Roosevelt Hot Springs Geothermal Area

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GEOTHERMAL ENERGYGeothermal Home
Roosevelt Hot Springs Geothermal Area




Area Overview



Geothermal Area Profile



Location: Milford, Utah

Exploration Region: Northern 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.

Coordinates: 38.4867158822°, -112.852795604°


Resource Estimate

Mean Reservoir Temp: 260°C533.15 K
500 °F
959.67 °R
[1]

Estimated Reservoir Volume: 16.3 km³16,300,000,000 m³
3.911 mi³
575,629,067,552.3 ft³
21,319,595,089.7 yd³
16,300,000,000,000 L
[2][3]

Mean Capacity: 34 MW34,000 kW
34,000,000 W
34,000,000,000 mW
0.034 GW
3.4e-5 TW
[4][5][6]

USGS Mean Reservoir Temp: 250°C523.15 K
482 °F
941.67 °R
[7]

USGS Estimated Reservoir Volume: 9 km³ [7]

USGS Mean Capacity: 120 MW [7]

Roosevelt Hot Springs Geothermal Area Location Map.

The Roosevelt Hot Springs Geothermal Area consists of 46.7 square miles located in Utah, approximately 19 km northeast of the town of Milford and about 265 km south of Salt Lake City. The Roosevelt Hot Springs Geothermal Area was first designated as a “known geothermal resource area” by the U.S. Geological Survey (USGS) in 1971 and had the first geothermal power generation unit approved by the Department of the Interior in April 1976.[8][9] The Blundell Geothermal Power Plant, initially completed in June 1984, is fueled by geothermal brines produced at the Roosevelt Hot Springs Geothermal Area with a nominal capacity of 26 MWe.[9][10] Interestingly, Blundell Unit 1 is the first commercially-producing geothermal power plant operating in the United States outside of the state of California. In fact, in 1984 the Blundell Unit 1 project was awarded the U.S. Department of Energy’s (DOE) innovation award for this feat.[1] Additional capacity of 11 MWe (gross) was brought online in 2007 with the addition of the Blundell Unit 2 binary plant.[10]


History and Infrastructure



Operating Power Plants: 2


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Developing Power Projects: 0

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Power Production Profile

Gross Production Capacity: 40 MW40,000 kW
40,000,000 W
40,000,000,000 mW
0.04 GW
4.0e-5 TW

Net Production Capacity:

Owners  :
  • PacificCorp Energy
  • PacificCorp

Power Purchasers :

Other Uses:


Figure 1. Schematic of Blundell Geothermal Power Plant Steam Unit 1 and Binary Unit 2.[4]

The hot springs in this area were exploited for commercial development as early as 1902. The earliest infrastructure at the hot springs was several bathhouses, a hotel, and a bathing pool.[8] Initially utilized by Native Americans, the popularity of these hot springs increased as miners, ranchers, and settlers frequented them. The development of the early railroad lines were influenced by the popularity of Utah’s hot springs, and the early railroads owned and operated hot springs resorts as an additional incentive for passengers to patronize their railway companies.[11] However, the hot springs reportedly dried up by 1966 and the foundations of the old buildings are all that remain of the original resort.[1]

The Roosevelt Hot Springs Geothermal Area spans 30,720 acres and the plant lies on 2,000 acres of U.S. Bureau of Land Management (BLM) land, 800 acres of Utah State School and Institutional Trust Lands Administration land, and 400 acres of privately owned land near Milford, Utah.[4] [10] Exploration activities began at Roosevelt Hot Springs Geothermal Area in the early 1970s, as summarized in the Exploration History portion of this case study. By 1975, the first production well, Well 3-1, was drilled to initiate the development of the 26 MWe gross single-stage flash geothermal power plant commissioned in 1984.[6]

In 1980, Phillips Petroleum was the primary leaseholder, with federal leases covering 70% of the Roosevelt Geothermal Area. The remaining Utah state land leases were held by Amax Exploration Inc., O’Brien Resources Corporation, and Thermal Power Company. Utah Power & Light and Phillips Petroleum established the first steam sales agreement for the Roosevelt Hot Springs Area in 1980.[12] The field operators through the years changed from Phillips Petroleum Company to Chevron Resources Company, California Energy Company, and PacifiCorp Energy. Utah Power & Light merged with PacifiCorp Company in 1989. PacifiCorp is the owner of the installed Harry Blundell Geothermal Power Plant and acquired the geothermal field in 2006. The Harry Blundell Power Plant is named after a former president of Utah Power & Light, which operates the station.[4] [5]

Power generation at Roosevelt began in 1981 with the installation of an experimental 1.6 MWe biphase turbine research unit, designed by Biphase Energy Systems.[1] Construction of the Blundell Power Plant Unit 1, a single-stage flash plant, began in 1982; the plant came online in 1984 and has been continuously operating since then.[10] The Blundell Unit 1 utilizes 2.25 million lbm/hour (1.0 million kg/hour) of geothermal fluids to produce 400,000 lbm/hour (180,000 kg/hr) of steam. In 1991, Utah Power initiated a 30-year steam purchase contract, and Blundell has produced an average of 167,000 MWh per annum (1991-2004). The Blundell Unit 1 plant is scheduled for retirement in 2021 based on the PacifiCorp steam purchase contract.[1]

In 2006, a binary geothermal power plant was constructed as an Ormat bottoming cycle to generate an additional 10 MWe net capacity; the plant became operational in 2007.[6] The working fluid for the binary plant is iso-pentane, with an inlet temperature of 176°C and an outlet temperature of 87°C at the heat exchanger. An air condenser cools the n-pentane, and acid injection is applied as a preventative measure against silica scaling.[10] The Blundell Unit 1 and Unit 2 plant schematic is shown in the Figure 1.

