Fundamentals of Gas Shale Reservoirs

Reza Rezaee is a Professor in the Department of Petroleum Engineering at Curtin University, Australia. He is the winner of Australian Gas innovation research 2012 award for introducing a new method to enhance natural gas production from tight gas reservoirs. He has published more than 120 peer-reviewed journal and conference papers and is the author of 3 books. His current research has been focused on integrated reservoir characterization, formation evaluation and petrophysics. He is a former “Research Fellow”, School of Geology and Geophysics, Oklahoma University.

• Contributors xvPreface xvii1 Gas Shale: Global Significance Distribution and Challenges 11.1 Introduction 11.2 Shale Gas Overview 11.2.1 Shale Gas Geology 21.2.2 Characteristics of a Producing Shale Gas Play 31.3 The Significance of Shale Gas 41.4 Global Shale Gas Resources 51.4.1 Sources of Information 51.4.2 Resource Estimation Methodologies 51.5 Global Resource Data 71.5.1 China 71.5.2 The United States 71.5.3 Mexico 71.5.4 Southern South America 71.5.5 South Africa 81.5.6 Australia 81.5.7 Canada 81.5.8 North Africa 81.5.9 Poland 91.5.10 France 91.5.11 Russia 91.5.12 Scandinavia 91.5.13 Middle East 91.5.14 India 91.5.15 Pakistan 101.5.16 Northwest Africa 101.5.17 Eastern Europe (Outside of Poland) 101.5.18 Germany and Surrounding Nations 101.5.19 The United Kingdom 101.5.20 Northern South America 111.5.21 Turkey 111.6 Data Assessment 111.6.1 Distribution 111.6.2 Basin Type 111.6.3 Depositional Environment 121.6.4 TOC Content 121.6.5 Clay Content 131.7 Industry Challenges 131.7.1 Environmental Challenges 131.7.2 Commercial/Economic 141.8 Discussion 141.9 Conclusions 15Appendix A.1 Global Shale Gas Resource Data 162 Organic Matter]Rich Shale Depositional Environments 212.1 Introduction 212.2 Processes Behind the Deposition of Organic Matter]Rich Shale 232.2.1 Processes Behind the Transport and Deposition of Mud 232.2.2 Production Destruction and Dilution: The Many Roads to Black Shale 232.3 Stratigraphic Distribution of Organic Matter]Rich Shales 252.4 Geographic Distribution of Organic Matter]Rich Shales 272.4.1 Background 272.4.2 Controls on the Geographic Distribution of Black Shales 302.5 Organic Matter]Rich Shale Depositional Environments 342.5.1 Continental Depositional Environments 342.5.2 Paralic Depositional Environments 362.5.3 Shallow Marine Depositional Environments 372.5.4 Deep Marine Depositional Environments 382.6 Conclusion 393 Geochemical Assessment of Unconventional Shale Gas Resource Systems 473.1 Introduction 473.2 Objective and Background 493.3 Kerogen Quantity and Quality 493.4 Sample Type and Quality 513.5 Kerogen Type and Compositional Yields 523.6 Thermal Maturity 543.7 Organoporosity Development 553.8 Gas Contents 573.9 Expulsion–Retention of Petroleum 573.10 Secondary (Petroleum) Cracking 583.11 Upper Maturity Limit for Shale Gas 583.12 Gas Composition and Carbon Isotopes 593.13 Additional Geochemical Analyses for Shale Gas Resource System Evaluation 613.14 Oil and Condensate with Shale Gas 633.15 Major Shale Gas Resource Systems 643.16 Conclusions 654 Sequence Stratigraphy of Unconventional Resource Shales 714.1 Introduction 714.2 General Sequence Stratigraphic Model for Unconventional Resource Shales 714.3 Ages of Sea]Level Cycles 724.4 Water Depth of Mud Transport and Deposition 734.5 Criteria to Identify Sequences and Systems Tracts 744.6 Paleozoic Resource Shale Examples 744.6.1 