Effect of the number of water alternating CO2 injection cycles on CO2 trapping capacity
The APPEA Journal
School of Engineering
The CO2 storage capacity is greatly affected by CO2 injection scenario – i.e. water alternating CO2 (WACO2) injection, intermittent injection, and continuous CO2 injection – and WACO2 injection strongly improves the CO2 trapping capacity. However, the impact of the number of WACO2 injection cycles on CO2 trapping capacity is not clearly understood. Thus, we developed a 3D reservoir model to simulate WACO2 injection in deep reservoirs testing different numbers of WACO2 injection cycles (i.e. one, two, and three), and the associated CO2 trapping capacity and CO2 plume migration were predicted. For all different WACO2 injection cycle scenarios, 5000 kton of CO2 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 CO2 storage period was simulated. Our simulation results clearly showed, after 100 years of storage, that the number of WACO2 cycles affected the vertical CO2 leakage and the capacity of trapped CO2. The results showed that increasing the number of WACO2 cycles decreased the vertical CO2 leakage. Furthermore, a higher number of WACO2 cycles increased residual trapping, and reduced solubility trapping. Thus, the number of WACO2 cycles significantly affected CO2 storage efficiency, and higher numbers of WACO2 cycles improved CO2 storage capacity.