Geothermal/Exploration

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Geothermal Exploration

General
Techniques Tree
Techniques Table
Regulatory Roadmap

Geothermal springs along Yellowstone National Park’s Firehole River in the cool air of autumn. The world’s most environmentally sensitive geothermal features are protected by law.

Geothermal Exploration searches the earth’s subsurface for geothermal resources that can be extracted for the purpose of electricity generation. A geothermal resource is as commonly a volume of hot rock and water, but in the case of EGS, is simply hot rock. Geothermal exploration programs utilize a variety of techniques to identify geothermal reservoirs as well as information that can point to areas of low density, high porosity, high permeability, and subsurface fault lines that can help define well field development.

Groups of Exploration Techniques

There are many different techniques that are utilized in geothermal exploration depending on the region’s geology, economic considerations, project maturity, and other considerations such as land access and permitting requirements. Geothermal techniques can be broken into the following categories:

Full List of Exploration Techniques

Exploration Phases

Geothermal exploration is commonly separated into phases - a set of techniques that the developer will use to determine if a location is worth investigating further. Many geothermal developers define phases based on economic considerations and permitting requirements. Typically a developer will perform the least expensive techniques earlier on in the exploration program to reduce the risk of drilling a well with inadequate temperatures or flow. For example many developers will start with a desktop analysis, which includes a review of existing exploration techniques, a site visit, and in some cases inexpensive remote sensing techniques. If that set of techniques shows favorable conditions the developer will move on to the next phase. It is not uncommon for developers to start exploration at 5-10 locations and only drill at 1 location.

Note: The exploration phases described here should not be confused with the GEA Development Phases. The GEA Development Phases are used for reporting which stage in development a power plant is in (i.e. Procurement, Exploration, Permitting, Construction)^[1].

Typical Exploration Phases^[2]

Phase 1 - Regional Reconnaissance: for example: Geothermal Literature Review, Geothermometry, Multispectral Imaging, Data Acquisition-Manipulation

Phase 2 - Prospect Evaluation: for example: Hyperspectral Imaging, Compound and Elemental Analysis, Geothermometry, Field Mapping, Modeling-Computer Simulations

Phase 3 - Project Appraisal: for example: Geophysical Techniques, Field Mapping, Modeling-Computer Simulations

Phase 4 - Exploratory Drilling: for example: Thermal Gradient Holes, Core Holes, Slim Holes, Modeling-Computer Simulations

Exploration Best Practices

At a workshop in March 2013, IFC (International Finance Corporation), a member of the Word Bank Group, together with the International Geothermal Association launched “Geothermal Exploration Best Practices: A Guide to Resource Data Collection, Analysis, and Presentation for Geothermal Projects” in Istanbul, Turkey.

This Best Practice Guide for Geothermal Exploration was produced for IFC by GeothermEx, Inc. and outlines procedures and exploration techniques for geothermal projects and provides guidelines for presenting a geothermal project to funding entities and insurance companies. A focus is placed on high temperature geothermal resources for electricity generation. Project focus is also to attract potential investors by mitigating the associated risks with the help of insurance companies.

Full Report:
Geothermal Exploration Best Practices: A Guide to Resource Data Collection, Analysis and Presentation for Geothermal Projects

Exploration Cost and Time

The costs of exploration and the time required to complete an exploration program both add to the risk associated with the development of geothermal power plants. A typical geothermal exploration program for an individual location may require a financial commitment of 7 Million USD prior to drilling the first exploration hole^[2]. The time required to bring a geothermal power plant online in many cases is at least 3-5 years with the majority of that time due to exploration^[3]. In the case of Glass Mountain KGRA in Northern California the permitting delays were significant enough that it took over 20 years to complete an exploration program^[3].

A representation of the cost and time commitments required for a typical geothermal exploration program can be viewed and modified using the Exploration Cost and Time Metric tool that was developed from a collaboration between government and industry.

Looking for exploration techniques that might provide Structural Information? Thermal Information? This query has been included to allow you to use the black arrows in the table header cells to sort the table data.

