Reservoir Engineering To Accelerate the Dissolution of CO₂ Stored in Aquifers

It is possible to accelerate the dissolution of CO₂ injected into deep aquifers by pumping brine from regions where it is undersaturated into regions occupied by CO₂. For a horizontally confined reservoir geometry, we find that it is possible to dissolve most of the injected CO₂ within a few hundred years at an energy cost that is less than 20% of the cost of compressing the CO₂ to reservoir conditions. We anticipate that use of reservoir engineering to accelerate dissolution can reduce the risks of CO₂ storage by reducing the duration over which buoyant free-phase CO₂ is present underground. Such techniques could simplify risk assessment by reducing uncertainty about the long-term fate of injected CO₂, and could expand the range of reservoirs which are acceptable for storage.