Characterization of fluid transport properties of the Hot Dry Rock reservoir Soultz-2000 using induced microseismicity

Abstract

Hydraulic stimulation is a procedure for increasing the permeability of a reservoir. At the geothermal site of Soultz, France, such experiments have been carried out since 1993 at different depths. During the Soultz-2000 hydraulic stimulation, about 7200 seismic events were located using a borehole and free surface seismic network. We analyse the spatio-temporal distribution and density of the events to estimate the large-scale permeability of the medium. We assume that the main triggering mechanism is a pore-pressure diffusion process. Based on this idea, we apply different, already developed, methods for the Soultz-2000 hydraulic stimulation. We obtain two independent scalar permeability estimations, a permeability tensor and a heterogeneous reconstruction of the hydraulic diffusivity. The results agree very well with independent in situ tests.