Magnetotelluric profile crossing the GRT1-2 geothermal doublet of the Rittershoffen EGS project, northern Alsace

Abstract

The Rittershoffen geothermal project includes a doublet of boreholes GRT1-2, which have been drilled till the Paleozoic basement at Rittershoffen, Northern Alsace (France). Well tests production achieved in 2013 and 2014 on both wells revealed, as expected, interesting hydraulic and thermic parameters, which held the project profitable economically. This successful geothermal project is achieved mainly to provide heat to an industrial bio-reffinery. In order to better understand and delineate at depth the geothermal reservoir, magnetotellurics measurements were done following an E-W profile crossing the GRT1-2 boreholes. The obtained resistivity values showed a very conductive anomaly located directly beneath GRT-1 borehole. It is located at ~2.2 km depth.