Effect of Variable Brine Salinities on CO2 Trapping: Implications for CO2 Storage in Saline Acquires
Haiyang Zhang, Mohammed Al Kobaisi, Yihuai Zhang, Muhammad Arif
Abstract
Abstract Injecting CO2 into the saline aquifer is considered to be an effective strategy to mitigate CO2 emissions. Saline aquifers are known to have a wide range of salinities and several evidences showed that different brine salinities give rise to different CO2-brine-rock wetting behaviors as well as different CO2 solubility potential. This will ultimately influence the CO2 plume migration behavior and the overall performance of a CO2 sequestration project. However, associated field-scale CO2 capacity predictions in different saline aquifers received little attention. This study conducts field-scale numerical simulations to analyze the effect of aquifer salinity on the CO2 storage potential. Different CO2-brine flow behaviors undervariablebrine salinities were considered. The results showed that an increase in the plume migration distance was observed in a higher salinity aquifer.While an increase in the brine salinity would result in an increase in residual trapping but a decreased solubility trapping capacities.Also, higher salinity formation observed more mobile CO2 and thus exhibit a worse sealing efficiency. We point out that residual trapping capacity evaluation should consider both residual CO2 saturation and the CO2 occupied volume, which both are strong functions of brine salinity.