Technique	Exploration Group	Exploration Sub Group	Lithology Info Provided	Structure/Stratigraphic Info Provided	Hydrologic Info Provided	Thermal Info Provided
2-M Probe Survey	Drilling Techniques	Exploration Drilling				Identify and delineate shallow thermal anomalies
Acoustic Logs	Downhole Techniques	Well Log Techniques		map discontinuities to determine their orientation.
Active Seismic Methods	Geophysical Techniques	Seismic Techniques
Active Seismic Techniques	Geophysical Techniques	Seismic Techniques	Rock unit density influences elastic wave velocities.	Structural geology- faults, folds, grabens, horst blocks, sedimentary layering, discontinuities, etc.	Combining compressional and shear wave results can indicate the presence of fluid saturation in the formation.	High temperatures and pressure impact the compressional and shear wave velocities.
Active Sensors	Remote Sensing Techniques Remote Sensing Techniques	Active Sensors
Aerial Photography	Remote Sensing Techniques	Passive Sensors		map structures/faults	map surface water features	if photos taken in winter snow cover, can map thermal anomalies
Aeromagnetic Survey	Geophysical Techniques	Magnetic Techniques		map structure, basin fill thickness, and magnetic mineral concentrations in ore bodies
Airborne Electromagnetic Survey	Geophysical Techniques	Electrical Techniques	provide data on rock type and mineral content		can be used to detect changes in density of fluids and indicate if there is salt water intrusion
Airborne Gravity Survey	Geophysical Techniques	Gravity Techniques	Distribution of density in the subsurface enables inference of rock type.	Delineation of steeply dipping formations, geological discontinuities and faults, intrusions and the deposition of silicates due to hydrothermal activity.	Density of sedimentary rocks are strongly influenced by fluid contained within pore space. Dry bulk density refers to the rock with no moisture, while the wet bulk density accounts for water saturation; fluid content may alter density by up to 30%.(Sharma, 1997)	Determination of potential heat source of the system related to the low density signature of molten intrusions. (Bruhn, 2010)
Analytical Modeling	Data and Modeling Techniques	Modeling Techniques
Audio-Magnetotellurics	Geophysical Techniques	Electrical Techniques	Rock composition, mineral and clay content	Detection of permeable pathways, fracture zones, faults	Resistivity influenced by porosity, grain size distribution, permeability, fluid saturation, fluid type and phase state of the pore water	Resistivity influenced by temperature
Borehole Seismic Techniques	Downhole Techniques	Borehole Seismic Techniques	Rock unit density influences elastic wave velocities	Structural geology- faults, folds, grabens, horst blocks, sedimentary layering, discontinuities, etc	Combining compressional and shear wave results can indicate the presence of fluid saturation in the formation	High temperatures and pressure impact the compressional and shear wave velocities
Caliper Log	Downhole Techniques	Well Log Techniques
Cation Geothermometers	Geochemical Techniques	Geochemical Data Analysis
Cement Bond Log	Downhole Techniques	Well Log Techniques
Chemical Logging	Field Techniques	Field Techniques			Presence and geochemical composition of fluid producing zones	Calcium-alkalinity ratios versus depth assist in defining warm and hot water aquifers
Compound and Elemental Analysis	Lab Analysis Techniques	Fluid Lab Analysis			results can aid in the determination of fluid source regions and circulation pathways	certain elements exhibit high spatial correlation with high-temperature geothermal systems
Conceptual Model	Data and Modeling Techniques	Modeling Techniques
Controlled Source Audio MT	Geophysical Techniques	Electrical Techniques	Rock composition, mineral and clay content	Detection of permeable pathways, fracture zones, faults	Resistivity influenced by porosity, grain size distribution, permeability, fluid saturation, fluid type and phase state of the pore water	Resistivity influenced by temperature
Controlled Source Frequency-Domain Magnetics	Geophysical Techniques	Magnetic Techniques			Locate geothermal groundwater and flow patterns.
Core Analysis	Lab Analysis Techniques	Rock Lab Analysis	Core analysis is done to define lithology	Core analysis can locate faults or fracture networks. Oriented core can give additional important information on anisotropy		Thermal conductivity can be measured from core samples
Core Holes	Drilling Techniques	Exploration Drilling	Core holes are drilled to identify lithology and mineralization	Retrieved samples can be used to identify fracture networks or faults		Thermal conductivity measurements can be done on retrieved samples.
