Evaluation of Coso Geothermal Exploratory Hole No. 1 (CGEH-1), Coso Hot Springs KGRA, China Lake, California


C. Goranson, R. Schroeder, and J. Haney

Geo Location:

Coso, California


Stanford Geothermal Workshop




Well Testing and Formation Evaluation



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The well CGEH-1 (Coso Geothermal Exploratory Hole No. 1) was drilled at the China Lake Naval Weapon Center under the supervision of DOE/NVO and CER Corporation by Big 0 Drilling Company. They started drilling on 2 September 1977 and completed the well on 1 December 1977 to 4845 feet. The well is an exploratory hole to determine geological and hydrotheinal characteristics of the Coso Hot Springs KGRA. During drilling, numerous geophysical and temperature surveys were performed to evaluate the geological characteristic s of CGEH-1. LBL performed eight temperature surveys after completion of the well to estimate equilibrium reservoir temperatures. Downhole fluid samples were obtained by USGS and LBL, and a static pressure profile was obtained.

Two flow tests were attempted in 1978. The first test began September 5, 1978 used nitrogen stimulation to initiate flow, but resulted in small flow and subsequent filling of the bottom hole with drill cuttings. The second test, on November 2, 1978, utilized a nitrogenfoam- water mixture to clean residual particles from bottom hole and nitrogen was then used to stimulate the well. The well again was dry after stimulation. Water influx was calculated at 4-5 gal/min as the well filled after unloading of the wellbore.

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