Geothermal Energy Systems

Research activities of Ernst Huenges aim at providing an environmentally benign and sustainable geothermal energy and subsurface storage of heat and cold. In his focus the supply of geothermal energy should become site-independent in the long-term and tailored according to demand and thus supplementing, at the same time, other renewable energy sources. This requires interdisciplinary approaches and synergies seen in connection with a series of developing fields of research involving the editor’s experimental expertise on processes in deep reservoirs.

"It can be said that this book achieves his goal to be a reference of great value to scientists and decision-makers in research and politics, as well as those giving courses in petroleum engineering, for example. It provides a good overview on the state of the art of all the aspects, which need to be considered, when installing an Enhanced Geothermal Systems Plant. It should not be missed in the bookshelf's of people dealing with geothermal use." (Corrosion News, January 2011)

• Preface xvList of Contributors xix1 Reservoir Definition 1Patrick Ledru and Laurent Guillou Frottier1.1 Expressions of Earth’s Heat Sources 11.1.1 Introduction to Earth’s Heat and Geothermics 11.1.2 Cooling of the Core, Radiogenic Heat Production, and Mantle Cooling 21.1.3 Mantle Convection and Heat Loss beneath the Lithosphere 41.1.3.1 Mantle Heat Flow Variations 41.1.3.2 Subcontinental Thermal Boundary Condition 51.1.4 Fourier’ Law and Crustal Geotherms 61.1.5 Two-dimensional Effects of Crustal Heterogeneities on Temperature Profiles 81.1.5.1 Steady-state Heat Refraction 81.1.5.2 Transient Effects 101.1.5.3 Role of Anisotropy of Thermal Conductivity 101.1.6 Fluid Circulation and Associated Thermal Anomalies 121.1.7 Summary 131.2 Heat Flow and Deep Temperatures in Europe 131.2.1 Far-field Conditions 141.2.2 Thermal Conductivity, Temperature Gradient, and Heat Flow Density in Europe 171.2.3 Calculating Extrapolated Temperature at Depth 181.2.4 Summary 201.3 Conceptual Models of Geothermal Reservoirs 211.3.1 The Geology of Potential Heat Sources 221.3.2 Porosity, Permeability, and Fluid Flow in Relation to the Stress Field 271.3.3 Summary 30References 322 Exploration Methods 37David Bruhn, Adele Manzella, François Vuataz, James Faulds, Inga Moeck, and Kemal Erbas2.1 Introduction 372.2 Geological Characterization 392.3 Relevance of the Stress Field for EGS 442.4 Geophysics 522.4.1 Electrical Methods (DC, EM, MT) 532.4.1.1 Direct Current (DC) Methods 542.4.1.2 Electromagnetic Methods 552.4.1.3 The Magnetotelluric Method 552.4.1.4 Active Electromagnetic Methods 632.4.2 Seismic Methods 662.4.2.1 Active Seismic Sources 672.4.2.2 Seismic Anisotropy and Fractures 712.4.2.3 Passive Seismic Methods 732.4.3 Potential Methods 762.4.3.1 Gravity 762.4.3.2 Geomagnetics and Airborne Magnetic 782.4.4 Data Integration 802.4.4.1 Joint Inversion Procedures 812.5 Geochemistry 812.5.1 Introduction 812.5.2 Fluids and Minerals as Indicators of Deep Circulation and Reservoirs 832.5.3 Mud and Fluid Logging while Drilling 852.5.4 Hydrothermal Reactions 862.5.4.1 Boiling and Mixing 882.5.5 Chemical Characteristics of Fluids 912.5.5.1 Sodium–Chloride Waters 922.5.5.2 Acid–Sulfate Waters 922.5.5.3 Sodium–Bicarbonate Waters 932.5.5.4 Acid Chloride–Sulfate Waters 932.5.6 Isotopic Characteristics of