Cross-Dipole Acoustic Log	Downhole Techniques	Well Log Techniques			Use for fracture identification in open and cased holes. Also used for for evaluating hydro fracturing/well stimulation effectiveness.
Cuttings Analysis	Lab Analysis Techniques	Rock Lab Analysis	Cuttings are used to define lithology
DC Resistivity Survey (Dipole-Dipole Array)	Geophysical Techniques	Electrical Techniques	Rock composition, mineral and clay content	Detection of permeable pathways, fracture zones, faults	Resistivity influenced by porosity, grain size distribution, permeability, fluid saturation, fluid type and phase state of the pore water	Resistivity influenced by temperature
DC Resistivity Survey (Gradient Array)	Geophysical Techniques	Electrical Techniques
DC Resistivity Survey (Pole-Dipole Array)	Geophysical Techniques	Electrical Techniques	Rock composition, mineral and clay content	Detection of permeable pathways, fracture zones, faults	Resistivity influenced by porosity, grain size distribution, permeability, fluid saturation, fluid type and phase state of the pore water	Resistivity influenced by temperature
DC Resistivity Survey (Schlumberger Array)	Geophysical Techniques	Electrical Techniques	Rock composition, mineral and clay content	Detection of permeable pathways, fracture zones, faults	Resistivity influenced by porosity, grain size distribution, permeability, fluid saturation, fluid type and phase state of the pore water	Resistivity influenced by temperature
DC Resistivity Survey (Wenner Array)	Geophysical Techniques	Electrical Techniques	Rock composition, mineral and clay content	Detection of permeable pathways, fracture zones, faults	Resistivity influenced by porosity, grain size distribution, permeability, fluid saturation, fluid type and phase state of the pore water	Resistivity influenced by temperature
Data Acquisition-Manipulation	Data and Modeling Techniques	Data Techniques
Data Collection and Mapping	Field Techniques	Data Collection and Mapping
Data Techniques	Data and Modeling Techniques	Data Techniques
Data and Modeling Techniques	Data and Modeling Techniques
Density Log	Downhole Techniques	Well Log Techniques	provides data on the bulk density of the rock surrounding the well	Stratigraphic correlation between well bores.	Porosity of the formations loggesd can be calculated for the Density log andprovide an indication potential aquifers.
Development Drilling	Drilling Techniques	Development Drilling
Direct-Current Resistivity Survey	Geophysical Techniques Geophysical Techniques	Electrical Techniques	Rock type, mineral and clay content may be inferred.	Determination of fracture zones, faults, depth to groundwater aquifers.	Resistivity influenced by porosity, permeability, fluid saturation, fluid type and phase state of the pore water.
Downhole Techniques	Downhole Techniques		Determination of lithology, grain size	Thickness and geometry of rock strata, fracture identification	Porosity, permeability, water saturation	Formation temperature with depth
Drilling Methods
Drilling Techniques	Drilling Techniques
Earth Tidal Analysis	Downhole Techniques	Well Testing Techniques	Enables estimation of in-situ reservoir elastic parameters.		Enables estimation of in-situ reservoir hydraulic parameters.
Electric Micro Imager Log	Downhole Techniques	Well Log Techniques
Electrical Profiling Configurations	Geophysical Techniques	Electrical Techniques	Rock composition, mineral and clay content	Detection of permeable pathways, fracture zones, faults	Resistivity influenced by porosity, grain size distribution, permeability, fluid saturation, fluid type and phase state of the pore water	Resistivity influenced by temperature
Electrical Techniques	Geophysical Techniques	Electrical Techniques	Rock composition, mineral and clay content	Detection of permeable pathways, fracture zones, faults	Resistivity influenced by porosity, grain size distribution, permeability, fluid saturation, fluid type and phase state of the pore water	Resistivity influenced by temperature
Electromagnetic Profiling Techniques	Geophysical Techniques	Electrical Techniques	Rock composition, mineral and clay content	Detection of permeable pathways, fracture zones, faults	Resistivity influenced by porosity, grain size distribution, permeability, fluid saturation, fluid type and phase state of the pore water	Resistivity influenced by temperature
Electromagnetic Sounding Techniques	Geophysical Techniques	Electrical Techniques	Rock composition, mineral and clay content	Detection of permeable pathways, fracture zones, faults	Resistivity influenced by porosity, grain size distribution, permeability, fluid saturation, fluid type and phase state of the pore water	Resistivity influenced by temperature
