Contribution Of The Exploration Of Deep Crystalline Fractured Reservoir Of Soultz To The Knowledge Of Enhanced Geothermal Systems (Egs)

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Journal Article: Contribution Of The Exploration Of Deep Crystalline Fractured Reservoir Of Soultz To The Knowledge Of Enhanced Geothermal Systems (Egs)

Abstract
Over the past 20 years, the Soultz experimental geothermal site in Alsace, France, has been explored in detail by the drilling of five boreholes, three of which extend to 5 km depth. Data on geology, fluid geochemistry, temperature, microseismicity, hydraulics and geomechanics have been collected and interpreted by the various teams from the participating European countries and their international collaborators. Two reservoirs have been developed within granite at depths of 3.5 and 5 km. The reservoir at 3.5 km was formed from two wells, 450 m apart, both of which were subjected to hydraulic stimulation injections. The system was circulated continuously for 4 months at 25 kg/s in 1997 using a downhole pump, and yielded results that were extremely encouraging. The impedance reduced to 0.1 MPa/l/s, the first time this long-standing target had been attained. Construction of a deeper system began shortly afterwards with the drilling of 3 deviated wells to 5 km true vertical depth, where the temperature was 200°C. The wells were drilled in a line, 600 m apart at reservoir depth, and all were hydraulically stimulated and subjected to acidization injections. The 3-well system was circulated under buoyancy drive for 5 months in 2005 with injection in the central well, GPK-3, and production from the two outer wells, GPK-2 and GPK-4. This showed good linkage between one doublet pair, but not the other. Further acidization operations on the low-productivity well led to its productivity increasing to almost the same level as the other wells. Construction of a power plant at the site was completed in 2008 and a trial circulation with a production pump in one well and the other shut-in was conducted with power production. Downhole pumps are now installed in both production wells in preparation for long-term circulation of the system. In this article we present an overview of the principal accomplishments at Soultz over the past two decades, and highlight the main results, issues identified, and lessons learnt.

Authors 
Albert Genter, Keith Evans, Nicolas Cuenot, Daniel Fritsch and Bernard Sanjuan








Published Journal 
Comptes Rendus Geoscience, Date Not Provided





DOI 
10.1016/j.crte.2010.01.006


 

Citation

Albert Genter,Keith Evans,Nicolas Cuenot,Daniel Fritsch,Bernard Sanjuan. . Contribution Of The Exploration Of Deep Crystalline Fractured Reservoir Of Soultz To The Knowledge Of Enhanced Geothermal Systems (Egs). Comptes Rendus Geoscience. (!) .