Fluids 942.5.7 Estimation of Reservoir Temperature 972.5.7.1 Geothermometric Methods for Geothermal Waters 982.5.7.2 Silica Geothermometer 982.5.7.3 Ionic Solutes Geothermometers 992.5.7.4 Gas (Steam) Geothermometers 1002.5.7.5 Isotope Geothermometers 1002.5.8 Forecast of Corrosion and Scaling Processes 100References 103Further Reading 1113 Drilling into Geothermal Reservoirs 113Axel Sperber, Inga Moeck, and Wulf Brandt3.1 Introduction 1133.1.1 Geothermal Environments and General Tasks 1143.2 Drilling Equipment and Techniques 1153.2.1 Rigs and Their Basic Concepts 1153.2.1.1 Hoisting System 1153.2.1.2 Top Drive or Rotary Table 1153.2.1.3 Mud Pumps 1163.2.1.4 Solids Control Equipment 1183.2.1.5 Blowout Preventer (BOP) 1183.2.2 Drillstring 1183.2.2.1 Bottomhole Assembly 1183.2.2.2 Drillpipe 1213.2.3 Directional Drilling 1223.2.3.1 Downhole Motor (DHM) 1223.2.3.2 Rotary Steerable Systems (RSS) 1223.2.3.3 Downhole Measuring System (MWD) with Signal Transmission Unit (Pulser) 1233.2.3.4 Surface Receiver to Receive and Decode the Pulser Signals 1233.2.3.5 Special Computer Program to Evaluate Where the Bottom of the Hole Is at Survey Depth 1233.2.4 Coring 1253.3 Drilling Mud 1253.3.1 Mud Types 1263.3.1.1 Water-based Mud 1263.3.1.2 Oil-based Mud 1263.3.1.3 Foams 1263.3.1.4 Air 1263.3.2 The Importance of Mud Technology in Certain Geological Environments 1273.3.2.1 Drilling through Plastic/Creeping Formations (Salt, Clay) 1273.3.2.2 Formation Pressure and Formation Damage (Hydrostatic Head, Ecd) 1273.4 Casing and Cementation 1283.4.1 Casing and Liner Concepts 1293.4.2 Casing Materials 1293.4.3 Pipe Centralization 1313.4.4 Cementation 1323.4.5 Cement Slurries, ECD 1333.4.6 Influence of Temperature on Casing and Cement 1363.5 Planning a Well 1363.5.1 Geological Forecast 1363.5.1.1 Target Definition 1373.5.1.2 Pore Pressures/Fracture Pressure/Temperature 1373.5.1.3 Critical Formations/Fault Zones 1383.5.1.4 Hydrocarbon Bearing Formations 1383.5.1.5 Permeabilities 1383.5.2 Well Design 1393.5.2.1 Trajectory 1393.5.2.2 Casing Setting Depths 1393.5.2.3 Casing Sizes 1393.5.2.4 Casing String Design 1403.6 Drilling a Well 1423.6.1 Contract Types and Influence on Project Organization 1423.6.1.1 Turnkey Contract 1423.6.1.2 Meter-contract 1433.6.1.3 Time-based Contract 1433.6.1.4 Incentive Contract 1433.6.2 Site Preparation and Infrastructure 1443.6.2.1 General 1443.6.2.2 Excavating and Trenching 1443.6.2.3 Environmental Impact (Noise, Pollution Prevention) 1443.6.3 Drilling Operations 1443.6.4 Problems and Trouble Shooting 1453.7 Well Completion Techniques 1483.7.1 Casing (Please Refer Also to ‘‘Casing String Design’’) 1483.7.1.1 Allowance of Vertical Movement of Casing 1483.7.1.2 Pretensioning 1483.7.1.3 Liner in Pay Zone (Slotted/Predrilled) or Barefoot Completion 1503.7.2 Wellheads, Valves and so on 1503.7.3 Well Completion without Pumps with Naturally Flowing Wells 1513.7.4 Well Completion with Pumps 1523.8 Risks 1523.8.1 Evaluating Risks 1533.8.1.1 Poor or Wrong Geological Profile Forecast 1533.8.1.2 Poor Well Design 1533.8.2 Technical Risks 1543.8.2.1 Failure of Surface Equipment 1543.8.2.2 Failure of Subsurface Equipment 1543.8.3 Geological–Technical Risks 1553.8.4 Geological Risks 1573.8.5 Geotectonical Risks 1593.9 Case Study Groß Schönebeck Well 1593.10 Economics (Drilling Concepts) 1623.10.1 Influence of Well Design on Costs 