Efficiency of CO2 Storage in a Domed Structure

When storing CO2 in a saline aquifer, it is desirable to have a structural trap, such as a domed closure, to limit the lateral migration of CO2. Domed structures may be formed in sandstone formations by migration of underlying salt bodies (halokinesis). In this study, we have created such a model of a hypothetical storage site in a domed structure, based on a real formation, using existing geological and petrophysical data. CO2 storage was simulated using the Eclipse 300 simulator with the CO2STORE module. Injection was initially controlled by rate, but was constrained by pressure build-up in the injection wells and at the crest of the dome. In additional, we monitored migration of CO2 past the dome spill point. A base case model was simulated and the a range of sensitivity cases investigated including the effect of aquifer size and heterogeneity. The results are very sensitive to boundary conditions. Notably, if the reservoir is open, the capacity may be limited due to migration across the spill point. The storage capacity also depends on reservoir heterogeneity, particularly if there are extensive layers of low permeability.