Fundamentals and Practical Aspects of Gas Injection

Description

Preface Acknowledgements Contents 1 Introduction to Gas Injection 1.1 Introduction 1.2 Worldwide Distribution of Hydrocarbon Reservoirs 1.2.1 Conventional 1.2.2 Unconventional 1.3 Historical Evolution of Gas Injection 1.4 The Need for Gas Injection 1.5 Screening Criteria for Gas Injection 1.6 Sources of Gas for Gas Injection 1.7 Economics of Gas Injection 1.7.1 Pressure Maintenance 1.7.2 CCS 1.7.3 EOR 1.7.4 Underground Gas Storage References 2 PVT of Gas Injection 2.1 Introduction 2.2 Phase Diagram 2.2.1 Hydrocarbon Gas 2.2.2 Non-hydrocarbon Gas 2.2.3 Oil Samples 2.2.4 Mixtures of Oil and Gas 2.3 Pressure-Volume-Temperature (PVT) Experiments 2.3.1 Constant Composition Expansion 2.3.2 Differential Liberation 2.3.3 Constant Volume Depletion 2.3.4 Flash Separation 2.3.5 Swelling Test 2.4 PVT Calculation in Gas Injection Processes 2.4.1 Equation of State 2.4.2 Gas-Liquid Miscibility 2.4.3 Different States of Miscibility 2.4.4 Minimum Miscibility Pressure (MMP) 2.4.5 MMP Measurements 2.4.6 MMP Correlations 2.4.7 Ternary Diagram 2.5 The Impact of Gas Injection on Phase Behavior of Hydrocarbons 2.5.1 N2 Injection 2.5.2 CO2 Injection 2.5.3 CH4 Injection 2.6 Case Study of the Minimum Miscibility Pressure for Different Injected Gases 2.6.1 CH4/CO2 Solvent 2.6.2 CO2/N2 Solvent 2.6.3 CH4/N2 Solvent 2.6.4 CH4/C2H6 Solvent 2.6.5 C2H6/CO2 Solvent 2.6.6 C2H6/N2 Solvent 2.7 The Effect of Gas Injection on Asphaltene Precipitation 2.7.1 Pure N2 2.7.2 Pure CO2 2.7.3 Pure CH4 2.7.4 CH4 Dominant 2.7.5 CO2 Dominant 2.7.6 Comparison of Different Gases 2.8 Optimum Design of Gas Injection 2.9 PVT Challenges Associated with Gas Injection References 3 Basics of Oil and Gas Flow in Reservoirs 3.1 Introduction 3.2 Oil Flow 3.2.1 Basics of Oil Flow in Porous Media 3.2.2 Boundary Determination Between Darcy, Brinkman and Viscous Flow 3.2.3 Flowing Fluids and Diffusivity Equation in Porous Media 3.2.4 Relative Permeability 3.2.5 Flow Through Fractures and Fissures 3.2.6 Forces Acting on Fluid Flow in Oil Reservoirs 3.3 Gas Flow 3.3.1 The Diffusivity Equation for Gas Reservoirs 3.3.2 High Velocity Effects in Gas Flow 3.3.3 Flow Behavior of Gas Condensate Reservoirs 3.3.4 Gas Flow in Multilayer Reservoirs 3.3.5 Wettability Alteration Towards Gas Wetting of Reservoirs 3.3.6 Gas Flow in Unconventional Reservoirs Appendix 3.1: The Viscous Flow Equation in Cylindrical Coordinates Appendix 3.2: The Brinkman Equation in Cylindrical Coordinates Appendix 3.3: Linear Diffusivity Equation Solution Appendix 3.4: Solution of Non-linear Diffusivity Equation Appendix 3.5: The Solution of the Warren-Root Equation in the Different Boundary Condition Warren-Root Equations Constant Production Rate in Closed Outer Boundary Constant Production Rate in Constant Pressure Outer Boundary Constant Pressure Production in Closed Outer Boundary Constant Pressure Production in Constant Pressure Outer Boundary Warren-Root Analytical Solution References 4 Gas Injection for Underground Gas Storage (UGS) 4.1 Introduction 4.2 The Concept of UGS 4.3 History of UGS in the World 4.4 Candidate Reservoirs 4.5 Worldwide UGS Projects 4.6 Screening Criteria for UGS 4.7 UGS Key Aspects 4.7.1 Threshold Pressure 4.7.2 Well Testing 4.7.3 Rock Mechanics 4.8 Reservoir Fluid Phase Behavior in UGS 4.8.1 Injection Gas Versus Reservoir Fluid 4.8.2 Sour Gas Versus Sweet Gas 4.8.3 Condensate Re-vaporization During UGS 4.9 Reservoir Material Balance in UGS 4.9.1 Reserve Estimate in UGS 4.9.2 Drainage Radius in UGS 4.10 Well Pattern in UGS 4.11 Monitoring of UGS Projects 4.11.1 Surface Monitoring 4.11.2 Well Monitoring 4.11.3 Wellbore Integrity Monitoring 4.11.4 Micro-Seismic Monitoring 4.12 Numerical Simulation and Dynamic Modelling of UGS References 5 Gas Injection for Pressure Maintenance in Fractured Reservoirs 5.1 Introduction 5.2 The Concept of Pressure Maintenance 5.2.1 Gas Injection in Gas-Cap 5.2.2 Gas Recycling 5.2.3 Water Injection 5.3 History of Pressure Maintenance 5.4 Sources of Injected Gas 5.5 Active Mechanisms During Pressure Maintenance 5.5.1 Convection (Bulk Flow) 5.5.2 Molecular Diffusion 5.6 Worldwide Pressure Maintenance Projects 5.7 Reservoir Material Balance for Pressure Maintenance 5.7.1 Muskat’s Material Balance 5.7.2 Integral Material Balance Equations 5.7.3 Differential Material Balance Equation 5.8 Pressure Maintenance in Fractured Reservoirs 5.8.1 Block-To-Block Process 5.8.2 Gravity Drainage 5.8.3 Capillary Hold-up 5.8.4 Diffusion 5.8.5 Dispersion 5.8.6 Oil Recovery by Gas Injection in Naturally Fractured Reservoirs: Diffusion or Convection Dominated? 