Rye Patch, Humboldt, or Humboldt House, 50 km north of Lovelock, was founded in 1868 as an eating station along the Central Pacific Railroad. The Rye Patch geothermal area is located in the Humboldt River valley west of a major north-striking range-front fault that bounds the Humboldt Range. No thermal springs are known from the area, but Pleistocene(?) sinter crops out nearby. These siliceous and calcareous spring deposits occur as low domes in two areas to the south and to the west of Humboldt House. These hot-spring deposits contain sulfur, gypsum, and detectable amounts of mercury (Russell, 1885, p. 54, 55; Vanderburg, 1936, p. 17; Bailey and Phoenix, 1944, p. 107). One locality is in SW¼ SE¼ Sec. 33, T32N, R33E, and consists of a sinter mound about 305 by 213 m. The second locality occurs in an area of Quaternary sandstone in NW¼ SW¼ Sec. 32, T32N, R33E, and is about 150 m in diameter (Olcott and Spruck, 1961). MacKnight and others (2005) identified more extensive areas of spring deposits and correlated them with concealed fauls west of and parallel to the main Humboldt Range fault. The area of spring deposits is about 1.6 km west of this major fault, which separates Mesozoic rocks and surficial deposits. Audiomagnetotelluric data for the area is available in Long and Batzle (1976c). A warm spring was reported in the site of Rye Patch (Sec. 20, T30N, R33E) by Crofutt (1872), but it has not been recognized in any more recent studies. Hot water (75.6°C) flows from an old mineral exploration drill hole in SE¼ Sec. 32, T32N, R33E. Geothermometry on this fluid led Phillips Petroleum Co. to explore the area (W.L. Desormier in Lane, 1979). Phillips Petroleum Co. drilled a 565-m-deep geothermal test in SE¼ Sec. 21, T31N, R33E in 1977. Temperatures up to 163°C were reported. Temperatures as high as 204°C were reported in later wells, and geothermometers suggest a resource temperature of at least 243°C (Ehni and Ellis, 2002).
Geothermal drilling at Rye Patch in the late 1980s and early 1990s resulted in one successful well; other wells were too cold or had no fluid flow (Feigner and others, 1999). Mt. Wheeler Power recently sold the project to Presco Energy LLC of Englewood, CO. The U.S. Department of Energy has agreed to provide funding ($1.62 million) to study and help define the resource at Rye Patch (www.eren.doe.gov/geothermal/). Additional funding was awarded in late 2002 to the University of Nevada, Reno to work cooperatively with Presco Energy and the adjacent land owner, Florida Canyon Mine, to conduct research at the site and drill some test wells to expand the resource on to the Florida Canyon Mine property. Wells at the Florida Canyon Mine (about 175 m deep) in NW¼ Sec. 3, T31N, R33E produce fluids at about 100°C. In the late 1980s, these fluids were circulated through heat exchangers to heat process fluids for the heap leaching operation.
Between May and July 2003, the Great Basin Center for Geothermal Energy at the University of Nevada, Reno (UNR) successfully drilled and completed five research wells (drilling report) located near the Florida Canyon Mine (map). These wells were funded by the U.S. Department of Energy grant to UNR in collaboration with Presco Energy and Apollo Gold (Project update). All wells were completed as temperature gradient wells at the following depths: one well to 500 feet, three wells to 1000 feet, and one well to 1500 feet. A total of 1850 feet of core was obtained from three wells.
As of February 2004, the five wells were being monitored for temperature (Humboldt House logs, Humboldt House graph, Rye Patch graph), and the cores were being studied using geochemical and petrographic techniques at the University of Nevada, Reno.
Triassic rocks are encountered below several hundred meters of Tertiary sedimentary and volcanic rocks (including sinter?). A sandstone and siltstone unit, at about 1,000-m depth, was intersected within the predominantly carbonate-rock section of the Triassic Natchez Pass Formation. The sandstone and siltstone unit is apparently the productive part of the stratigraphic interval; faults may control fluid migration in the reservoir (Feighner and others, 1999). Also, carbonate rocks of the Natchez Pass Formation were found to be productive in a well deepened to 643 m in 2002; reservoir temperatures were reported to be about 150°C (U.S. Department of Energy, in Geothermal Resources Council Bulletin, v. 31, no.4). Geophysical data for the area are reported by Duffrin and others (1985) and Schaefer (1986). For additional information on geology and exploration history see Mansure and others (2001), Waibel and others (2003), Johnson and others (2004), and Warpinski and others (2004). Areas of hydrothermal silica and drill-hole locations are shown on a map compiled by GeothermEx (2004, Fig. RYE00-1).
Rye Patch Map
Humboldt House Map
North of Humboldt House Map
Photos
Phillips Petroleum Co., Flow test Campbell E. No. 1. Rye Patch.
Phillips Petroleum Co., Humboldt House Campbell E No. 1, well head (Dick Benoit, Bill Desomer).
Well testing at Rye Patch.
Well pipes emitting steam.
Rye Patch geothermal plant cooling towers-construction complete.