Roosevelt Hot Springs Timeline

Early use: Initial use of hot springs in the Roosevelt area by Native Americans, miners, rangers, and early settlers.[8]

1902: A Hotel, several bathhouses, and a bathing pool are built at Roosevelt Hot Springs.[8]

1966: Hot springs at Roosevelt “dry up,” and the original resort is abandoned.[1]

1968: E.N. Davie drills a few shallow holes near the main opal pit at Roosevelt Hot Springs. He hit steam at 84 m, which blew the drilling equipment out of the hole and continued to discharge for six weeks until the hole was finally cemented.[8]

1971: The Roosevelt Hot Springs area is noted as a “known geothermal resource area” by the U.S. Geological Survey.[8]

1972: Geothermal exploration activities begin at Roosevelt Hot Springs.[8]

1973: Temperature gradient drilling begins in the area to assess the geothermal resource.[13][9]

1975: Deeper exploration drilling in the area begins under Phillips Petroleum Company.[13][9]

1975: The first production well (Well 3-1) is drilled at Roosevelt Hot Springs in preparation for the siting of a 26 MWe single-flash geothermal power plant.[6]

1976: The U.S. Department of the Interior approves the first power generation unit at Roosevelt Hot Springs.[8][9]

1980: Phillips Petroleum Company is actively exploring the area for geothermal resources within a large lease holding covering 70% of the Roosevelt Geothermal Area. Other companies holding leases in the area include Amax Exploration Inc., O’Brien Resources Corporation, and Thermal Power Company.[12]

1980: Phillips Petroleum and Utah Power & Light establish the first steam sales agreement for the Roosevelt Hot Springs Area.[12]

1981: An experimental 1.6 MWe biphase turbine research unit designed by Biphase Energy Systems is successfully installed at the site.[1]

1982: Construction begins on the Blundell Power Plant Unit 1.[10]

1984: The 26 MWe Blundell Power Plant Unit 1 is completed at the site.[9][10]

1989: Utah Power & Light merges with PacifiCorp Company.[4]

1991: Utah Power begins a 30-year steam purchase contract with the Blundell Power Plant.[1]

2000: DOE funds a pilot test project of the Kalina Cycle binary heat recovery unit by POWER Engineers, Inc. at Roosevelt Hot Springs.[14]

2006: PacifiCorp gains ownership of the installed Harry Blundell Geothermal Power Plant.[4]

2007: The power generation capacity of the facility is expanded by 11 MWe with the addition of the Blundell Unit 2 binary plant, which uses an Ormat bottoming cycle to produce additional power.[10] [6]


Regulatory and Environmental Issues


In order to mitigate the potential noise emissions such as truck traffic, drilling activities, and steam venting at Roosevelt Hot Springs Geothermal Area, an environmental noise assessment was conducted. The study concluded that liquid-dominated fields such as Roosevelt Hot Springs do not present a material environmental noise emission disturbance.[15]

Future Plans


In 2008, PacifiCorp proposed a possible capacity expansion with a Blundell Unit 3 dual flash design. PacifiCorp has a 2,000 MW renewable energy commitment and was interested in increasing its renewable baseload generation at Roosevelt Hot Springs. The location, infrastructural needs, and plant design were discussed, and a rig test was conducted in April 2008, which yielded positive results.[10] However, Unit 3 was not constructed.

The drilling of two test wells in 2008 indicated the extent of the reservoir was greater than reflected in the existing geological conceptual models. Future development options include the utilization of these two test wells as production wells or the direct tapping of the steam zone in the reservoir.[6]

Exploration History



First Discovery Well

Completion Date:

Well Name: Well No. 3-1

Location:

Depth: [12][6]

Initial Flow Rate: 78 kg/s4,680 kg/min
280,800 kg/hour
6,739,200 kg/day
78 L/s
1,236.325 gal/min
[12]

Flow Test Comment: Steam-to-water ratio of 0.17 [12]

Initial Temperature: 260°C533.15 K
500 °F
959.67 °R
[12]


Figure 2. Pre-production seismicity overlain on Roosevelt Hot Springs geologic map.[16][9]

Drilling first occurred at the Roosevelt Hot Springs Geothermal Area in 1968, when E.N. Davie drilled a few shallow holes in the vicinity of the main opal pit. At a depth of 84 m, steam blew the drilling equipment out of the hole and the uncontrolled discharge occurred for a six-week duration, at which point the hole was cemented. The temperature of the steam was 270°C, increasing with continued discharge. However, wellhead pressure measurements and condensate analyses were not performed. Additionally, at another shallow drill hole at the opal pit of approximately 24 m depth, boiling water was audible at the surface.[8]