Electromagnetic Techniques	Geophysical Techniques	Electrical Techniques	Rock composition, mineral and clay content	Detection of permeable pathways, fracture zones, faults	Resistivity influenced by porosity, grain size distribution, permeability, fluid saturation, fluid type and phase state of the pore water	Resistivity influenced by temperature
Elemental Analysis with Fluid Inclusion	Lab Analysis Techniques	Fluid Lab Analysis
Exploration Drilling	Drilling Techniques	Exploration Drilling
Exploratory Boreholes	Drilling Techniques	Exploration Drilling
Exploratory Well	Drilling Techniques	Exploration Drilling	Can provide core or cuttings	Identify stratigraphy and structural features within a well	-Water samples can be used for geochemical analysis -Fluid pressures can be used to estimate flow rates	-Temperatures can be measured within the hole -Information about the heat source
FLIR	Remote Sensing Techniques	Passive Sensors				Map surface temperatures
FMI Log	Downhole Techniques	Well Log Techniques
Fault Mapping	Field Techniques	Data Collection and Mapping		Locates active faults in the area of interest	Can reveal whether faults are circulating hydrothermal fluids
Field Mapping	Field Techniques	Data Collection and Mapping	map surface geology	map fault and fracture patterns, kinematic information	map surface manifestations of geothermal systems	map surface temperature
Field Sampling	Field Techniques	Field Sampling
Field Techniques	Field Techniques
Flow Test	Downhole Techniques	Well Testing Techniques			Flow tests provide information on permeability, recharge rates, reservoir pressures, fluid chemistry, and scaling.	Flow tests can measure temperature variations with time to estimate characteristics about the heat source.
Fluid Inclusion Analysis	Lab Analysis Techniques	Fluid Lab Analysis			Fluid composition at a point in time and space	The minimum temperature of fluid inclusion formation
Fluid Lab Analysis	Lab Analysis Techniques	Fluid Lab Analysis
Formation Testing Techniques	Downhole Techniques	Formation Testing Techniques
Frequency-Domain Electromagnetic Survey	Geophysical Techniques	Electrical Techniques	Detection of high-conductivity bodies in the subsurface. Detection of high-conductivity bodies in the subsurface.			Detection of the presence of a thermal anomaly through its resistivity signature. Detection of the presence of a thermal anomaly through its resistivity signature.
Gamma Log	Downhole Techniques	Well Log Techniques	provides information on changes in rock type near the wellbore from changes in measured gamma radiation	using multiple gamma logs over an area, the depth to the sandstone and shale layers can be correlated over larger areas
Gas Flux Sampling	Field Techniques	Field Sampling		High flux can be indicative of conduits for fluid flow		Anomalous flux is associated with active hydrothermal activity
Gas Geothermometry	Geochemical Techniques	Geochemical Data Analysis
Gas Sampling	Field Techniques	Field Sampling
Geochemical Data Analysis	Geochemical Techniques	Geochemical Data Analysis
Geochemical Techniques	Geochemical Techniques
Geodetic Survey	Remote Sensing Techniques	Passive Sensors		Map regional strain rates
Geographic Information System	Data and Modeling Techniques	Data Techniques	Any mapable information	Any mapable information	Any mapable information	Any mapable information
Geophysical Methods	Geophysical Techniques	Geophysical Techniques
Geophysical Techniques	Geophysical Techniques		may be inferred	may be inferred	may be inferred	may be inferred
Geothermal Literature Review	Data and Modeling Techniques	Data Techniques
Geothermometry	Geochemical Techniques	Geochemical Data Analysis				used to estimate reservoir temperatures
Gravity Methods	Geophysical Techniques	Gravity Techniques
Gravity Techniques	Geophysical Techniques	Gravity Techniques	Distribution of density in the subsurface enables inference of rock type.	Delineation of steeply dipping formations, geological discontinuities and faults, intrusions and the deposition of silicates due to hydrothermal activity.	Density of sedimentary rocks are strongly influenced by fluid contained within pore space. Dry bulk density refers to the rock with no moisture, while the wet bulk density accounts for water saturation; fluid content may alter density by up to 30%.(Sharma, 1997)	Determination of potential heat source of the system related to the low density signature of molten intrusions. (Bruhn, 2010)
