A Concise Guide to Geopressure: Origin, Prediction, and Applications

Description

Geopressure drives fluid flow and is important for hydrocarbon exploration, carbon sequestration, and designing safe and economical wells. This concise guide explores the origins of geopressure and presents a step-by-step approach to characterizing and predicting pressure and least principal stress in the subsurface. The book emphasizes how geology, and particularly the role of flow along permeable layers, drives the development and distribution of subsurface pressure and stress. Case studies, such as the Deepwater Horizon blowout, and laboratory experiments, are used throughout to demonstrate methods and applications. It succinctly discusses the role of elastoplastic behaviour, the full stress tensor, and diagenesis in pore pressure generation, and it presents workflows to predict pressure, stress, and hydrocarbon entrapment. It is an essential guide for academics and professional geoscientists and petroleum engineers interested in predicting pressure and stress, and understanding the role of geopressure in geological processes, well design, hydrocarbon entrapment, and carbon sequestration. Front matter Copyright Contents Acknowledgments Nomenclature 1 Introduction 1.1 The Deepwater Horizon Blowout 1.2 Audience and Application 1.3 The Discipline of Pore Pressure Analysis 1.4 Nomenclature 1.5 Summary 2 Reservoir Pore Pressure 2.1 Introduction 2.2 Pore Pressure 2.3 Vertical Stress and Vertical Effective Stress 2.4 Overpressure, and Pressure Gradient Plots 2.5 Example: The Bullwinkle J3 Sand 2.6 Capillary Pressure 2.6.1 Surface Tension 2.6.2 Capillary Pressure 2.6.3 Contact Angle (θ) 2.6.4 Capillary Rise 2.6.5 Interpreting Mercury Injection Capillary Pressure (MICP) Curves 2.7 Capillary/Gravity Equilibrium 2.7.1 Two Phase Capillary/Gravity Equilibrium 2.7.2 Three Phase Capillary/Gravity Equilibrium 2.8 Summary 3 Mudrock Material Behavior 3.1 Introduction 3.2 Mudrock Material Behavior 3.2.1 Compaction 3.2.2 Elastoplastic Behavior of Mudrocks 3.2.3 Horizontal Stresses During Uniaxial Normal Compression 3.2.4 Strength Measurements and Stress-Induced Pressures 3.2.5 Viscoplastic Behavior (Creep) 3.3 Stress State 3.3.1 Representation of Stress State 3.3.2 Stress State in the Earth 3.4 Generalized Mudrock Compaction Model 3.4.1 Full Effective Stress Compaction Model 3.4.2 Compaction Curves for Characteristic Stress States 3.5 Summary 4 The Origins of Geopressure 4.1 Introduction 4.2 Pore Pressure Generation and Dissipation under Vertical Loading 4.2.1 Effective Stress 4.2.2 Undrained Loading 4.2.3 Drained Compression 4.2.4 Consolidation 4.2.5 Pore Pressure Dissipation 4.2.6 Hydromechanical Properties 4.3 Sedimentation and Overpressure 4.3.1 Overpressure During Sedimentation 4.3.2 Numerical Uniaxial Basin Models 4.3.2.1 Overpressure During Constant Sedimentation 4.3.2.2 Pressure Retention Depth and Unloading 4.3.2.3 The Relative Role of Sedimentation, Thermal Expansion, and Smectite-Illite Diagenesis in Overpressure Generation 4.3.2.4 Stratigraphic Evolution and Pore Pressure Profiles 4.4 Pore Pressure in Complex Stress States 4.4.1 Hydromechanical Models 4.4.2 The Role of Mean- and Shear-Induced Pore Pressure 4.4.3 Full Effective Stress Hydromechanical Model Examples 4.4.3.1 Pore Pressure and Stress around an Evolving Salt Diapir 4.4.3.2 Pore Pressure and Stress in an Evolving Accretionary Prism 4.5 Viscous Compaction 4.6 Summary 5 Pore Pressure Prediction in Mudrocks 5.1 Introduction 5.2 Application to the Eugene Island 330 Oil Field and the Pathfinder Well 5.2.1 