Monitoring of CO 2 injected at Sleipner using time-lapse seismic data

Abstract

Since October 1996, Statoil and its Sleipner partners have injected CO 2 into a saline aquifer, the Utsira Sand, at a depth of approximately 1000 m. The aquifer has a thickness of more than 200 m near the injection site and is sealed by thick shales. A multi-institutional research project SACS (Saline Aquifer CO 2 Storage) was formed to predict and monitor the migration of the injected CO 2. To this end two time-lapse seismic surveys over the injection area have been acquired, one in October 1999, after 2.35 million tonnes of CO 2 had been injected, and the second in October 2001, after approximately 4.26 million tonnes of CO 2 had been injected. Comparison with the baseline seismic survey of 1994 prior to injection provides insights into the migration of the CO 2. In this paper the results of the seismic interpretation will be shown, supported by synthetic seismic modelling and reservoir flow simulation of the migrating CO 2 at the two different time-steps.