Geothermal exploration activities began at Roosevelt Hot Springs in September 1972.[8] Numerous geoscience investigations have been carried out in the decades since the early 1970s--not only for characterization of the geothermal resource itself, but also as a testing ground for innovative resource assessment methods.[1] Temperature gradient hole drilling was initiated in 1973, with deeper exploration drilling performed in 1975 by Phillips Petroleum Co., confirming the existence of a 260°C hydrothermal resource.[13][9] This led to the Roosevelt Hot Springs Unit approval by the U.S. Department of the Interior.[9]

The following geophysical exploration surveys were performed prior to 1978. Microearthquake seismic studies indicated a low velocity zone underlying the Mineral Mountains, but with limited resolution in constraining the specific geometry of the low velocity body. Gravity and magnetic surveys were applied to understand the structure and depth of the alluvial fill in the valley, but neither technique identified an igneous intrusion heat source. Thermal gradient holes were drilled at a depth of 30-60 m with a maximum recorded temperature gradient of 960°C/km, constraining the thermal field to a 6 by 12-km areal extent. Resistivity surveys as well as heat flow measurements identified anomalies coincident to the fault system in the geothermal area. The magnetotelluric observations were largely inconclusive at the time due to ambiguity and numerous interpretations of the highly anomalous data, resulting from the effects of near-surface 3D inhomogeneities in the survey area. Research prior to 1978 identified the locations of fracture systems and possible conduits for geothermal fluid flow to the surface, but did not yet constrain the proposed igneous heat source of the geothermal system.[13]

Continued geophysical activities undertaken from 1978 to 1991 provided additional insights to the understanding of the Roosevelt Geothermal System, specifically in relation to the heat source. The gravity model was refined by Becker in 1985[17], revealing an anomalous gravity low at a 3,962-6,096 m depth beneath the geothermal reservoir.[17] These results coincide with Robinson and Iyer’s 1981[18] study of the P-wave structure in the vicinity of Roosevelt Hot Springs.[18] In this study, a low velocity zone was detected from the upper mantle to approximately 4,877 m beneath the western side of the Mineral Mountains. Additionally, pre-production microseismic studies indicated the Negro Mag graben system remains active, as shown in Figure 2. The focal depths of the seismicity were located within two main zones, at 3,048 m and at 7,925 m below the surface, with an aseismic region in between.[9]

Well testing performed by 1991 indicated a highly fractured reservoir based on the ability of the production wells to flow in a range from 300 klbm/hour to 1,000 klbm/hour; the injection capacity was determined at a rate of 1,850 klbm/hour. Heat flow data show a primary reservoir dimension of 3,048 m by 7,010 m, and the fluid volume within the reservoir is estimated at 3.3-8 billion barrels based on flow test measurements.[9][3] The pre-exploitation reservoir pressure was measured at 1,365 psia at a depth of 899 m.[9] This continued seismic activity along the Negro Mag graben system may be partially attributable to the level of permeability observed at the intensively fractured geothermal reservoir.[19]


Well Field Description



Well Field Information

Development Area: 30,720


Number of Production Wells: 4 [20][2][6]

Number of Injection Wells: 3 [20][6]

Number of Replacement Wells: 2 [3][6]


Average Temperature of Geofluid: 340 227°C500.15 K
440.6 °F
900.27 °R
[1]

Sanyal Classification (Wellhead): Moderate Temperature


Reservoir Temp (Geothermometry): 286°C559.15 K
546.8 °F
1,006.47 °R

Reservoir Temp (Measured):

Sanyal Classification (Reservoir): High Temperature


Depth to Top of Reservoir: 382 m0.382 km
0.237 mi
1,253.281 ft
417.759 yd
[1][10]

Depth to Bottom of Reservoir: 2231 m2.231 km
1.386 mi
7,319.554 ft
2,439.844 yd
[1][10]

Average Depth to Reservoir: 1307 m1.307 km
0.812 mi
4,288.058 ft
1,429.348 yd
[10]


Figure 3. Roosevelt Hot Springs Geothermal Area map and original temperature contours.[6]

The 2009 Roosevelt Hot Springs orthophoto (Figure 3) delineates the location of the injection wells, production wells, and other deep exploration wells. The original temperature distribution of the Roosevelt Geothermal Field is shown by contours at 1,500-1,800 m depth overlain on the orthophoto map. The location of the critical permeability structures, the Opal Mound Fault Zone, and the Negro Mag cross-fault are also indicated.[6]

There are four production wells (wells 54-3, 45-3, 28-3, and 13-10) and three injection wells (wells 14-2, 12-35, and 82-33). The primary injector is well 14-2, with the highest recorded temperature in the field of 268°C at a depth of 1,858 m; this well constitutes approximately 70% of overall injection. Additionally, two exploration wells (58-3 and 71-10) were drilled in 2008 with recorded temperatures of 261°C below 1,500 m depth. Either of these wells are posited as adequate producers or injectors for purposes of further field expansion.[6] The steam gathering system consists of 7.2 km of brine piping and 1.6 km of steam piping.[1]


