Study of Recorded Seismicity at the In Salah (Algeria) Carbon Capture and Storage Project

The In Salah Joint Venture carbon capture and storage project at Krechba, Algeria began injecting CO2 in 2004. This study makes use of microseismic event data recorded by a single geophone. Information from shear waves enables fracture directions and densities to be inferred and we find fractures striking N145°E, in agreement with the regional direction of maximum horizontal stress. There is no evidence for any temporal change in shear-wave splitting parameters in the time frame studied. This implies that CO2 injection is reactivating pre-existing fractures. We are able to obtain only very approximate event locations which suggest that events occur at or below the reservoir level, with no change over time.