Ground Electromagnetic Techniques	Geophysical Techniques	Electrical Techniques	Rock composition, mineral and clay content	Detection of permeable pathways, fracture zones, faults	Resistivity influenced by porosity, grain size distribution, permeability, fluid saturation, fluid type and phase state of the pore water	Resistivity influenced by temperature
Ground Gravity Survey	Geophysical Techniques	Gravity Techniques	Distribution of density in the subsurface enables inference of rock type.	Delineation of steeply dipping formations, geological discontinuities and faults, intrusions and large-scale deposition of silicates due to hydrothermal activity.	Density of sedimentary rocks are strongly influenced by fluid contained within pore space. Dry bulk density refers to the rock with no moisture, while the wet bulk density accounts for water saturation; fluid content may alter density by up to 30%.(Sharma, 1997)	Determination of potential heat source of the system related to the low density signature of molten intrusions. (Bruhn, 2010)
Ground Magnetics	Geophysical Techniques	Magnetic Techniques	Presence of magnetic minerals such as magnetite.	Mapping of basement structures, horst blocks, fault systems, fracture zones, dykes and intrusions.	The circulation of hydrothermal fluid may impact the magnetic susceptibility of rocks.
Groundwater Sampling	Field Techniques	Field Sampling
Hydroprobe	Drilling Techniques	Exploration Drilling
Hyperspectral Imaging	Remote Sensing Techniques	Passive Sensors	mineral maps can be used to show the presence of hydrothermal minerals and mineral assemblages	aerial photographs can show structures	delineate locations of surface water features	vegetation maps can show plants stressed due to nearby thermal activity
Image Logs	Downhole Techniques	Well Log Techniques
InSAR	Remote Sensing Techniques	Active Sensors		Geophysical Monitoring
Injectivity Test	Downhole Techniques	Well Testing Techniques
Isotope Geothermometry	Geochemical Techniques	Geochemical Data Analysis
Isotopic Analysis	Lab Analysis Techniques	Fluid Lab Analysis			Source of fluids, circulation, and/or mixing.	Heat source and general reservoir temperatures
Isotopic Analysis- Fluid	Lab Analysis Techniques	Fluid Lab Analysis	Water rock interaction		Origin of hydrothermal fluids Mixing of hydrothermal fluids	Isotopic ratios can be used to characterize and locate subsurface thermal anomalies.
Isotopic Analysis- Rock	Lab Analysis Techniques	Rock Lab Analysis
Lab Analysis Techniques	Lab Analysis Techniques
LiDAR	Remote Sensing Techniques	Active Sensors		delineate faults, create high-resolution DEMS, quantify fault kinemaics, develop lineament maps
Liquid Geothermometry	Geochemical Techniques	Geochemical Data Analysis
Long-Wave Infrared	Remote Sensing Techniques	Passive Sensors
Macrophotography	Remote Sensing Techniques	Passive Sensors
Magnetic Techniques	Geophysical Techniques	Magnetic Techniques	Presence of magnetic minerals such as magnetite.	Mapping of basement structures, horst blocks, fault systems, fracture zones, dykes and intrusions.	The circulation of hydrothermal fluid may impact the magnetic susceptibility of rocks.
Magnetotelluric Methods	Geophysical Techniques	Electrical Techniques
Magnetotelluric Techniques	Geophysical Techniques	Electrical Techniques	Rock composition, mineral and clay content	Detection of permeable pathways, fracture zones, faults	Resistivity influenced by porosity, grain size distribution, permeability, fluid saturation, fluid type and phase state of the pore water	Resistivity influenced by temperature
Magnetotellurics	Geophysical Techniques	Electrical Techniques	Rock composition, mineral and clay content	Detection of permeable pathways, fracture zones, faults	Resistivity influenced by porosity, grain size distribution, permeability, fluid saturation, fluid type and phase state of the pore water	Resistivity influenced by temperature
Mercury Vapor	Lab Analysis Techniques	Fluid Lab Analysis		Anomalously high concentrations can indicate high permeability or conduit for fluid flow	Field wide soil sampling can generate a geometrical approximation of fluid circulation	High concentration in soils can be indicative of active hydrothermal activity
Micro-Earthquake	Geophysical Techniques	Seismic Techniques		Fault zones, permeable pathways	Fluid type- liquid or steam
Microgravity-Hybrid Microgravity	Geophysical Techniques	Gravity Techniques		Ground subsidence can be mapped using microgravity	Monitoring net mass changes of a geothermal reservoir due to production and reinjection processes	Changes in liquid density due to temperature changes in the reservoir
Modeling Techniques	Data and Modeling Techniques	Modeling Techniques
Modeling-Computer Simulations	Data and Modeling Techniques	Modeling Techniques
Mud Logging	Field Techniques	Field Sampling