Research and Development Activities


An R&D project funded by DOE in 2000 enabled pilot testing of the Kalina Cycle binary heat recovery unit to be applied to the Roosevelt Hot Springs by POWER Engineers, Inc. The project objective was heat recovery from a 171°C silica-rich geothermal brine to be added as a bottoming cycle at the Blundell Geothermal Power Plant. Running silica-rich brines through a low temperature heat exchanger presents scaling risk as the silica precipitates from solution with decreased temperature. POWER Engineers, Inc. proposed to determine the adequate pH modification and optimal heat exchanger materials to apply the Kalina Cycle unit at Roosevelt Hot Springs Geothermal Area. The model outcome from the study indicated that a 13 MW bottoming Kalina Cycle Unit, as well as an additional 15 MW of topping capacity, can be feasibly installed at Roosevelt Hot Springs Geothermal Area.[14]


Technical Problems and Solutions


The 1.6 MW biphase turbine-generator set was only run for less than a year starting in 1981. As a result of this test, a flash-steam plant was favored over the biphase unit for the permanent installation. The main reason for not selecting the biphase unit, even though it could produce 25% more power as compared to the flash steam type, was reportedly due to the complicated mechanical operation of the plant and the related high maintenance that it required.

Some silica scaling from the approximately 230 ppm was originally experienced from the brine, thus acid injection was started to control the scaling.

Regular maintenance has been performed on the Blundell Plant, such as the new turbine rotor installed in May 2001 to increase plant efficiency.[1]


Geology of the Area



Geologic Setting

Tectonic Setting: Extensional Tectonics [9]

Controlling Structure: [9]

Topographic Features: [9]

Brophy Model: Type E: Extensional Tectonic, Fault-Controlled Resource [9]

Moeck-Beardsmore Play Type: CV-2a: Plutonic - Recent or Active Volcanism, CV-2b: Plutonic - Inactive Volcanism, CV-3: Extensional Domain"CV-2a: Plutonic - Recent or Active Volcanism, CV-2b: Plutonic - Inactive Volcanism, CV-3: Extensional Domain" is not in the list of possible values (CV-1a: Magmatic - Extrusive, CV-1b: Magmatic - Intrusive, CV-2a: Plutonic - Recent or Active Volcanism, CV-2b: Plutonic - Inactive Volcanism, CV-3: Extensional Domain, CD-1: Intracratonic Basin, CD-2: Orogenic Belt, CD-3: Crystalline Rock - Basement) for this property.


Geologic Features

Modern Geothermal Features: Fumaroles, Hot Springs [1][21]

Relict Geothermal Features: Other Hydrothermal Deposits, Silica Deposition [19][22]

Volcanic Age: Piacenzian [19]

Host Rock Age: 1- Tertiary; 2- Precambrian [1]

Host Rock Lithology: 1- granite; 2- metamorphic [1]

Cap Rock Age:

Cap Rock Lithology:


Figure 4. Roosevelt Hot Springs Geothermal Area geological map.[13]

The Roosevelt Hot Springs Geothermal Area is located in the vicinity of the transition between the Basin and Range physiographic province and the Colorado Plateau, at the eastern margin of the Basin and Range. Specifically, the geothermal area is situated at the eastern side of the Milford (a.k.a. Escalante) Valley and to the west of the batholith of the Mineral Mountains. The Mineral Mountains, the first mountain range west of Utah’s Wasatch Front, are a N-S trending granitic intrusive complex spanning 32 km in length and 8 km in width that constitute the majority of the consolidated rock outcrop in the Roosevelt area (Figure 4).[8][13] The Mineral Mountains’ pluton ranges in age from the Oligocene to the early Pliocene. The oldest phase of magmatic activity occurred at about 25 Ma with an intrusion into Precambrian rocks and a subsequent intrusion around 22 Ma by the primary intrusive complex. An additional igneous sequence was emplaced between 9.0 and 9.6 Ma. The most recent volcanic episode occurred at approximately 2.7 Ma in the Twin Peaks Volcanic Complex, which is characterized by basalt flows and the eruption of rhyolite domes. The final rhyolitic volcanism was initiated between 0.8 and 0.5 Ma, producing additional rhyolite tuffs, flows, and domes to the west of the Mineral Mountains within 5 km of the geothermal area. Chemical signature analyses of the rhyolitic domes indicate origination from the same parent magma source.[9] The majority of the Roosevelt area is covered by thick Tertiary- and Quaternary-age alluvial deposits from the Mineral Mountain Range with a maximum alluvial fill of 1,676 m at the eastern margin of the Milford Valley.[8]

Two silicic flow units have been identified as the Negro Mag Wash Unit and the Wildhorse Canyon Unit. The Negro Mag Wash Unit is a late Pliocene unit, approximately 60 m thick, consisting of two flows of dense, welded black glass overlain by light grey, porous rock that was likely deposited as a pumice flow; perlite is mined from this rock unit. The Wildhorse Canyon Unit is also a Pliocene unit, approximately 120 m in thickness, comprised of two flows that exhibit gradation from obsidian at the base to greyish-tan glassy rock at the upper portion of the flow.[8] The stratigraphic units in the Milford Valley consist of 1,000 m of lacustrine clastics, 1,100 m of Cenozoic sands, 300 m of volcanics, and 700 m of Cenozoic conglomerate overlaying quartz monzonite as well as Precambrian metamorphics.[19]

