Field Investigations and Temperature-Gradient Drilling at Marine Corps Air-Ground Combat Center (MCAGCC), Twenty-Nine Palms, CA

Abstract

The U.S. Navy’s Geothermal Program Office (GPO) has been conducting geothermal exploration activities in the Camp Wilson area of Marine Corps Air-Ground Combat Center (MCAGCC), Twenty-nine Palms, CA, for almost two years. Work has included self-potential (SP) surveys, fault structure analyses using LiDAR surveys, and drilling and assessment of five (5) temperature-gradient holes. For several decades the GPO has worked intermittently at MCAGCC at various sites. The objective of this project was to determine whether any utility-grade geothermal targets exist in this region. SP anomalies recently identified in Camp Wilson are of lower amplitude than similar anomalies recorded in previous SP studies conducted by the GPO. This additional SP work was designed to traverse mapped faults and lineaments identified in recently acquired LiDAR imagery. The objective of this work was to determine if SP anomalies coincide with faults and elevated temperatures from new or existing drilling. To date, three new anomalies have been identified in the Deadman Lake area of Camp Wilson. These are above local noise levels, are only partially defined, and do not coincide with existing temperature anomalies. The GPO has also collaborated with the Naval Construction Division (NCD) to utilize the Seabees to perform temperaturegradient drilling. The Seabees completed five temperature gradient test holes ranging from 600-1,000 feet. Each hole was completed with 3” steel tubing inserted to depth and filled with water to the surface. Baseline measurements show that at least two of the holes have elevated temperature gradients. Both the temperature-gradient drilling and the fault-structure analyses with the use of LiDAR mapping have proven to be extremely useful in assisting the GPO to define targets for intermediate to deep drilling in mid-to late 2010.