1643.10.1.1 Casing Scheme 1643.10.1.2 Vertical Wells versus Deviated Wells 1653.11 Recent Developments, Perspectives in R&D 1653.11.1 Technical Trends 1653.11.1.1 Topdrive 1663.11.1.2 Rotary Steerable Systems (RSS) 1663.11.1.3 Multilateral Wells 1693.11.2 Other R&D-Themes of high Interest 169References 1704 Enhancing Geothermal Reservoirs 173Thomas Schulte, Günter Zimmermann, Francois Vuataz, Sandrine Portier, Torsten Tischner, Ralf Junker, Reiner Jatho, and Ernst Huenges4.1 Introduction 1734.1.1 Hydraulic Stimulation 1744.1.2 Thermal Stimulation 1744.1.3 Chemical Stimulation 1744.2 Initial Situation at the Specific Location 1744.2.1 Typical Geological Settings 1744.2.2 Appropriate Stimulation Method According to Geological System and Objective 1754.3 Stimulation and Well path Design 1764.4 Investigations Ahead of Stimulation 1784.5 Definition and Description of Methods (Theoretical) 1804.5.1 Hydraulic Stimulation 1804.5.1.1 General 1804.5.1.2 Waterfrac Treatments 1814.5.1.3 Gel-Proppant Treatments 1824.5.1.4 Hybrid Frac Treatments 1834.5.2 Thermal Stimulation 1834.5.3 Chemical Stimulation 1844.6 Application (Practical) 1874.6.1 Hydraulic Stimulation 1874.6.1.1 Induced Seismicity 1894.6.2 Thermal Stimulation 1934.6.3 Chemical Stimulation 1944.7 Verification of Treatment Success 1974.7.1 General 1974.7.1.1 Wireline Based Evaluation 1974.7.1.2 Hydraulic Well Tests 1974.7.1.3 Tracer Testing 1984.7.1.4 Monitoring Techniques 2004.7.2 Evaluation of Chemical Stimulations 2014.8 Outcome 2024.8.1 Hydraulic Stimulation 2024.8.1.1 Hydraulic Stimulation – Soultz 2024.8.1.2 Hydraulic Stimulation Groß Schönebeck 2034.8.2 Thermal Stimulation 2044.8.3 Chemical Stimulation 2044.9 Sustainability of Treatment 2064.9.1 Hydraulic Stimulation 2064.9.1.1 Proppant Selection 2064.9.1.2 Coated Proppants 2094.9.2 Thermal Stimulation 2094.9.3 Chemical Stimulation 2104.10 Case Studies 2104.10.1 Groß Schönebeck 2104.10.1.1 Introduction 2104.10.1.2 Hydraulic Fracturing Treatments in GrSk3/ 90 2114.10.1.3 Hydraulic Fracturing in Sandstones (Gel-Proppant Stimulation) 2114.10.1.4 Hydraulic fracturing in Volcanics (Waterfrac Stimulation) 2124.10.1.5 Hydraulic Fracturing Treatments in GrSk4/ 05 2134.10.1.6 Hydraulic Fracturing Treatment in Volcanics (Waterfrac Stimulation) 2144.10.1.7 Hydraulic Fracturing in Sandstones (Gel-Proppant Stimulation) 2154.10.1.8 Conclusions 2164.10.2 Soultz 2174.10.2.1 Hydraulic Stimulation 2174.10.2.2 Chemical Stimulation 2234.10.3 Horstberg 2264.10.3.1 Introduction 2264.10.3.2 Fracturing Experiments 2284.10.3.3 Summary and Conclusion 232References 233Further Reading 2405 Geothermal Reservoir Simulation 245Olaf Kolditz, Mando Guido Blöcher, Christoph Clauser, Hans-Jörg G. Diersch, Thomas Kohl, Michael Kühn, Christopher I. McDermott, Wenqing Wang, Norihiro Watanabe, Günter Zimmermann, and Dominique Bruel5.1 Introduction 2455.1.1 Geothermal Modeling 2465.1.2 Uncertainty Analysis 2475.2 Theory 2485.2.1 Conceptual Approaches 2485.2.2 THM Mechanics 2485.2.2.1 Heat Transport 2495.2.2.2 Liquid Flow in Deformable Porous Media 2505.2.2.3 Thermoporoelastic Deformation 2505.3 Reservoir Characterization 2505.3.1 Reservoir Properties 2515.3.1.1 Reservoir Permeability 2515.3.1.2 Poroperm Relationships 2515.3.2 Fluid Properties 2545.3.2.1 Density and Viscosity 2545.3.2.2 Heat Capacity and Thermal Conductivity 2555.3.3 Supercritical Fluids 