Barnett Shale (Devonian) 744.6.2 Woodford Shale (Late Devonian–Early Mississippian) 744.6.3 Marcellus Shale (Devonian) 784.6.4 New Albany Shale (Upper Devonian–Lower Mississippian) 784.7 Mesozoic Resource Shale Examples 804.7.1 Montney Formation (Early Triassic) 804.7.2 Haynesville/Bossier Shales (Late Jurassic) 804.7.3 Eagle Ford Formation (Cretaceous) 804.7.4 LaLuna Formation (Upper Cretaceous) 824.8 Cenozoic Resource Shale Example 834.9 Conclusions 844.10 Applications 845 Pore Geometry in Gas Shale Reservoirs 895.1 Introduction 895.1.1 Gas Shales and Their Challenges 895.1.2 Pore Size Classification 905.2 Samples Characteristics 905.2.1 Sample Collection 905.2.2 Mineral Composition 905.3 Experimental Methodology 915.3.1 Capillary Pressure Profile 915.3.2 Nitrogen Adsorption (N2) 925.3.3 Low]Field NMR 925.3.4 Image Acquisition and Analysis 935.4 Advantages and Disadvantages of Experimental PSD Methods 955.5 Permeability Measurement 955.6 Results 965.6.1 Pore Size Distribution from MICP Experiments 965.6.2 Pore Size Distribution from Nitrogen Adsorption Experiments 985.6.3 NMR T2 Relaxation Time 985.6.4 Scanning Electron Microscopy 1005.6.5 Focused Ion Beam/Scanning Electron Microscopy 1005.6.6 Capillary Pressure and Permeability 1025.7 Discussion 1035.7.1 Porosity and PSD Comparisons 1035.7.2 Interchanging MICP with NMR Data 1035.7.3 Pore]Body to Pore]Throat Size Ratio: Pore Geometry Complexity 1075.7.4 Pore Throat Size and Permeability 1075.7.5 Mineralogy 1085.8 Conclusions 112Appendix 5.A XRD Results 1146 Petrophysical Evaluation of Gas Shale Reservoirs 1176.1 Introduction 1176.2 Key Properties for Gas Shale Evaluation 1176.2.1 Pore System Characteristics 1176.2.2 Organic Matter Characteristics 1186.2.3 Permeability 1186.2.4 Gas Storage Capacity 1196.2.5 Shale Composition 1206.2.6 Geomechanical Properties 1206.3 Petrophysical Measurements of Gas Shale Reservoirs 1216.3.1 Pore Structure Evaluation Techniques 1216.3.2 Fluid Saturation Measurement 1226.3.3 Permeability Measurement 1236.3.4 Adsorbed Gas Measurement 1246.4 Well Log Analysis of Gas Shale Reservoirs 1256.4.1 Well Log Signatures of Gas Shale Formations 1256.4.2 Well Log Interpretation of Gas Shale Formations 1287 Pore Pressure Prediction for Shale Formations Using well Log Data 1397.1 Introduction 1397.1.1 Normal Pressure 1397.1.2 Overpressure 1397.2 Overpressure-Generating Mechanisms 1407.2.1 Loading Mechanisms 1417.2.2 Unloading Mechanisms (Fluid Expansion) 1427.2.3 World Examples of Overpressures 1437.2.4 Overpressure Indicators from Drilling Data 1447.2.5 Identification of Shale Intervals 1447.3 Overpressure Estimation Methods 1467.3.1 Overview of the Compaction Theory 1467.3.2 Eaton’s Method 1477.3.3 Effective Stress Method 1497.3.4 Bowers’s Method 1507.4 The Role of Tectonic Activities on Pore Pressure In Shales 1517.4.1 Geology of the Study Area 1517.4.2 Stress Field in the Perth Basin 1527.4.3 Pore Pressure in Tectonically Active Regions (Uplifted Areas) 1547.4.4 Pore Pressure in Tectonically Stable Regions 1547.4.5 Origins of Overpressure in Kockatea Shale 1567.5 Discussion 1607.5.1 Significance of Pore Pressure Study 1637.5.2 Overpressure Detection and Estimation 1637.5.3 Pore Pressure and Compressional Tectonics 1637.5.4 Overpressure-Generating Mechanisms 1647.5.5 Overpressure Results Verifications 1647.6 Conclusions 1658 Geomechanics of Gas Shales 1698.1 Introduction 1698.2 Mechanical Properties of Gas Shale Reservoirs 1708.2.1 Gas Shale