An Update on Geothermal Energy Resource Investigations, Chocolate Mountains Aerial Gunnery Range, Imperial Valley, California

Abstract

The US Navy’s Geothermal Program Office (GPO) conducted self-potential (SP) geophysical surveys in the Chocolate Mountains Aerial Gunnery Range (CMAGR) during November and December 2010 with assistance from Epsilon Systems Solutions, Inc. The focus of this work was the Camp Billy Machen training area extending northeast to a region east of the Hot Mineral Spa KGRA. The objective was to further define the controls on the 5.3 to 23.5 degrees F/100 feet temperature gradients identified through a temperature gradient hole drilling campaign in 2010. Over 1,200 stations at 200 foot spacing were occupied in a ~20 mi2 region in this western piedmont of the Chocolate Mountains. Two major anomalies were identified in the survey area. A negative 108-mV anomaly in the North (HMS-A) and a negative 96-mV anomaly in the South (HMS-B), both of which appear to be electro-kinetically produced anomalies. The anomalies are generally coincident with the higher shallow temperature gradients. The radial nature of the South anomaly suggests a flow of thermal fluids structurally controlled by faults analogous to regional patterns. Two target areas were identified and the drilling of two deeper test holes (programmed to 3,000 feet) is to be completed in mid-2011.