Impact of Injection Scenario on CO₂ Leakage and CO₂ Trapping Capacity in Homogeneous Reservoirs

The impact of different injection scenarios on the vertical CO₂ leakage and on the capacity of CO₂ storage in homogeneous reservoirs has been systematically investigated by comparing the total vertical CO₂ plume migration distance, the amount of free CO₂ and the capacities of capillary and solubility trapping obtained. A 3D homogeneous reservoir simulation model has been developed to simulate a CO₂ plume behavior for three different injection scenarios (water alternating CO₂ (WACO₂) injection, periodic injection and standard continuous CO₂ injection). The injection period was 20 years and the total amount of injected CO₂ was 20 Mton, for all injection scenarios. Then, after the end of the injection period, a storage period of 200 years was simulated. We then compared the CO₂ leakage and the amount of free, dissolved and trapped CO₂ between these three injection scenarios. The results show that, after 200 years CO₂ storage period, injection scenario significantly affects the vertical CO₂ leakage and the CO₂ trapping capacities in homogeneous reservoirs. Firstly, our results show that the standard continuous CO₂ injection and periodic injection scenarios lead to increase the CO₂ mobility and vertical CO₂ leakage. In addition, the simulation results show that the amount of CO₂ trapped (by both residual and solubility trapping) in the standard continuous CO₂ injection scenario is less than that trapped in the other injection scenarios. Thus, we conclude that injection scenario has an important effect on the CO₂ sequestration processes.