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This study analyzed trapping mechanisms for injection scenarios that can reliably store CO2 in aquifers for carbon capture and storage (CCS). The injection scenarios included continuous CO2 injection (CGI), cyclic CO2 injection, and water-alternating gas (WAG) injection, in which CO2 and water are injected alternately. The number of cycles varied from 2 to 20, with times of 1, 3, and 6 months for the shut-in period of cyclic injection and the water injection period of WAG. The residual, dissolved, and structure trapping were analyzed after CO2 injection and 180 years of monitoring. The simulation results showed that cyclic CO2 injection did not improve the residual and dissolved trapping compared to CGI and did not contribute to the stable storage of CO2. On the other hand, WAG significantly increased the residual and dissolved trapping of CO2 and decreased the structure trapping, contributing to CCS stability.
Lim et al. (Tue,) studied this question.