Catalogue Preface List of Tables List of Figures Abbreviations Nomenclature Chapter 1 Introduction 1 1.1 Background 1 1.2 Motivation 3 1.3 Production Wells of Open Systems 6 1.4 Literature Review 9 1.5 Study Contents, Objectives and Research Methods 15 1.5.1 Study Contents 15 1.5.2 Objectives 19 1.5.3 Research Methods 19 Chapter 2 Heat Transfer in the Surroundings 22 2.1 Factors Affecting the Formation Temperature 22 2.1.1 Geological Configuration 22 2.1.2 Groundwater Activity 23 2.1.3 Radiogenic Heat Production of Rock 24 2.1.4 Palaeoclimate 25 2.1.5 Magma Heat 26 2.2 Prediction of Initial Formation Temperature 26 2.2.1 Introduction 27 2.2.2 Governing Equation 28 2.2.3 Field Example 29 2.2.4 Discussion 32 2.2.5 Optimized Temperature Distribution 34 2.3 Heat Transfer in an Aquifer 37 2.3.1 Introduction 37 2.3.2 Fractal Model 38 2.3.3 Advection Effect in Aquifers 44 2.3.4 Field Example 47 Chapter 3 Heat Transfer in the Wellbore 55 3.1 Heat Flow in the Tubing 56 3.1.1 Two-phase Flow 56 3.1.2 Convection of Two-phase Flow 63 3.1.3 Convective Equations for Geothermal Wells 68 3.2 Heat Transfer in the Annulus 68 3.2.1 Introduction 69 3.2.2 Heat Transfer Mechanism 70 3.2.3 Results and Discussions 75 Chapter 4 Mathematical Model Establishment 84 4.1 Mathematical Model 84 4.1.1 Assumptions and Delamination for Formation 85 4.1.2 Heat Transfer in the Surroundings 86 4.1.3 Heat Transfer in the Wellbore 90 4.2 Calculation Processes 100 Chapter 5 Model Simulation 103 5.1 Parameters Assumption 103 5.2 Model Realization 104 5.3 Simulation Scenarios 107 5.3.1 Production Time and Flow Rate 107 5.3.2 Wellbore Structure 110 5.3.3 Annulus and Cement 110 5.3.4 Geological Conditions 114 5.3.5 Optimization 116 Chapter 6 Model Application 118 Chapter 7 Conclusions 124 7.1 Prediction of IFT 124 7.2 Heat Transfer in an Aquifer 125 7.3 Total Thermal Conductivity in the Annulus 125 7.4 Model Establishment and Simulation 126 7.5 Model Application 127 Chapter 8 Summary 129 References 131 List of Tables Table 2.1 The Measured Thermophysical Properties of PP1 and PP2 Changed from Wang et al. (2001) 30 Table 2.2 The Results of T (z) Predicted by Equation (2.6), Equation (2.7),Equation (2.8) and Equation (2.9) 31 Table 2.3 The Values of Ts and λs in PP1 and PP2 34 Table 2.4 The Predicted Bottom Temperature of the Main Borehole 35 Table 2.5 Properties of Typical Aquifers Changed from Chiasson (1996) 39 Table 2.6 Conductive and Advective Portions of λe of Various Aquifers with Different Velocities 45 Table 2.7 Physical and Thermophysical Parameters of Each Layer from Zhou (2007) 48 Table 2.8 Results of the three Methods 54 Table 3.1 The Summary of Different Formulae for Calculating Heat Coefficient Changed from Yu (2007) 63 Table 3.2 Sizes of Tubing and Casing Changed from Gabolde and Nguyen (1991) 72 Table 3.3 The Physical Properties of Dry Air (p=1.013,25×105 Pa) Changed from Yang and Tao (1998) 74 Table 3.4 The Physical Properties of Saturated Water Changed from Yang and Tao (1998) 74 Table 5.1 Description of Wellbore Configuration 103 Table 5.2 Geological Conditions of the Surroundings 103 Table 5.3 Information of Production 104 Table 5.4 The Results of Modeling Calculation 105 Table 5.5 The Data of Wellbore Structure 110 Table 6.1 The Parameters of Wells 118 Table 6.2 The Predicted Formation Temperatures of Jundian5 and Luowu at Different Depths 119 List of Figures Figure 1.1 The World Energy Consumption of Primary Energy (Million Tones Oil Equivalent) from BP Company (2012) 1 Figure 1.2 Structures of Total Renewable Energy Supplies in the EU in 2005 and 2020 from ECN (2011) 4 Figure 1.3 Sketches of a Steam Turbine and a Binary Plant; from Dickson and Fanelli (2005) 5 Figure 1.4 Sketch of the Production Wellbore Structure (The