The Roosevelt Hot Springs Geothermal Area is a hydrothermal reservoir that is structurally dominated by a fault intersection.[23][24] Two predominant structural features constrain the reservoir (i.e., the Opal Mound Fault and the Negro Mag Fault). The Opal Mound Fault, also referred to as the Dome Fault, is a conspicuous eastward-dipping, normal fault trending N-NE, with a fault trace approximately 4 km in length.[24] The Opal Mound Fault is the boundary between a graben to the east and a narrow horst structure to the west. The west block of this fault has an offset of greater than 6 m near the gently domed siliceous deposits, the namesake of the Dome/Opal Mound Fault. The Opal Mound Fault was formed no later than the Pleistocene, as evidenced by the fault’s disruption of the alluvial valley fill as well as by the fault scarp’s indication of through-going drainages.[8] Its fault trace is denoted by siliceous deposition, opaline deposition, surface alteration, and alluvial scarps.[9] These siliceous sinter deposits indicate the presence of a hydrothermal system and are generated due to boiling acid-sulfate waters.[13]

Moreover, an east-striking fault was identified in the Negro Mag Wash, overlain by alluvium in the Roosevelt area.[8] The Negro Mag Fault, also known as the Hot Springs Fault, is a high-angle, oblique slip characterized by substantial right lateral shear faulting. This primary regional structural control is seismically active into the deep basement and is coincident to the axis of a graben structure spanning four miles in length. The graben is the boundary between the Pleistocene rhyolite dome complex to the south and the dissected ground to the north that is lacking in any rhyolite domes.[9] Fault movement on the Negro Mag Wash Fault predates the Opal Mound Fault as well as the silicic flows in the Negro Mag Wash,[8] with an approximate age of at least the early Pleistocene.[9]

Further, numerous small-scale faults have been identified throughout the Mineral Mountains. These small-scale faults are approximated to be Pleistocene to Holocene age, occurring after the Opal Mound faulting but predating 0.5 Ma. The frequency of occurrence of the low-angle (5°-35°) denudation faults is greater within the Roosevelt Geothermal Area and the maximum estimated depth of formation is 4,877 m.[9][8] These low-angle faults in the vicinity of the dominant fault structures may provide permeable conduits for geothermal fluid flow.[24]

Surface alteration is present in the Roosevelt Hot Springs Geothermal Area due to rock-fluid interaction as well as mineral precipitation from the geothermal brine. Three rock units (Unit A, Unit B, and Unit C) consisting of alluvium were cemented as a result of hydrothermal alteration at the rock-fluid interface of upwelling geothermal fluids. A successive alteration gradation occurs within 60 m of the surface from opal and alunite to alunite-kaolinite, alunite-kaolinite-montmorillonite, and muscovite-pyrite.[13] Also, siliceous hot spring deposits exist in the vicinity of the Opal Mound and Negro Mag Wash Faults. Additional surface alteration in the form of red, hematite-stained patches of alluvium is interpreted to be related to prior surface manifestations, such as hot springs or seeps.[8]


Hydrothermal System


Figure 5. Roosevelt Hot Springs Geothermal Area surface conductive heat flow measurements.[24]

The earliest recorded scientific study of Roosevelt Hot Springs was conducted in 1908 by Willis T. Lee[25] within a USGS water resources study of the Beaver Valley, Utah. At the time, Lee mentioned two names for the hot springs, Roosevelt and McKeans Hot Springs, but “Roosevelt” was the adopted name for this surface manifestation of the geothermal system. The recorded flow of one of the hot springs in 1908 was 38 l/min with a temperature of 88°C, although the total number of hot springs was not recorded.[8] Measurements in 1950 produced a 4 l/min flow rate from the springs at a temperature of 85°C, and by 1957 the flow from the springs was minimal, with a recorded temperature of 55°C. By 1966 the springs had dried up, as corroborated by a Utah Geological and Mineral Survey study that year, as well as observations from 1972-1973.[8] This is attributed to two potential explanations: either silica deposition sealed permeable pathways to the surface springs, or the groundwater table in the Escalante Valley lowered and impacted groundwater flow patterns. The hydraulic connection of Roosevelt Hot Springs to the shallow groundwater table was not constrained in order to confirm the latter hypothesis.[8]

The geothermal reservoir is structurally dominated by the Negro Mag and Opal Mound Faults.[9] Surface conductive heat flow measurements indicate an elongated heat flow anomaly coincident to the Opal Mound fault trace, shown in Figure 5.[24] The regional heat flow was measured at 92 mW/m2 while the local heat flow above the geothermal reservoir was greater than 1000 mW/m2. An eastward extension of heat flow along the Negro Mag Fault was determined through downward continuation of the heat flow data. The plume to the northwest of the fault intersection of the Negro Mag and the Opal Mound Faults is related to the outflow zone of the geothermal reservoir.[9]

Studies have been conducted in order to determine the age of the hydrothermal system based on paleomagnetic dating of opal, as well as hydration dating of obsidian. The results yielded great uncertainty and thus the age of the hydrothermal system remains unconstrained.[9]


