Time-lapse analysis of the surface seismic dataset at the Violet Grove CO 2 -EOR pilot project site shows no significant anomaly that can be attributed to the injected supercritical CO 2 between Phase I (March 2005) and Phase III (March 2007) of the project. However, the fixed-array vertical seismic profile (VSP) dataset exhibits small amplitude variations that may be associated with the CO 2 plume. The time-lapse analysis referred to here is based on the observation of amplitude and traveltime variations after the injection of approximately 40,000 t of CO 2 into the 1650 m deep, 20 m thick Cardium Formation over a period of two years. The ongoing analysis suggests that it would be hard to detect the CO 2 plume due to its being contained in very thin layers of relatively permeable sandstone members of the Cardium Formation. The seismic data, however, suggests that no leakage of CO 2 is taking place into shallower formations.
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