) 6.7.4 High Density Fractured Reservoirs - Open to Flow (Joint-Dominated) 6.7.5 Forward-Modelling or Inversion in Fractured Reservoirs? 6.8 Fit-for-Purpose Recapitulation References Chapter 7: Models for Storage 7.1 Displacements of Different Fluids 7.2 Geological Storage of CO2 7.3 CO2 Storage Modelling Objectives 7.4 Understanding the CO2 Storage Process 7.5 The Influence of Geological Heterogeneity 7.6 Handling Pressure and Rock Deformation 7.7 Model Design Futures for the Energy Transition References Chapter 8: Modelling Workflows 8.1 The Detailed, Full-Field Model Default 8.2 Resource and Decision Models 8.3 Iterative Workflows - The Forth Bridge 8.4 Handling Dynamic Data 8.4.1 History-Matching 8.4.2 History-Comparing 8.5Truth Models´
References
Chapter 9: Epilogue - Modelling for the Energy Transition
9.1 Synopsis - The Story So Far
9.2 Use of Analogues and Data
9.3 Restoring Lost Heterogeneity
9.4 New Workflows
9.4.1 Surface-Based Models
9.4.2 Disposable Grids
9.5 Stepping Beyond the Solution - `Modelling for Understanding´
References
Nomenclature
Solutions
Exercise 2.1. Estimation of Variograms for an Outcrop Image
Exercise 3.1. Which Modelling Methods to Use?
Exercise 3.2. Additive Properties
Exercise 3.3. Dimensions of Permeability
Exercise 3.4. Comparing Model Distributions to Data
Exercise 3.5. Bayes and the Cookie Jar
Exercise 4.1. Permeability Upscaling for a Simple Layered Model
Exercise 4.2. Find the REV´s for Your Reservoir
Appendix A: A Template for Model Design
Index