Heat Source


Figure 6. Roosevelt Hot Springs geological conceptual model proposing a magma chamber heat source at depth.[9]

The Roosevelt Hot Springs geothermal reservoir may be characterized as a dynamic flow system contained within an intensively fractured graben.[9] The Negro Mag Fault zone enables meteoric waters from the Mineral Mountains to circulate to depth through its fracture network, with active faulting zones potentially providing open fractures at distinct depths of 3,048 and 7,925 m. The meteoric waters are heated up within the fractures and flow down the hydrological gradient to Milford Valley. The intersection of the primary structures in the geothermal area--the Opal Mound Fault and the Negro Mag Fault--provides a fracture network for upwelling geothermal fluids and a permeable three-dimensional structure for the geothermal reservoir.

The proposed heat source for the Roosevelt geothermal area is a plume of partial melt material underlying the central to western Mineral Mountains, as shown in the conceptual model in Figure 6.[9] Due to the microseismic evidence of an impermeable layer between 3,048 and 7,925 m, a deeper and hotter resource may exist beneath the known geothermal reservoir, with connectivity of the two systems at the deep normal faults in the region. Although this connectivity is not confirmed, the possibility exists for Roosevelt Hot Springs as well as for other geothermal reservoirs such as The Geysers, Dixie Valley, and Valles Caldera.[9]


Geofluid Geochemistry



Geochemistry

Salinity (low): 6444 [1]

Salinity (high): 6614 [1]

Salinity (average): 6529 [1]

Brine Constituents: Sodium chloride water, near neutral pH, of meteoric origin [22][9][23]

Water Resistivity:


Figure 7. Chemical composition of geothermal fluids from the Roosevelt Hot Springs Geothermal Reservoir.[1]

Geochemical analyses showed dilute sodium chloride brines grading into acid sulfate waters at depth. Na-K-Ca and SiO2 geothermometers indicated a deep reservoir temperature of 241°C and 286°C for the seep and deep well fluid samples, respectively; these are among the greatest calculated subsurface temperatures in the state of Utah.[13] Fluid sampling indicates a common reservoir source for the wells and seeps in the Roosevelt Hot Springs area--after taking into account the effects of mixing with shallow groundwater.[9] Oxygen isotope analysis indicates the likely source of the fluids for the geothermal system is meteoric recharge originating from the Mineral Mountains.[24] Stable isotope studies suggest the geothermal fluids have an approximate age of 10,000 to 15,000 years.[9]

The chemical composition of the geothermal fluids sampled from two wells, Well 14-2 and Well 72-16, are shown in Figure 7.[1]




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 (43)


Below is a list of Exploration that have been conducted in the area - and cataloged on OpenEI. Add.png Add a new Exploration Activity


Page Technique Activity Start Date Activity End Date Reference Material
Aerial Photography At Roosevelt Hot Springs Geothermal Area (Petersen, 1975) Aerial Photography 1975 1975


Aerial Photography At Roosevelt Hot Springs Geothermal Area (Ward, Et Al., 1978) Aerial Photography 1978 1978


Aeromagnetic Survey At Roosevelt Hot Springs Geothermal Area (Faulder, 1991) Aeromagnetic Survey 1991 1991


Aeromagnetic Survey At Roosevelt Hot Springs Geothermal Area (Ward, Et Al., 1978) Aeromagnetic Survey 1978 1978


Audio-Magnetotellurics At Roosevelt Hot Springs Geothermal Area (Ward, Et Al., 1978) Audio-Magnetotellurics 1978 1978


Compound and Elemental Analysis At Roosevelt Hot Springs Area (Christensen, Et Al., 1983) Compound and Elemental Analysis


Controlled Source Audio MT At Roosevelt Hot Springs Area (Combs 2006) Controlled Source Audio MT


Cuttings Analysis At Roosevelt Hot Springs Area (Christensen, Et Al., 1983) Cuttings Analysis


Cuttings Analysis At Roosevelt Hot Springs Geothermal Area (1976) Cuttings Analysis 1976 1976


DC Resistivity Survey (Mise-A-La-Masse) At Roosevelt Hot Springs Geothermal Area (Ward, Et Al., 1978) DC Resistivity Survey (Mise-A-La-Masse) 1978 1978


DC Resistivity Survey (Schlumberger Array) At Roosevelt Hot Springs Geothermal Area (Ward, Et Al., 1978) DC Resistivity Survey (Schlumberger Array) 1978 1978


Exploratory Well At Roosevelt Hot Springs Geothermal Area (Faulder, 1991) Exploratory Well 1991 1991


Exploratory Well At Roosevelt Hot Springs Geothermal Area (Petersen, 1975) Exploratory Well 1968 1968


Field Mapping At Roosevelt Hot Springs Geothermal Area (Petersen, 1975) Field Mapping 1975 1975


Field Mapping At Roosevelt Hot Springs Geothermal Area (Ward, Et Al., 1978) Field Mapping 1978 1978


Flow Test At Roosevelt Hot Springs Geothermal Area (Faulder, 1991) Flow Test 1984 1984