Multicomponent Geothermometers	Geochemical Techniques	Geochemical Data Analysis
Multispectral Imaging	Remote Sensing Techniques	Passive Sensors	relative mineral maps	aerial photographs can show structures	delineate locations of surface water features
Multispectral Thermal Infrared	Remote Sensing Techniques	Passive Sensors
Near Infrared Surveys	Remote Sensing Techniques	Passive Sensors
Neutron Log	Downhole Techniques	Well Log Techniques	if used in conjunction with other logs, this can provide information on the rock type and the porosity	Corelation of rock units	Estimate for formation prrosity
Numerical Modeling	Data and Modeling Techniques	Modeling Techniques
Oblique Aerial & Ground Visible Band & Thermographic Imaging	Remote Sensing Techniques	Passive Sensors
Observation Wells	Drilling Techniques	Development Drilling			Total dissolved solids, fluid pressure, flow rates, and flow direction	Monitors temperature of circulating fluids
Optical Televiewer	Downhole Techniques	Well Log Techniques
Over Core Stress	Lab Analysis Techniques	Rock Lab Analysis
PSInSAR	Remote Sensing Techniques	Active Sensors
Paleomagnetic Measurements	Lab Analysis Techniques	Rock Lab Analysis
Passive Seismic Techniques	Geophysical Techniques	Seismic Techniques	Rock unit density influences elastic wave velocities.	Structural geology- faults, folds, grabens, horst blocks, sedimentary layering, discontinuities, etc.	Combining compressional and shear wave results can indicate the presence of fluid saturation in the formation.	High temperatures and pressure impact the compressional and shear wave velocities.
Passive Sensors	Remote Sensing Techniques	Passive Sensors
Petrography Analysis	Lab Analysis Techniques	Rock Lab Analysis	Provides detailed information about rock composition and morphology
Portfolio Risk Modeling	Data and Modeling Techniques	Modeling Techniques
Pressure Temperature Log	Downhole Techniques	Well Log Techniques		Perturbations in temperature or pressure can be indicative of faults or other structural features	fluid cirulation, over-pressured zones, and under-pressured zones.	Temperature profile with depth
Production Wells	Drilling Techniques Drilling Techniques	Development Drilling Development Drilling
Radar	Remote Sensing Techniques	Active Sensors
Radiometrics	Remote Sensing Techniques		Primary use is in mapping potassium alterations
Reflection Survey	Geophysical Techniques	Seismic Techniques	Rock unit density influences elastic wave velocities.	Structural geology- faults, folds, grabens, horst blocks, sedimentary layering, discontinuities, etc.	Combining compressional and shear wave results can indicate the presence of fluid saturation in the formation.	High temperatures and pressure impact the compressional and shear wave velocities.
Refraction Survey	Geophysical Techniques	Seismic Techniques	Rock unit density influences elastic wave velocities.	Can provide information on crustal thickness, depth to basement.
Remote Sensing Techniques	Remote Sensing Techniques Remote Sensing Techniques
Resistivity Log	Downhole Techniques	Well Log Techniques	Rock composition, mineral and clay content	Detection of permeable pathways, fracture zones, faults	Resistivity influenced by porosity, grain size distribution, permeability, fluid saturation, fluid type and phase state of the pore water	Resistivity influenced by temperature
Resistivity Tomography	Downhole Techniques	Well Log Techniques
Rock Density	Lab Analysis Techniques	Rock Lab Analysis
Rock Lab Analysis	Lab Analysis Techniques	Rock Lab Analysis
Rock Sampling	Field Techniques	Field Sampling	Rock samples are used to define lithology.	Provides information about the time and environment which formed a particular geologic unit. Microscopic rock textures can be used to estimate the history of stress and strain, and/or faulting.	Isotopic geochemistry can reveal fluid circulation of a geothermal system.	Thermal conductivity of a rock sample can provide information to calculate heat flow. Hydrothermal alteration of a rock sample can indicate certain temperature or fluid compositions.
SAR	Remote Sensing Techniques	Active Sensors		create high-resolution DEMs, detect fault and ground movement
SRT	Remote Sensing Techniques	Active Sensors		high-resolution DEMs
SWIR	Remote Sensing Techniques	Passive Sensors	map characteristic minerals associated with hot springs/mineral deposits
Seismic Techniques	Geophysical Techniques	Seismic Techniques	Rock unit density influences elastic wave velocities.	Structural geology- faults, folds, grabens, horst blocks, sedimentary layering, discontinuities, etc.	Combining compressional and shear wave results can indicate the presence of fluid saturation in the formation.	High temperatures and pressure impact the compressional and shear wave velocities.