Underground Part is Symmetrical Along z-axis) Changed from DiPippo (2012) 9 Figure 1.5 Sketch of Academic Route 21 Figure 2.1 The Predicted Temperature Distribution of the Main Borehole 31 Figure 2.2 The Optimized Temperature Distribution of the Main Borehole 34 Figure 2.3 The Calculated and Measured IFT Distribution of the Main Borehole 36 Figure 2.4 Microcosmic Structure Section of an Aquifer Changed from Chen and Shi (1999) 41 Figure 2.5 The Elementary Volume of the Aquifer 42 Figure 2.6 Sketch of Thermal Resistances Structure 43 Figure 2.7 Conductive and Advective Portions of λe of Various Aquifers with Different Porosity 46 Figure 2.8 The Logarithmic Relationship Between Velocity and Advective Portion 47 Figure 2.9 Lithology of the Exploratory Holes from Zhou (2007) 51 Figure 2.10 Tm and Tcal with Time of Hole No.1 (left), No.2 (middle) and No.3 (right); from Zhou (2007) 52 Figure 2.11 Mean Temperatures of the Holes and Their Slope Curves from Zhou (2007) 53 Figure 3.1 Heat Transfer in the Underground System of a Geothermal Production Well Changed from Willhite (1967) 55 Figure 3.2 Pressure Distribution in the Wellbores Changed from Hu (1985) 57 Figure 3.3 Flow Patterns in Vertical Upward Flow Changed from Taitel et al. (1980) 59 Figure 3.4 Flow Regimes, Heat Transfer Regimes and Wall and Fluid Temperatures in Forced Convective Boiling Changed from Aziz et al. (1972) 61 Figure 3.5 Wellbore Structure of Open Geothermal Systems 69 Figure 3.6 Temperature Dependence of the Total, Normal Emissivity εn of Selected Materials from Incropera and DeWitt (2001) 76 Figure 3.7 Radiative Heat Transfer Coefficient in the Annulus 77 Figure 3.8 Ra of Air and Water Filling in the Annulus with Various Sizes 78 Figure 3.9 Ra of Air and Water Filling in the Annulus with Various Temperatures 78 Figure 3.10 hc of the Three Methods with Low Ra 79 Figure 3.11 hc of the Three Methods with High Ra 79 Figure 3.12 Equivalent Thermal Conductivity of Natural Convection When Air Fills in the Annulus 81 Figure 3.13 λtotal in the Annulus Filled with Air When the Material of the Tubing and the Casing is Polished Stainless Steel 81 Figure 3.14 λtotal in the Annulus Filled with Air when the Material of the Tubing and the Casing is Heavily Oxidized Stainless Steel 82 Figure 4.1 Physical Model of the Deep Geothermal Production Well 84 Figure 4.2 Energy Balance for Wellbore Fluid from Hasan and Kabir (2002) 91 Figure 4.3 The Flow Chart of Model Calculation 101 Figure 5.1 The IFT Distribution 106 Figure 5.2 The Temperature Distribution from the Tubing to the Formation 106 Figure 5.3 The Temperature Distribution of Heat Flow with Production Time 108 Figure 5.4 The Wellhead Temperature During Production Time with and Without the Convection Inside Tubing 109 Figure 5.5 The Wellhead Temperature with Mass Flow Rate 109 Figure 5.6 The Wellhead Temperature with Tubing Outside Diameter 111 Figure.5.7 The Wellhead Temperature with Casing Outside Diameter 111 Figure 5.8 The Wellhead Temperature with Wellbore Diameter 112 Figure 5.9 The Wellhead Temperature with Different Annulus Conditions 113 Figure 5.10 The Wellhead Temperature with Different Gases Filled in the Annulus 113 Figure 5.11 The Wellhead Temperature with the Conductivity of Cement 114 Figure 5.12 The Wellhead Temperature with Geological Conditions 115 Figure 5.13 The Optimized Curve of Temperature with Production Time 116 Figure 6.1 The Temperature Distributions of Different Ways 120 Figure 6.2 The Wellhead Temperature of Heat Flow with Various Temperatures and Mass Flow Rates of the Hot Air in the Annulus 122 Figure 6.3 The Sketch of the Supporting Device with Three Edges in the Annulus 123 Figure 6.4 The Temperature Distribution of Heat Flow When Vacuum Occurs in the Annulus 123