Effects of impurities on CO2 transport, injection and storage

Abstract Effects of impurities in CO 2 streams on geological storage of CO 2 have been investigated. A number of key issues have been addressed, and several significant findings have been made. Highlighted among the findings are: (1) non-condensable impurites such as N 2 , O 2 and Ar greatly reduce CO 2 storage capacity of geological formations, and there is a maximum reduction of the storage capacity at a certain pressure under a given temperature. By contrast, impurities which are more condensable than CO 2 , such as SO 2 , can increase the storage capacity, and there is a maximum increase at a certain pressure under a given temperature; (2) change of density caused by non-condensable gas impurities results in lower injectivity of impure CO 2 into geological formations. However, above a threshold pressure range the injectivity could reach the level of pure CO 2 due to lowered viscosity; (3) non-condensable impurities increase the buoyancy of the CO 2 plume. This would negatively affect the efficiency of solubility trapping and residual trapping of CO 2 . (4) the effect of SO 2 on reduction of rock porosity and hence CO 2 injectivity would be much smaller than previously thought. A simple formula has been developed to enable quick determination of the effect.