ANALYSIS OF INDUCED SEISMICITY FOR FAULT ZONE IDENTIFICATION

The location of micro-seismic events induced by various fluid injectio ns in two wells drilled in granite has helped identify two plannar str uctures at distances up to 100 m from the injection wells. While sonic and petrofabric logs confirm the results of the microseismicity analy sis, electrical imaging logs have been found to be inapropriate for de termining the dip and azimuth of such large structures. Further, in a hydraulically opened fracture system, the microseismicity is found to outline only zones with high interstitial pressure; it does not help i dentify the main flow zones away from the injection wells.