Flow Test At Roosevelt Hot Springs Geothermal Area (Faulder, 1994) Flow Test 1994 1994


Geothermal Literature Review At Roosevelt Hot Springs Geothermal Area (Faulder, 1991) Geothermal Literature Review 1991 1991


Geothermal Literature Review At Roosevelt Hot Springs Geothermal Area (Petersen, 1975) Geothermal Literature Review 1975 1975


Geothermal Literature Review At Roosevelt Hot Springs Geothermal Area (Ward, Et Al., 1978) Geothermal Literature Review 1978 1978


Geothermometry At Roosevelt Hot Springs Geothermal Area (Faulder, 1991) Geothermometry 1982 1982


Geothermometry At Roosevelt Hot Springs Geothermal Area (Petersen, 1975) Geothermometry 1975 1975


Geothermometry At Roosevelt Hot Springs Geothermal Area (Ward, Et Al., 1978) Geothermometry 1978 1978


Ground Gravity Survey At Roosevelt Hot Springs Geothermal Area (Faulder, 1991) Ground Gravity Survey 1985 1985


Ground Gravity Survey At Roosevelt Hot Springs Geothermal Area (Ward, Et Al., 1978) Ground Gravity Survey 1978 1978


Ground Magnetics At Roosevelt Hot Springs Geothermal Area (Ward, Et Al., 1978) Ground Magnetics 1978 1978


Isotopic Analysis- Fluid At Roosevelt Hot Springs Geothermal Area (Faulder, 1991) Isotopic Analysis- Fluid 1981 1981


Isotopic Analysis- Fluid At Roosevelt Hot Springs Geothermal Area (Ward, Et Al., 1978) Isotopic Analysis- Fluid 1978 1978


Magnetotellurics At Roosevelt Hot Springs Geothermal Area (Ward, Et Al., 1978) Magnetotellurics 1978 1978


Micro-Earthquake At Roosevelt Hot Springs Geothermal Area (Faulder, 1991) Micro-Earthquake 1991 1991


Micro-Earthquake At Roosevelt Hot Springs Geothermal Area (Ward, Et Al., 1978) Micro-Earthquake 1978 1978


Micro-Earthquake At Roosevelt Hot Springs Geothermal Area (Zandt, Et Al., 1982) Micro-Earthquake 1982 1982


Paleomagnetic Measurements At Roosevelt Hot Springs Geothermal Area (Faulder, 1991) Paleomagnetic Measurements 1977 1977


Paleomagnetic Measurements At Roosevelt Hot Springs Geothermal Area (Ward, Et Al., 1978) Paleomagnetic Measurements 1978 1978


Petrography Analysis At Roosevelt Hot Springs Geothermal Area (Petersen, 1975) Petrography Analysis 1975 1975


Pressure Temperature Log At Roosevelt Hot Springs Geothermal Area (Faulder, 1991) Pressure Temperature Log 1979 1979


Radiometrics At Roosevelt Hot Springs Geothermal Area (Petersen, 1975) Radiometrics 1975 1975


Refraction Survey At Roosevelt Hot Springs Geothermal Area (Ward, Et Al., 1978) Refraction Survey 1978 1978


Rock Sampling At Roosevelt Hot Springs Geothermal Area (Faulder, 1991) Rock Sampling 1977 1977


Rock Sampling At Roosevelt Hot Springs Geothermal Area (Ward, Et Al., 1978) Rock Sampling 1978 1978


Self Potential At Roosevelt Hot Springs Geothermal Area (Ward, Et Al., 1978) Self Potential 1978 1978


Thermal Gradient Holes At Roosevelt Hot Springs Geothermal Area (Ward, Et Al., 1978) Thermal Gradient Holes 1978 1978


Water Sampling At Roosevelt Hot Springs Geothermal Area (Faulder, 1991) Water Sampling 1982 1987

