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

摘要

The well, Coso Geothermal Exploratory Hole No. 1 (CGEH-1) was drilled at the China Lake Naval Weapons Center. Drilling was started on 2 September 1977, and the well completed on 1 December 1977 to 4845 ft. The well is an exploratory hole to determine geological and hydrothermal characteristics of the Coso Hot Springs KGRA (Known Geothermal Resource Area). During drilling, numerous geophysical and temperature surveys were performed to evaluate the geological characteristics of CGEH-1. LBL performed eight temperature surveys after completion of the well to estimate equilibrium reservoir temperatures. Downhole fluid samples were obtained by the U.S. Geological Survey (USGS) and Lawrence Berkeley Laboratory (LBL), and a static pressure profile was obtained. Two flow tests were attempted in 1978. The first test began September 5, 1978 using nitrogen stimulation to initiate flow; this procedure resulted in small flow and subsequent filling of the bottom hole with drill cuttings. The second test, on November 2, 1978, utilized a nitrogen-foam-water mixture to clean residual particles from bottom hole, following which nitrogen was again used to stimulate the well. The well remained dry after stimulation. Water influx was calculated at 4-5 gal/min as the well filled after unloading of the wellbore. (ERA citation 04:038526)