Observations in the Pathfinder Well 5.2.2 Determination of Normal Compaction Trend 5.2.3 Pore Pressure Prediction in the EI-330 A20 ST2 Well 5.3 Details of Pore Pressure Prediction 5.3.1 Picking Lithologies for Pore Pressure Prediction 5.3.2 Calibrating Compaction Behavior in Overpressure 5.4 Other Normal Compaction Trend Methods 5.4.1 Other Porosity-Effective Stress Methods 5.4.2 Velocity-Effective Stress Methods 5.4.2.1 Eaton Approach 5.4.2.2 Bowers Velocity-Effective Stress Approach 5.4.3 Resistivity-Based Methods 5.5 Comparison of Pressure Prediction Models 5.6 Summary 6 Pore Pressure Prediction: Unloading, Diagenesis, and Non-Uniaxial Strain 6.1 Introduction 6.2 Pore Pressure Prediction in the Presence of Unloading 6.2.1 Geotechnical Model 6.2.2 Bowers Unloading Model 6.2.3 Determination of the Preconsolidation Stress 6.3 Pore Pressure Prediction with Smectite-Illite Transformation 6.3.1 Smectite-Illite Diagenesis 6.3.2 Pore Pressure Prediction at EI-330 A20 ST2 Well 6.4 Pore Pressure Prediction in Different Tectonic Environments 6.4.1 Introduction 6.4.2 Pressure Prediction Examples with the Full Stress Tensor 6.5 Summary 7 Pressure and Stress from Seismic Velocity 7.1 Introduction 7.2 Seismic Velocity 7.2.1 Dix Velocity Analysis 7.2.2 ‘Verticalizing’ the Data: Calibration and Velocity Anisotropy 7.2.3 Lateral Velocity Variation 7.3 Reflection Tomography 7.4 Seismic-Based Pore Pressure Prediction 7.4.1 Vertical Effective Stress Method 7.4.1.1 One-Dimensional Example 7.4.1.2 Two-Dimensional Example 7.4.2 Full Effective Stress Method 7.5 Summary 8 Overburden Stress, Least Principal Stress, and Fracture Initiation Pressure 8.1 Introduction 8.2 Characterization of Overburden Stress 8.2.1 Overburden in the Shallow Section 8.2.2 Overburden Interpreted from Logs Recorded in Oil versus Water-Based Muds 8.2.3 The Effect of Salt and Bathymetry on Overburden 8.2.4 Overburden Stress: Summary 8.3 Least Principal Stress and Fracture Initiation Pressure 8.3.1 Characterization of Formation Pressure Integrity Tests 8.3.2 The Interpretation of Pressure Integrity Tests 8.3.3 The Interpretation of Lost Circulation Events 8.3.4 Least Principal Stress and Fracture Initiation Pressure Models 8.3.4.1 Least Principal Stress 8.3.4.2 Modeling the Fracture Initiation Pressure 8.3.5 Example: Least Principal Stress at the Macondo Well 8.3.6 Summary: Least Principal Stress and Fracture Initiation Pressure 8.4 Summary 9 Trap Integrity 9.1 Introduction 9.2 Capillary (Membrane) Seal 9.2.1 Overview 9.2.2 Example 9.2.3 Controls on Displacement Behavior 9.2.4 Impact of Water Phase Pressure and Seal Heterogeneity on Trapping 9.3 Mechanical Seal 9.3.1 Seal Limited by Hydraulic Fracturing 9.3.2 Shear Failure 9.3.3 Demonstration of Mechanical Seal Capacity 9.3.4 Mechanical Seal Examples 9.4 Summary 10 Flow Focusing and Centroid Prediction 10.1 Introduction 10.2 Flow Focusing 10.2.1 Physical Example 10.2.2 Flow Focusing Model 10.3 Field Examples 10.4 Predicting the Centroid Depth 10.4.1 Predicting Centroid Depth from Reservoir Geometry 10.4.2 Dependence of Centroid Depth on Mudrock Permeability 10.4.3 Centroid Prediction as Function of Both Permeability and Reservoir Geometry 10.5 The Impact of Reservoir Hydrocarbons on Centroid Position 10.6 Reservoir Compaction and the Centroid Model 10.7 Summary 11 Flow Focusing, Fluid Expulsion, and the Protected Trap 11.1 Introduction 11.2 The Popeye-Genesis Protected Trap 11.2.1 The Popeye Basin: Gulf of Mexico 11.2.2 The Protected Trap Concept 11.3 Shallow Water Flow and Submarine Landslides 11.4 Outcrop Examples 11.5 Summary References Index