Time-lapse pressure-saturation discrimination for CO2 storage at the Snoehvit field

At the Snoehvit field, Barents Sea, the produced gas contains 5-8% CO2. This is separated from the sales gas at the Melkoeya LNG plant, piped back and re-injected into the saline aquifer Tubaen formation. The injected CO2 is monitored by time-lapse seismic data. Pressure and saturation changes are estimated by using near and far offset amplitude changes. The inverted pressure and saturation are used to predict expected time-shifts. The predicted time-shifts are then compared to conventional time-shifts estimated directly from the time-lapse seismic data. Empirical rock physics parameters linking pressure and saturation to the seismic parameters are estimated assuming linear relationships.