Self Potential	Geophysical Techniques	Electrical Techniques	SP technique originally applied to locating sulfide ore-bodies.	Detection and tracing of faults.	Determination of fluid flow patterns: electrochemical coupling processes due to variations in ionic concentrations, and electrokinetic coupling processes due to fluid flow in the subsurface.	Location of near-surface thermal anomalies: thermoelectric coupling processes due to variations in temperature in the subsurface.
Silica Geothermometers	Geochemical Techniques	Geochemical Data Analysis
Single-Well And Cross-Well Seismic	Downhole Techniques	Borehole Seismic Techniques
Slim Holes	Drilling Techniques	Exploration Drilling	If core is collected	If core is collected	Fluid flow and water chemistry	Thermal gradient or bottom hole temperature
Soil Gas Sampling	Field Techniques	Field Sampling
Soil Sampling	Field Techniques	Field Sampling		Can reveal relatively high permeability zones		Used to locate active hydrothermal systems
Spontaneous Potential	Downhole Techniques	Well Log Techniques
Standard Slowness Log	Downhole Techniques	Well Log Techniques
Static Temperature Survey	Downhole Techniques	Well Testing Techniques
Stepout-Deepening Wells	Drilling Techniques	Development Drilling
Stereo Satellite Imagery	Remote Sensing Techniques	Passive Sensors
Stoneley Analysis	Downhole Techniques	Well Log Techniques
Stress Test	Downhole Techniques	Well Testing Techniques
Surface Gas Sampling	Field Techniques	Field Sampling
Surface Water Sampling	Field Techniques	Field Sampling
Teleseismic-Seismic Monitoring	Geophysical Techniques	Seismic Techniques	Rock unit density influences elastic wave velocities.	Map geothermal reservoir geometry. Structural geology- faults, folds, grabens, horst blocks, sedimentary layering, discontinuities, etc.	Combining compressional and shear wave results can indicate the presence of fluid saturation in the formation.	High temperatures and pressure impact the compressional and shear wave velocities.
Telluric Survey	Geophysical Techniques	Electrical Techniques	Rock composition, mineral and clay content	Detection of permeable pathways, fracture zones, faults	Resistivity influenced by porosity, grain size distribution, permeability, fluid saturation, fluid type and phase state of the pore water	Resistivity influenced by temperature
Thermal Gradient Holes	Drilling Techniques	Exploration Drilling			Field wide fluid flow characteristics if an array of wells are drilled	Mapping and projecting thermal anomalies
Thermal Ion Dispersion	Geochemical Techniques	Geochemical Data Analysis
Thermochronometry	Geochemical Techniques	Geochemical Data Analysis
Time-Domain Electromagnetics	Geophysical Techniques	Electrical Techniques	Detection of rock units or geological features with contrasting apparent resistivity.	Structural information may be inferred from TDEM data.	Hydrological information such as depth to groundwater table may be determined.	Extent of hydrothermal alteration mineralogy may be inferred.
Trace Element Analysis	Lab Analysis Techniques	Fluid Lab Analysis			Reconstructing the fluid circulation of a hydrothermal system
Tracer Testing	Downhole Techniques	Well Testing Techniques
Vertical Electrical Sounding Configurations	Geophysical Techniques	Electrical Techniques	Rock composition, mineral and clay content	Detection of permeable pathways, fracture zones, faults	Resistivity influenced by porosity, grain size distribution, permeability, fluid saturation, fluid type and phase state of the pore water	Resistivity influenced by temperature
Vertical Seismic Profiling	Downhole Techniques	Borehole Seismic Techniques	Rock unit density influences elastic wave velocities.	Structural geology- faults, folds, grabens, horst blocks, sedimentary layering, discontinuities, etc.	Combining compressional and shear wave results can indicate the presence of fluid saturation in the formation.	High temperatures and pressure impact the compressional and shear wave velocities.
Water Sampling	Field Techniques	Field Sampling			Water composition and source of fluids	Water temperature
Water-Gas Sampling	Field Techniques Field Techniques	Field Techniques Field Techniques
Well Log Techniques	Downhole Techniques	Well Log Techniques	depth and thickness of formations; lithology and porosity can be inferred	reservoir thickness, reservoir geometry, borehole geometry	permeability and fluid composition can be inferred	direct temperature measurements; thermal conductivity and heat capacity
Well Testing Techniques	Downhole Techniques	Well Testing Techniques
Z-Axis Tipper Electromagnetics	Geophysical Techniques	Electrical Techniques

