Development of the CSMA Mark II High Temperature Borehole Sparker Source

Abstract

A downhole sparker seismic source was developed at the CSM Geothermal Energy Project for imaging between boreholes at up to 3 km depth over a range of a few hundred metres. In September 1992 a major research and development programme was instigated to increase the penetration, operating temperature range, depth range and reliability of the tool. The programme consisted of laboratory studies of the spark discharge process and re-engineering of the tool. The upgraded tool can operate continuously at temperatures of up to 200?C for 10 hours and fire 700 times per deployment. The penetration, without stacking, has been increased from around 500 m to in excess of 850 m in granite. The performance of the tool has been established during surveys at the European HDR site at Soultz, France and from development trials at CSMA.