145 QUAL I TÉ GÉOPHYSIQUEAPPLIQUÉE 4 Towards a revisited geothermal conceptual model in the Upper Rhine Graben A. Genter, C. Baujard, C. Glaas and V. Maurer New concepts of deep geothermal energy in Western Europe were mainly initiated by a French-German consortium in the Upper Rhine Graben, at Soultz-sous-Forêts, France. A series of deep boreholes were drilled till 5 km deep within a crystalline basement, reputed tight and lying below the former Pechelbronn oil field where the first electric log was achieved for detecting petroleum in sedimentary reservoirs in the 1920s. The main geothermal concept developed at Soultz-sous-Forêts, was to create from scratch, a down-hole heat exchanger by injecting water via a vertical borehole in a very low matrix porosity crystalline rock and by pumping it out hotter via deviated boreholes. It was derived from geothermal projects developed worldwide (US, Japan, Germany, UK), called Hot Dry Rock (HDR). However, after the achievement of several deep drilling at Soultz, the HDR concept slightly evolved to become Enhanced or Engineered Geothermal Systems (EGS), consisting of pumping hot © EDP Sciences, 2025 DOI: https://doi.org/10.1051/978-2-7598-3752-6.c004
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