Geothermal Regulatory Roadmap for Exploration

Overview Flowchart

The flowcharts listed below were developed as part of the Geothermal Regulatory Roadmap project. The roadmap covers the major regulatory requirements for developing geothermal energy, including, land access, exploration and drilling, plant construction and operation, transmission siting, water resource acquisition, and relevant environmental considerations.

Reading the Roadmap

The flowcharts are divided into General, Federal, and State sections to allow for ease of use. To use the flowcharts, start with General Flowchart for Exploration. The General Flowcharts will lead you to the federal and state flowcharts you will need. The overview flowchart on the right shows additional sections in the roadmap.

For more information on reading these flowcharts, Visit the "Getting Started" Section.
If you’d like to see regulations in other sections of the roadmap, see the entire listing of flowcharts
The GRR is continually being updated and added to. Some flowcharts have not yet been developed, but placeholders have been created. If you have input on any of these processes, please feel free to login to make updates, or .

Disclaimer

The flowcharts have been reviewed by relevant agency, developer and legal personnel, and are meant to serve as a guide to obtaining the permits needed for geothermal power plant development and a way to communicate the process among interested parties. This website is not intended to constitute legal advice or the provision of legal services. None of the individuals or agencies involved in developing this document warrant or certify that the information on this page is accurate. The services of a competent professional should be sought if legal or other specific expert assistance is required.

Overview Flowcharts

Section 4 - Exploration Overview

Federal Flowcharts

Section 4-FD-a - Exploration Application Process BLM
Section 4-FD-b - Exploration Pre-Application Process (NV only)
Section 4-FD-c - Exploration Application Process USFS

State Flowcharts

Exploration References

↑ "[http://www.geo-energy.org/reports/Factors%20Affecting%20Cost%20of%20Geothermal%20Power%20Development%20-%20August%202005.pdf Annual US Geothermal Power Production and Development Report]"
↑ ^2.0 ^2.1 "Developement of Metric for Measuring the Impact of RD&D Funding on GTO's Geothermal Exploration Goals"
↑ ^3.0 ^3.1 "[http://www.geo-energy.org/reports/Factors%20Affecting%20Cost%20of%20Geothermal%20Power%20Development%20-%20August%202005.pdf Factors Affecting Costs of Geothermal Power Development]"

[GEA-Development-1] "[http://www.geo-energy.org/reports/Factors%20Affecting%20Cost%20of%20Geothermal%20Power%20Development%20-%20August%202005.pdf Annual US Geothermal Power Production and Development Report]"

[Jenne_Cost_Time-2] 2.0 ^2.1 "Developement of Metric for Measuring the Impact of RD&D Funding on GTO's Geothermal Exploration Goals"

[GEA_Cost_Factors-3] 3.0 ^3.1 "[http://www.geo-energy.org/reports/Factors%20Affecting%20Cost%20of%20Geothermal%20Power%20Development%20-%20August%202005.pdf Factors Affecting Costs of Geothermal Power Development]"

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Geothermal/Exploration

From Open Energy Information