Reservoir Properties under Triaxial Loading 1708.2.2 True]Triaxial Tests 1718.2.3 Gas Shale Reservoir Properties under Ultrasonic Tests 1728.2.4 Nanoindentation Tests on Gas Shale Plays 1738.2.5 Scratch Tests 1748.3 Anisotropy 1758.3.1 Anisotropy in Gas Shale Reservoirs 1758.4 Wellbore Instability in Gas Shale Reservoirs 1768.4.1 Structurally Controlled Instability 1778.4.2 Instability Due to Directional Dependency of Geomechanical Parameters 1788.4.3 Time]Dependent Instability 1849 Rock Physics Analysis of Shale Reservoirs 1919.1 Introduction 1919.2 Laboratory Measurements on Shales: Available Datasets 1929.3 Organic Matter Effects on Elastic Properties 1929.4 Partial Saturation Effects 1959.5 Maturity Effects 1979.6 Seismic Response of Orss 2019.7 Conclusions 20310 Passive Seismic Methods for Unconventional Resource Development 20710.1 Introduction 20710.2 Geomechanics and Natural Fracture Basics for Application to Hydraulic Fracturing 20910.2.1 Basics of Earth Stress and Strain 20910.2.2 Natural Fracture Basics and Interaction with Hydraulic Fractures 21110.3 Seismic Phenomena 21310.3.1 MEQs and Their Magnitudes 21310.3.2 Earthquake Focal Mechanisms 21310.3.3 Other Types of Seismic Activity Produced by Hydraulic Fracturing 21610.4 Microseismic Downhole Monitoring 21610.4.1 Downhole Monitoring Methodology 21610.4.2 Advantages and Disadvantages of Downhole Monitoring 22010.5 Monitoring Passive Seismic Emissions with Surface and Shallow Buried Arrays 22210.5.1 Recording 22210.5.2 Seismic Emission Tomography 22310.5.3 MEQ Methods 22910.5.4 Imaging Cumulative Seismic Activity 23010.5.5 Direct Imaging of Fracture Networks 23210.5.6 Comparison of Downhole Hypocenters and Fracture Images 23210.5.7 Summary 23310.6 Integrating Interpreting and Using Passive Seismic Data 23510.6.1 General Considerations 23510.6.2 Interpreting Reservoir Stress from Focal Mechanisms 23610.6.3 Fracture Width Height SRV and Tributary Drainage Volume 24010.6.4 Using Passive Seismic Results for Frac Well]Test and Reservoir Simulation 24010.7 Conclusions 24111 Gas Transport Processes in Shale 24511.1 Introduction 24511.2 Detection of Nanopores in Shale Samples 24711.3 Gas Flow in Micropores and Nanopores 24811.4 Gas Flow in a Network of Pores in Shale 25111.5 Gas Sorption in Shale 25211.6 Diffusion in Bulk Kerogen 25311.7 Measurement of Gas Molecular Diffusion into Kerogen 25511.8 Pulse]Decay Permeability Measurement Test 25611.8.1 Pulse]Decay Pressure Analysis 25711.8.2 Estimation of Permeability Parameters with the Pulse]Decay Experiment 25911.9 Crushed Sample Test 26011.9.1 Porosity Measurement 26011.9.2 Crushed Sample Pressure Analysis for Permeability Measurement 26111.9.3 Crushed Sample Permeability Estimation with Early]Time Pressure Data 26211.9.4 Crushed Sample Permeability Estimation with Late]Time Pressure Data 26211.10 Canister Desorption Test 26211.10.1 Permeability Estimation with Early Time Cumulative Desorbed Gas Data 26311.10.2 Permeability Estimation with Late]Time Cumulative Desorbed Gas Data 26412 A Review of the Critical Issues Surrounding the Simulation of Transport and Storage in Shale Reservoirs 26712.1 Introduction 26712.2 Microgeometry of Organic]Rich Shale Reservoirs 26812.3 Gas Storage Mechanisms 26912.4 Fluid Transport 27012.5 Capillary Pressure Relaxation to Equilibrium State and Deposition of Stimulation Water 27312.6 Characterization of Fluid Behavior and Equations of State Valid for Nanoporous Media 27412.6.1 