| Abstract |
In-situ stresses are key parameters in the design of a bot-dry-rock operation for the extraction and economic use of geothermal energy. In-situ stresses control the pressure to initiate and activate fractures and joint systems, determine the underground fluid flow path, or influence the stability of un-cased borehole sections. Therefore, since the early days of the European HDR - project at Soultz-sous-Forets, the tectonic situation in the Upper Rhine-valley has been extensively investigated by hydraulic-fracturing stress measurements, so far at depth down to approximately 3.5 km. The results of the measurements yield - the orientation of the acting maximum horizontal compression of N - S to NNW - SSE in accordance with both the spatial distribution of the seismic events induced during the stimulation experiments and the existing stress data for Central Europe, tectonics in the Upper Rhine-valley. - the stress-regime with notably low horizontal stresses, typical for the normal faulting T he comparison with existing stress data of the surrounding tectonic units and the extrapolation of the stresses to the proposed reservoir depth at 5 h yield important data for both the technical planning of the drilling and casing cementation operation and the design of future circulation tests at the Soultz test-site. |