Experimental Study of the Impact of Salinity and Temperature on Convection Mechanism During CO2 Storage in Saline Aquifers

One of the most effective and safe mechanisms for CO2 storage in saline aquifers is dissolution mechanism by which CO2 will be dissolved in brine and forms CO2-saturated brine. The more CO2 will be trapped by this mechanism, the more successful the storage project would be since risk of leakage will be reduced. However, the rate of dissolution of CO2 in brine is a function of active mass transfer mechanisms in storage conditions. If convection mechanism is not the active mechanism and CO2 mass transfer into the brine is only happening due to diffusion mechanism, the CO2 transfer will be very slow and the amount of dissolved CO2 will be small compare to the system when convection mechanism is active.

In this paper our main objective is to experimentally study the effect of parameters such as; salinity, and reservoir temperature on convection mechanism and therefore on CO2 storage in saline aquifers. For this aim a series of high-pressure high-temperature experiments were performed in a special designed PVT bead pack cell. Next, based on the pressure data, effect of above parameters on CO2 dissolution, Rayleigh number and the onset time of convection was studied. Furthermore, to investigate effects of these parameters on convection mechanism and also to study impact of convection mechanism on CO2 dissolution, Sherwood number and the time, when it reaches to its maximum value, were calculated in each experiment.