Monitoring of Reservoir Behavior at Soultz HDR Field by Super-Resolution Microseismic Mapping

Abstract

The second hydraulic stimulation at a depth around 4500m to 5000m was carried out at Soultz HDR site, Alsace, France in 2003 to create a deep reservoir for a pilot plant. Around 38,000 m3 of heavy brine and water was injected in the 5005m borehole GPK-3 (which was drilled in 2002), and the other deep well GPK-2. The induced microseismic events were detected by a seismic network consisting of three downhole 4 component accelerometers and two 3-component geophones. The authors picked onsets of events using automatic picking software and located the events on-site. The number of triggered events during the stimulation was approximately 87,000, and we picked approximately 8,100 high quality events. The authors manually re-picked the events, which are automatically picked on-site, and located them by JHD (joint hypocenter determination) and the coherence-collapsing methods. The relocated seismic cloud extends mainly NS direction around GPK-3 and N 45?W around GPK-2.