Effects of impurities on CO2 transport, injection and storage

AbstractEffects of impurities in CO2 streams on geological storage of CO2 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 N2, O2 and Ar greatly reduce CO2 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 CO2, such as SO2, 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 CO2 into geological formations. However, above a threshold pressure range the injectivity could reach the level of pure CO2 due to lowered viscosity; (3) non-condensable impurities increase the buoyancy of the CO2 plume. This would negatively affect the efficiency of solubility trapping and residual trapping of CO2. (4) the effect of SO2 on reduction of rock porosity and hence CO2 injectivity would be much smaller than previously thought. A simple formula has been developed to enable quick determination of the effect