Characterization of HDR Reservoir by Seismic Signal While Drilling

Abstract

Seismic signals produced while drilling a Hot Dry Rock (HDR) geothermal well in Soultz-sous-Forets, France were detected by two downhole detectors in the granitic basement. Because there was a coherent component arriving at the two seismic stations, the cross-correlation of the signal between the stations was used to estimate the time delay of the direct and reflected phases as well as the autocorrelation of signals from each of the stations. The reflection image by the drill signal was correlated with reflection image by AE reflection method, distribution of microseismicity, and logging data, suggesting that the bottom of the artificial geothermal reservoir and permeable zone inside the reservoir have increased reflection coefficients.