2575.3.4 Uncertainty Assessment 2585.4 Site Studies 2605.5 Groß Schönebeck 2605.5.1 Introduction 2605.5.2 Model Description 2615.5.2.1 Geology 2615.5.2.2 Structure 2625.5.2.3 Thermal Conditions 2635.5.2.4 Hydraulic Conditions 2635.5.3 Modeling Approach 2645.5.4 Results 2655.5.5 Conclusions 2685.6 Bad Urach 2685.6.1 The Influence of Parameter Uncertainty on Reservoir Evolution 2685.6.1.1 Conceptual Model 2685.6.1.2 Simulation Results 2705.6.1.3 Stimulated Reservoir Model 2705.6.1.4 Monte Carlo Analysis 2715.6.1.5 Conclusions 2755.6.2 The Influence of Coupled Processes on Differential Reservoir Cooling 2755.6.2.1 Conceptual Model 2755.6.2.2 Development of Preferential Flow Paths due to Positive Feedback Loops in Coupled Processes and Potential Reservoir Damage 2765.6.3 The Importance of Thermal Stress in the Rock Mass 2785.7 Rosemanowes (United Kingdom) 2795.8 Soultz-sous-Forets (France) 2805.9 KTB (Germany) 2845.9.1 Introduction 2845.9.2 Geomechanical Facies and Modeling the HM Behavior of the KTB Pump Test 2855.10 Stralsund (Germany) 2875.10.1 Site Description 2905.10.2 Model Setup 2905.10.3 Long-Term Development of Reservoir Properties 291References 2936 Energetic Use of EGS Reservoirs 303Ali Saadat, Stephanie Frick, Stefan Kranz, and Simona Regenspurg6.1 Utilization Options 3036.1.1 Energetic Considerations 3036.1.2 Heat Provision 3066.1.3 Chill Provision 3086.1.4 Power Provision 3126.2 EGS Plant Design 3166.2.1 Geothermal Fluid Loop 3166.2.1.1 Fluid Properties 3176.2.1.2 Operational Reliability Aspects 3236.2.1.3 Fluid Production Technology 3296.2.2 Heat Exchanger 3326.2.2.1 Heat Exchanger Analysis – General Considerations 3336.2.2.2 Selection of Heat Exchangers 3356.2.2.3 Specific Issues Related to Geothermal Energy 3376.2.3 Direct Heat Use 3386.2.4 Binary Power Conversion 3416.2.4.1 General Cycle Design 3426.2.4.2 Working Fluid 3476.2.4.3 Recooling Systems 3526.2.5 Combined Energy Provision 3596.2.5.1 Cogeneration 3596.2.5.2 Serial Connection 3606.2.5.3 Parallel Connection 3616.3 Case Studies 3626.3.1 Power Provision 3636.3.1.1 Objective 3636.3.1.2 Design Approach 3636.3.1.3 Gross Power versus Net Power Maximization 3646.3.2 Power and Heat Provision 3666.3.2.1 Objective 3666.3.2.2 Design Approach 3676.3.2.3 Serial versus Parallel Connection 367References 3687 Economic Performance and Environmental Assessment 373Stephanie Frick, Jan Diederik Van Wees, Martin Kaltschmitt, and Gerd Schröder7.1 Introduction 3737.2 Economic Aspects for Implementing EGS Projects 3757.2.1 Levelized Cost of Energy (LCOE) 3757.2.1.1 Methodological Approach 3767.2.1.2 Cost Analysis 3777.2.1.3 Case Studies 3837.2.2 Decision and Risk Analysis 3937.2.2.1 Methodology 3947.2.2.2 Case Study 3977.3 Impacts on the Environment 4057.3.1 Life Cycle Assessment 4067.3.1.1 Methodological Approach 4067.3.1.2 Case Studies 4087.3.2 Impacts on the Local Environment 4127.3.2.1 Local Impacts 4127.3.2.2 Environmental Impact Assessment 417References 4198 Deployment of Enhanced Geothermal Systems Plants and CO 2 Mitigation 423Ernst Huenges8.1 Introduction 4238.2 CO 2 Emission by Electricity Generation from Different Energy Sources 4238.3 Costs of Mitigation of CO 2 Emissions 4248.4 Potential Deployment 4268.5 Controlling Factors of Geothermal Deployment 4268.5.1 Technological Factors 4268.5.2 Economic and Political Factors 427References 428Color Plates 429Index 445