Stillwater Geothermal Area
Geothermal Area Profile
|Exploration Region:||Northwest Basin and Range Geothermal Region|
|GEA Development Phase:||Operational"Operational" is not in the list of possible values (Phase I - Resource Procurement and Identification, Phase II - Resource Exploration and Confirmation, Phase III - Permitting and Initial Development, Phase IV - Resource Production and Power Plant Construction) for this property.|
|Mean Reservoir Temp:||174°C447.15 K
|Estimated Reservoir Volume:||5.67 km³5,670,000,000 m³
|Mean Capacity:||47.2 MW47,200 kW
|USGS Mean Reservoir Temp:||160°C433.15 K
|USGS Estimated Reservoir Volume:||7 km³|||
|USGS Mean Capacity:||57 MW|||
History and Infrastructure
Operating Power Plants: 1
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Developing Power Projects: 0
|No geothermal projects listed.|
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Power Production Profile
|Gross Production Capacity:|
|Net Production Capacity:|
|Power Purchasers :|
Regulatory and Environmental Issues
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First Discovery Well
|Initial Flow Rate:||
|Flow Test Comment:|
Well Field Description
Well Field Information
|Number of Production Wells:|
|Number of Injection Wells:|
|Number of Replacement Wells:|
|Average Temperature of Geofluid:|| 160°C433.15 K
|Sanyal Classification (Wellhead):||Low Temperature|
|Reservoir Temp (Geothermometry):|
|Reservoir Temp (Measured):||204°C477.15 K
|Sanyal Classification (Reservoir):||Moderate Temperature|
|Depth to Top of Reservoir:||305m0.305 km
|Depth to Bottom of Reservoir:||915m0.915 km
|Average Depth to Reservoir:||610m0.61 km
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Geology of the Area
|Tectonic Setting:||Extensional Tectonics|
|Controlling Structure:||Accommodation Zone|
|Topographic Features:||Horst and Graben|
|Brophy Model:||Type E: Extensional Tectonic, Fault-Controlled Resource|
|Moeck-Beardsmore Play Type:||CV-3: Extensional Domain|
|Modern Geothermal Features:||Blind Geothermal System|
|Relict Geothermal Features:|
|Volcanic Age:||No volcanism|
|Host Rock Age:||Quaternary|
|Host Rock Lithology:||sandstone|
|Cap Rock Age:|
|Cap Rock Lithology:|
The Stillwater geothermal area is underlain by a section of poorly consolidated to unconsolidated fine-grained sediments of Quaternary age in which the bulk of Stillwater’s production occurs from a poorly consolidated sandstone referred to as the Production Sand. The sediments of Quaternary age overlie a section of poorly consolidated sedimentary rocks with interbedded basalt flows of Tertiary age. The Quaternary section consists mainly of clays, silts and some sands. The rocks in the Tertiary section consist mostly of fine grained sandstones, silty shales and soft clays. Within the Tertiary section there are discontinuous basalt flows up to 450 feet thick. Sedimentary units of both Quaternary and Tertiary ages were deposited in a lacustrine environment.
In the Stillwater production area the Production Sand is at a depth of 1,500 feet or less and has been silicified by deposition of silica from geothermal fluids. It is laterally extensive but overall has limited primary permeability. Permeability of the Production Sand in the area of the production and injection wells has been enhanced by fracturing along a fault zone which strikes roughly north-south. The fault zone also provides a vertical conduit which provides a small portion (probably less than 200 gpm) of deep recharge to the Production Sand in the immediate area of the production wells.
NEPA-Related Analyses (0)
Below is a list of NEPA-related analyses that have been conducted in the area - and logged on OpenEI. To add an additional NEPA-related analysis, see the NEPA Database.
CSV No NEPA-related documents listed.
Exploration Activities (0)
Below is a list of Exploration that have been conducted in the area - and cataloged on OpenEI. Add a new Exploration Activity
No exploration activities listed on OpenEI.
- Ruggero Bertani. 2005. World Geothermal Power Generation 2001-2005. Proceedings of World Geothermal Congress; Turkey: World Geothermal Congress.
- Geothermex Inc.. 2004. New Geothermal Site Identification and Qualification. Richmond, CA: California Energy Commission. Report No.: P500-04-051. Contract No.: 500-04-051.
- U.S. Geological Survey. 2008. Assessment of Moderate- and High-Temperature Geothermal Resources of the United States. USA: U.S. Geological Survey. Report No.: Fact Sheet 2008-3082.
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List of existing Geothermal Resource Areas.