Exploratory Well At Long Valley Caldera Geothermal Area (Sorey, 1985)

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Exploration Activity: Exploratory Well At Long Valley Caldera Geothermal Area (Sorey, 1985)

Exploration Activity Details
Location Long Valley Caldera Geothermal Area
Exploration Technique Exploratory Well
Activity Date 1976 - 1985

Usefulness useful
DOE-funding Unknown

 
Exploration Basis
Additional drilling activities continued between 1976 and 1985. Several of these holes were full-size wells, including:

  • The (Unocal) Mammoth-1 well, drilled by Union Oil Company in 1979 at Casa Diablo to 1605 m depth, with maximum encountered temperature of 152.7°C at 121m but a temperature of 102.2°C at TD
  • The Clay Pit 1 (CP-1) well also drilled by Union Oil Company in 1979 into the Resurgent Dome to 1799 m depth, with maximum encountered temperatures of 147.8°C[1]
  • Wells 68-28 and 13-26, drilled by Santa Fe Geothermal Inc. on the Resurgent Dome after 1980 (temperature, lithology, structural data, and specific completion dates for these wells were unavailable for the purposes of this review).[2]

 
Notes
The (Unocal) Mammoth-1 well was the first well drilled at Casa Diablo to test the deep production potential from the intracaldera Bishop Tuff and caldera basement. It was also the first well to intersect the metasedimentary landslide block at 466 m depth beneath the caldera's southern moat, a tumultuous mix of metapelite and granite that separates the Early Rhyolite reservoir from the underlying Bishop Tuff.


Additional References
  1. Michael L. Sorey. 1985. Present State of the Hydrothermal System in Long Valley Caldera, California. In: Transactions. GRC Annual Meeting; 08/26/1985; Kailua-Kona, Hawaii. Kailua-Kona, Hawaii: Geothermal Resources Council; p. 485-490
  2. Michael L. Sorey,Gene A. Suemnicht,Neil C. Sturchio,Gregg A. Nordquist. 12/1991. New Evidence On The Hydrothermal System In Long Valley Caldera, California, From Wells, Fluid Sampling, Electrical Geophysics, And Age Determinations Of Hot-Spring Deposits. Journal of Volcanology and Geothermal Research. 48(3-4):229-263.