Deep Structures of the Soultz-Sous-forets HDR Site (Alsace, France

Abstract

The site in Alsace (France) is located within the extensive thermal anomaly of the Rhine valley (fig. on the eastern margin of the Pechelbronn oil field. The site, which has been investigated since for its HDR potential, is currently being studied by scientists from France. Germany, and the United Kingdom, within the framework of a European programme supported by the CEC and coordinated by European Hot Dry Rock Association. I he Soultz site corresponds lo a local horst structure within the Upper Graben, bounded by North-trcnding faults dipping respectively West and East. íThe objective of the HDR project is the development of an experimental deep thermal exchanger in the granite basement, which is covered by 1400 m of sediments of Triassic to Tertiary age (Kappelmeyer et 1994). Two deep reconnaissance drill EPSl and GPKl, placed 500 m apart, have reached respective depths of 2200 and m in the granite basement. They are complemented by three refurbished oil wells used scismic monitoring (Elsass et al., 1994). Extensive single-well hydraulic injection and production experiments have been carried out between 1988 and 1994.