Effect of the number of water alternating CO2 injection cycles on CO2 trapping capacity

Abstract

The CO storage capacity is greatly aected by CO injection scenario – i.e. water alternating CO (WACO ) injection, intermittent injection, and continuous CO injection – and WACO injection strongly improves the CO trapping capacity. However, the impact of the number of WACO injection cycles on CO trapping capacity is not clearly understood. Thus, we developed a 3D reservoir model to simulate WACO injection in deep reservoirs testing dierent numbers of WACO injection cycles (i.e. one, two, and three), and the associated CO trapping capacity and CO plume migration were predicted. For all dierent WACO injection cycle scenarios, 5000 kton of CO and 5000 kton of water were injected at a depth of 2275 m and 2125 m respectively, during a 10-year injection period. Then, a 100-year CO storage period was simulated. Our simulation results clearly showed, after 100 years of storage, that the number of WACO cycles aected the vertical CO leakage and the capacity of trapped CO . The results showed that increasing the number of WACO cycles decreased the vertical CO leakage. Furthermore, a higher number of WACO cycles increased residual trapping, and reduced solubility trapping. Thus, the number of WACO cycles signicantly aected CO storage eciency, and higher numbers of WACO cycles improved CO storage capacity.