Viscosity Corrections 27612.6.2 Corrections for Interfacial Tension 27712.7 Upscaling Heterogeneous Shale]Gas Reservoirs into Large Homogenized Simulation Grid Blocks 27712.7.1 Upscaling Fine Continuum Model of Shale to Lumped]Parameter Leaky Tank Model of Shale 27812.7.2 Upscaling Finely Detailed Continuum Model of Shale to Coarse Continuum Model of Shale 27912.8 Final Remarks 28013 Performance Analysis of Unconventional Shale Reservoirs 28313.1 Introduction 28313.2 Shale Reservoir Production 28313.3 Flow Rate Decline Analysis 28413.3.1 Decline Curve Analysis in Unconventional Reservoirs 28513.3.2 Flow Rate Transient Analysis (RTA) and its Relation to Rate Decline Analysis 28613.3.3 Field Applications 28713.4 Flow Rate and Pressure Transient Analysis in Unconventional Reservoirs 28813.4.1 Bilinear Flow Regime in Multistage Hydraulic Fracturing 28813.4.2 Linear Flow Analysis for Reservoir Permeability 28913.4.3 Field Applications 29013.4.4 Type-Curve Matching 29013.5 Reservoir Modeling and Simulation 29213.5.1 History Matching and Forecasting 29213.5.2 Dual-Porosity Single-Phase Modeling 29313.5.3 Dual-Porosity Multicomponent Gas Modeling 29413.6 Specialty Short-Term Tests 29513.6.1 Mini-DST 29513.6.2 Mini-Frac Test 29613.7 Enhanced Oil Recovery 29713.8 Conclusion 29814 Resource Estimation for Shale Gas Reservoirs 30114.1 Introduction 30114.1.1 Unique Properties of Shale 30114.1.2 Petroleum Resources Management System (PRMS) 30114.1.3 Energy Information Administration’s Classification System 30114.1.4 Reserves Estimate Methodology for Unconventional Gas Reservoirs 30214.1.5 Monte Carlo Probabilistic Approach 30214.1.6 Analytical Models 30314.1.7 Economic Analysis 30314.1.8 Region]Level World Shale Gas Resource Assessments 30414.1.9 Shale Gas OGIP Assessment in North America 30514.1.10 Recent Shale Gas Production and Activity Trends 30614.1.11 Drilling Stimulation and Completion Methods in Shale Gas Reservoirs 30814.2 Methodology 30914.3 Resource Evaluation of Shale Gas Plays 31014.3.1 Reservoir Model 31014.3.2 Well Spacing Determination 31014.3.3 Reservoir Parameters Sensitivity Analysis 31114.3.4 Reservoir Parameters 31214.3.5 Model Verification 31214.3.6 Resource Assessment 31314.3.7 Reserve Evaluation 31814.4 Discussion 32015 Molecular Simulation of Gas Adsorption in Minerals and Coal: Implications for Gas Occurrence in Shale Gas Reservoirs 32515.1 Introduction 32515.1.1 Molecular Dynamics Simulation 32515.1.2 Major Challenges in Shale Gas Research 32615.1.3 MS of Gas Adsorption 32615.1.4 Methodology and Workflow of Molecular Simulation 32715.1.5 Simulation Algorithms and Software 32715.2 MS of Gas Adsorption on Minerals 32715.2.1 MD Simulation of Gas Adsorption on Quartz 32815.2.2 Molecular Dynamic Simulation of Gas Adsorption on Wyoming]Type Montmorillonite 33015.2.3 MD Simulation of Gas Adsorption on Zeolite 33215.2.4 MD Simulation of Gas Adsorption on Coal 33415.3 Conclusions 33716 Wettability of Gas Shale Reservoirs 34116.1 Introduction 34116.2 Wettability 34116.3 Imbibition in Gas Shales 34216.4 Factors Influencing Water Imbibition in Shales 34316.4.1 Sample Expansion 34316.4.2 Depositional Lamination 34616.4.3 Chemical Osmosis 34616.4.4 Water Film and Salt Crystals 34816.4.5 Water Adsorption (Clay Swelling) 34816.4.6 Connectivity of Hydrophobic and Hydrophilic Pore Networks 34916.4.7 Effect of Polymer and Surfactant 35116.5 Quantitative Interpretation of Imbibition Data 35216.5.1 Scaling Imbibition Data 