5.9 Well Design and Pattern in Pressure Maintenance 5.10 Simulation of Pressure Maintenance 5.10.1 Methods of Fractured Reservoirs Modelling 5.10.2 Simulation of Naturally Fractured Reservoirs by Finite Element Method 5.10.3 Compositional Numerical Simulation 5.11 Case Study of Pressure Maintenance 5.11.1 Geometry Description 5.11.2 Rock Properties 5.11.3 Fluid Properties 5.11.4 Model Description 5.11.5 Well Model 5.11.6 Analysis of Results Appendices Appendix A: Derivation of the Multiphase Flow Equations in Compositional Simulation Appendix B: Discretizing the Flow Equations Appendix C: Newton–Raphson Method References 6 Gas Recycling 6.1 Introduction 6.2 The Concept of Gas Recycling 6.3 Economics of Gas Recycling 6.4 Advantages and Disadvantages of Gas Recycling 6.5 History of Gas Recycling 6.6 Worldwide Gas Recycling Projects 6.7 Reservoir Material Balance Calculations for Gas Recycling 6.7.1 Material Balance for Gas Recycling in Oil Reservoir 6.7.2 Material Balance for Gas Recycling in Gas Condensate Reservoirs 6.8 Operation Design and Well Pattern in Gas Recycling 6.9 Gas Recycling in Fractured Reservoirs 6.9.1 Gravity Drainage 6.9.2 Block-To-Block Process 6.9.3 Capillary Hold-Up 6.9.4 Diffusion and Dispersion 6.10 Alternatives to Gas Recycling 6.11 Modelling the Gas Recycling into the Gas Condensate Reservoirs 6.11.1 Governing Equation 6.11.2 Mass Transfer During Re-vaporization of Condensate 6.12 Case Study: Simulation of Gas Recycling 6.12.1 PVT Modelling 6.12.2 Compositional Numerical Simulation 6.12.3 Optimization References 7 Design of Subsurface and Surface Facilities for Gas Injection 7.1 Introduction 7.2 Conceptual Design and General Layout 7.3 Design Considerations 7.4 Design Basis 7.5 Pipeline Design 7.6 Compressor Design 7.7 Intercooler Design 7.8 Separator Design 7.9 Well Design References 8 Water-Hydrocarbons System 8.1 Introduction 8.2 Water Content of Hydrocarbon Gases 8.2.1 Lean Sweet Natural Gas Water Content Correlation 8.2.2 Propane Water Content Charts 8.2.3 Ethane Water Content Charts 8.2.4 Acid Gases Water Content Charts 8.2.5 Sour Natural Gas Water Content Charts 8.3 Gas Solubility 8.3.1 Solubility of Hydrocarbons in Water 8.3.2 Solubility of Non-hydrocarbon Gases in Water 8.3.3 Calculation of Gas Solubility 8.3.4 Effect of Salt on the Gas Solubility in Water 8.4 Activity Models References 9 Challenges of Gas Injection 9.1 Introduction 9.2 Fluid-Fluid and Rock-Fluid Compatibility 9.3 Corrosion 9.3.1 CCS 9.3.2 Acid Gas Disposal 9.3.3 Flue Gas Injection 9.4 Gravity Override 9.5 Mobility Control 9.6 Cap Rock Integrity 9.7 Trapping 9.8 Health, Safety and Environment (HSE) of Gas Injection 9.8.1 CCS 9.8.2 EOR 9.8.3 Underground Gas Injection (UGS) References 10 Capillary Phase Trapping 10.1 Introduction 10.2 Capillary Trapping 10.2.1 Pore Structure 10.2.2 Initial Saturation and Trapping Curve 10.2.3 Wettability 10.2.4 Relative Permeability 10.2.5 Interfacial Tension 10.2.6 Capillary, Viscous and Gravitational Forces 10.3 Essential Dimensionless Groups in Phase Trapping 10.3.1 Capillary Number 10.3.2 Bond Number 10.3.3 Viscosity Ratio (Mobility) 10.4 Importance of Trapping 10.4.1 Oil Recovery 10.4.2 CO2 Storage 10.4.3 Condensate Recovery 10.5 Capillary Trapping Mechanisms 10.5.1 Snap-off 10.5.2 By-Passing 10.6 Mobilization of Trapped Phase 10.6.1 Gas Injection to Remove Trapped Phase 10.7 Capillary Trapping Models 10.7.1 Land Model (1968) 10.7.2 Aissaoui Model (1983) 10.7.3 Ma and Youngren Model (1994) 10.7.4 Jerauld Model (1997) 10.7.5 Kleppe et al. Model (1997) 10.7.6 Spiteri et al. Model (2008) 10.7.7 Iglauer et al. Model (2009) 10.7.8 Evaluation of Best Trapping Model 10.8 Capillary Trapping Laboratory Methods 10.8.1 Centrifuge Method 10.8.2 Unsteady State (USS) Method 10.8.3 Steady State (SS) Method 10.8.4 Porous Plate (PP) Method Appendix: Derivation of Velocity Ratio Expression References