References


  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 Andrew Chiasson. 2004. Electric Power Generation in the Roosevelt Hot Springs Area-the Blundell Geothermal Power Plant. GRC Bulletin. 16 - 20.
  2. 2.0 2.1 E. Yearsley. 1994. Roosevelt Hot Springs Reservoir Model Applied to Forecasting Remaining Field Potential. GRC Transactions. 18:617-622.
  3. 3.0 3.1 3.2 D. D. Faulder. 1994. Long-Term Flow Test No. 1, Roosevelt Hot Springs, Utah. US Government Documents (Utah Regional Depository). 589.
  4. 4.0 4.1 4.2 4.3 4.4 4.5 PacifiCorp Energy. 2011. Blundell Plant Fact Sheet. PacifiCorp Website: PacifiCorp Energy.
  5. 5.0 5.1 Utah Geological Survey. Geothermal Use, Power Plants - Utah Geological Survey [Internet]. 2013. [updated 2013;cited 09/17/2013]. Available from: http://geology.utah.gov/emp/geothermal/powerplants.htm
  6. 6.00 6.01 6.02 6.03 6.04 6.05 6.06 6.07 6.08 6.09 6.10 6.11 6.12 R. Allis,G. Larsen. 2012. Roosevelt Hot Springs Geothermal Field, Utah - Reservoir Response After More Than 25 Years of Power Production. In: Thirty-Seventh Workshop on Geothermal Reservoir Engineering; 32202/01/01; Stanford, CA. Stanford, CA: Stanford University; p. 8
  7. 7.0 7.1 7.2 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.
  8. 8.00 8.01 8.02 8.03 8.04 8.05 8.06 8.07 8.08 8.09 8.10 8.11 8.12 8.13 8.14 8.15 8.16 8.17 8.18 8.19 8.20 Geology and Geothermal Potential of the Roosevelt Hot Springs Area, Beaver County, Utah
  9. 9.00 9.01 9.02 9.03 9.04 9.05 9.06 9.07 9.08 9.09 9.10 9.11 9.12 9.13 9.14 9.15 9.16 9.17 9.18 9.19 9.20 9.21 9.22 9.23 9.24 9.25 9.26 9.27 9.28 9.29 9.30 D. D. Faulder. 1991. Conceptual Geologic Model and Native State Model of the Roosevelt Hot Springs Hydrothermal System. In: Proceedings of the Sixteenth Workshop on Geothermal Reservoir Engineering. Sixteenth Workshop on Geothermal Reservoir Engineering; 1991/01/01; Stanford, California. Stanford, California: Stanford University; p. 131-142
  10. 10.00 10.01 10.02 10.03 10.04 10.05 10.06 10.07 10.08 10.09 10.10 10.11 Garth Larsen, Mike Saunders. 04/2008. Presentation: Blundell Geothermal Power Plant. Utah Geological Survey website. PacifiCorp Energy. 32p.
  11. NREL. Geothermal Technologies Program Utah [Internet]. 2005. [updated 06/2005;cited 09/13/2013]. Available from: http://www.nrel.gov/docs/fy05osti/36552.pdf
  12. 12.0 12.1 12.2 12.3 12.4 12.5 12.6 J.L. Rasband. 1981. Summary of Utah Power and Light Company Geothermal Activities. In: Proceedings of the Fifth Annual Geothermal Conference and Workshop. Fifth Annual Geothermal Conference and Workshop; 1981/06/23; San Diego, California. Stanford, California: Stanford University; p. 3-18
  13. 13.0 13.1 13.2 13.3 13.4 13.5 13.6 13.7 13.8 S. H. Ward,W. T. Parry,W. P. Nash,W. R. Sill,K. L. Cook,R. B. Smith,D. S. Chapman,F. H. Brown,J. A. Whelan,J. R. Bowman. 1978. A Summary of the Geology, Geochemistry, and Geophysics of the Roosevelt Hot Springs Thermal Area, Utah. Geophysics. 43(7):1515-1542.
  14. 14.0 14.1 W.E. Lewis, M. Ralph. 2002. A DOE-Funded Design Study for Pioneer Baseload Application Of an Advanced Geothermal binary Cycle at a Utility Plant in Western Utah. In: GRC Transactions. GRC Annual Meeting; 2002/09/22; Reno, Nevada. Davis, California: Geothermal Resources Council; p. 695-699
  15. Philip Leitner. 1978. An Overview of Environmental Issues: Roosevelt Hot Springs KGRA, Utah: Geothermal Noise Effects. DOE Science and Technical Information. unknown.
  16. D. L. Nielson. 1989. Stress in Geothermal Systems. In: GRC Transactions. GRC Annual Meeting; 1989/10/01; Santa Rosa, California. Davis, California: Geothermal Resources Council; p. 271-276
  17. 17.0 17.1 D. J. Becker. 1985. Modelling of the Hydrothermal System, Mineral Mountains Vicinity, Utah [Thesis]. [Dallas, TX]: Southern Methodist University.
  18. 18.0 18.1 R. Robinson,H. M. Iyer. 1981. Declination of a Low-Velocity Body Under the Roosevelt Hot Springs Geothermal Area, Utah, Using Teleseismic P-Wave Data. Geophysics. 46(10):1456-1466.
  19. 19.0 19.1 19.2 19.3 D. J. Becker, D. D. Blackwell. 1993. A Hydrothermal Model of the Roosevelt Hot Springs Area, Utah, USA. In: Proceedings of the 15th New Zealand Geothermal Workshop. 15th New Zealand Geothermal Workshop; 1993/01/01; unknown. unknown: unknown; p. 247-252
  20. 20.0 20.1 M.J. Kerna, T.S. Allen. 1984. Roosevelt Hot Springs Unit Development: A Case History. In: GRC Transactions. GRC Annual Meeting; 1984/08/26; Reno, Nevada. Davis, California: Geothermal Resources Council; p. 75-77
  21. Roosevelt Hot Springs Geothermal System, Utah - Case Study
  22. 22.0 22.1 A Review of High-Temperature Geothermal Developments in the Northern Basin and Range Province
  23. 23.0 23.1 Trace Element Geochemical Zoning in the Roosevelt Hot Springs Thermal Area, Utah
  24. 24.0 24.1 24.2 24.3 24.4 24.5 Thermal Studies in a Geothermal Area.pdf
  25. Water Resources of Beaver Valley, Utah


List of existing Geothermal Resource Areas.






Some of the content on this page was part of a case study conducted by: NREL Interns


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