35216.5.2 Modeling Imbibition Data 35216.6 Estimation of Brine Imbibition at the Field Scale 35416.7 Initial Water Saturation in Gas Shales 35616.8 Conclusions 35617 Gas Shale Challenges Over The Asset Life Cycle 36117.1 Introduction 36117.2 The Asset Life Cycle 36117.2.1 Exploration Phase Objectives—Recommended Practices 36117.2.2 Appraisal Phase Objectives—Recommended Practices 36217.2.3 Development Phase Objectives—Recommended Practices 36217.2.4 Production Phase Objectives—Recommended Practices 36217.2.5 Rejuvenation Phase Objectives—Recommended Practices 36217.3 Exploration Phase Discussion 36217.3.1 Screening Study—Current Practice 36217.3.2 Screening Study Recommended Practices 36317.3.3 Reservoir Characterization—Current Practice 36317.3.4 Reservoir Characterization—Recommended Practices 36317.3.5 Determining Initial Economic Value and Reservoir Potential 36517.4 Appraisal Phase Discussion 36517.4.1 Drill Appraisal Wells—Current Practice 36517.4.2 Drill Appraisal Wells—Recommended Practices 36517.4.3 Build Reservoir Models for Simulation—Current Practice 36517.4.4 Build Reservoir Models for Simulation—Recommended Practices 36517.4.5 Generate a Field Development Plan—Current Practice 36617.4.6 Generate a Field Development Plan—Recommended Practices 36617.4.7 Validate Economics of the Play or Pilot Project 36617.5 Development Phase Discussion 36717.5.1 Implement the Field Development Plan 36717.5.2 Surface Facilities 36717.5.3 Design Wells and Optimize Drilling Costs—Current Practice 36717.5.4 Design Wells and Optimize Drilling Costs—Recommended Practice 36817.5.5 Refine and Optimize Hydraulic Fracturing and Wellbore Completion Design—Current Practices (Characterize the Lateral) 36917.5.6 Current Hydraulic Fracturing Practices 36917.5.7 Hydraulic Fracturing—Recommended Practices 37017.5.8 Characterize the Lateral 37217.5.9 Current Wellbore Completion Practice 37317.5.10 Wellbore Completion—Recommended Practices 37317.5.11 Drilling Considerations for Completion Methods 37517.5.12 Fracturing Considerations for Completion Method 37517.6 Production Phase Discussion 37517.6.1 Monitor and Optimize Producing Rates—Current Practice 37517.6.2 Monitor and Optimize Producing Rates—Recommended Practices 37517.6.3 Manage the Water Cycle—Recommended Practices 37617.6.4 Preventing Corrosion Scaling and Bacterial Contamination in Wells and Facilities 37617.6.5 Protecting the Environment 37617.7 Rejuvenation Phase Discussion 37617.8 Conclusions—Recommended Practices 37718 Gas Shale Environmental Issues and Challenges 38118.1 Overview 38118.2 Water Use 38118.3 The Disposal and Reuse of Fracking Wastewater 38218.4 Groundwater Contamination 38418.5 Methane Emissions 38618.6 Other Air Emissions 38718.7 Social Impacts on Shale Gas Communities 38818.8 Induced Seismicity: Wastewater Injection and Earthquakes 38818.9 Regulatory Developments 38918.10 Disclosure of Fracking Chemicals 38918.11 At the Federal Government Level 39018.12 Conclusion 391Index 397

“Comprehensive and up-to-date, Fundamentals of Gas Shale Reservoirs is an essential reference for anyone interested in gas shale reservoirs. It is also a must have text for students, of any discipline, studying non-conventional oil and gas resources and it is bound to become the 'gold standard' textbook in this field. In addition, this book is available in both print and e-book edition, making it easy to choose the format that best suits your needs.”  (Tundraco, 1 October 2015)