Page 8 - Geothermal Energy Renewable Energy and The Environment
P. 8
Contents vii
Case Study: The Silica System ...................................................................................85
Synopsis ......................................................................................................................86
References ..................................................................................................................87
Chapter 6. Exploring for Geothermal Systems ............................................................................ 91
Field Geology and Surface Manifestations ................................................................ 91
Volcanoes: Active and Dormant ............................................................................ 91
Faulting and Associated Rock Alteration ..............................................................92
Surface Deposits ....................................................................................................93
Geochemistry as an Exploration Tool ........................................................................95
Fluid Composition and Geothermometry ..............................................................95
Isotopes ................................................................................................................100
Geophysics as an Exploration Tool ..........................................................................104
Aeromagnetic Surveys .........................................................................................104
Resistivity and Magnetotelluric Surveys ............................................................. 105
Gravity Surveys ...................................................................................................107
Seismicity and Reflection Seismology ................................................................108
Temperature Measurements ................................................................................ 110
Remote Sensing as an Exploration Tool: A Promising New Technique .................. 111
Multispectral Studies ........................................................................................... 111
Case Study: Fallon, Nevada ..................................................................................... 113
Synposis .................................................................................................................... 115
References ................................................................................................................ 116
Further Information .................................................................................................. 118
Chapter 7. Resource Assessments .............................................................................................. 119
Assessing a Geothermal Resource ........................................................................... 119
Resource Base and Reserves ....................................................................................120
Uncertainty ..........................................................................................................120
Establishing the Reservoir Volume ..........................................................................122
Establishing the Reservoir Heat Content .................................................................123
The Significance of Heat Capacity ...........................................................................125
Efficiency of Heat Extraction ...................................................................................126
Case Study: Establishing the United States Geothermal Resource .........................129
Synopsis .................................................................................................................... 132
References ................................................................................................................ 133
Further Information ..................................................................................................134
Chapter 8. Drilling ..................................................................................................................... 135
Background .............................................................................................................. 135
Drilling for Ground Source Heat Pump and Direct Use Applications .................... 135
Drilling Equipment and Technology ...................................................................136
Drilling Fluid and Circulation ............................................................................. 137
Properties of Drilling Fluids .............................................................................. 139
Well Completion .................................................................................................. 140
Environmental Issues .......................................................................................... 140
Drilling for Geothermal Fluids for Power Generation ............................................. 141
Drilling Rigs ........................................................................................................ 141
