The Impact of Aquifer/Caprock Morphology on CO2 Storage in Saline Aquifers

The CO2 storage project at Sleipner has shown that the topography of the aquifer/caprock interface can have a significant effect on the migration paths of CO2 in an aquifer (Singh et al 2010). Therefore when appraising any reservoir or aquifer for CO2 storage, it is important to characterise the interface and to ensure that it is modelled adequately. Often simulations assume a sharp boundary smooth between the aquifer and the caprock. However studies of outcrops show that a variety of types of interface may arise in nature, depending on the depositional setting. For example, Shariatipour et al (2012) have shown that there may be a gradual transition from sand-rich facies in the aquifer to mud-rich facies in the caprock. Syversveen et al, have investigated the impact of top-seal morphology on CO2 storage capacity and migration patterns, and concluded that it is important to model geological details in order to predict CO2 migration. We intend to investigate different types of caprock/aquifer interface to determine how these affect the pressure build-up under the caprock and the amount of CO2 which dissolves in brine. This will enable us to identify which type of aquifer/caprock has the greatest potential for storing CO2 securely.