Numerical study on flow behavior of CO₂ in an aquifer for risk assessment of carbon capture and storage

It is supposed that the leakage of injected CO₂ as the principal hazard due to the existence of fault occurs when CO₂ storage in an aquifer is targeted. Therefore it is very important to predict the migration of injected CO₂ dependent on time and space under the environment of underground. The quantitative estimation for the amount of storage and leakage of injected CO₂ is necessary for risk assessment of carbon capture and storage (CCS) through simulation study on the basis of the scenario of CO₂ leakage considering the specific geological condition such as permeability, porosity and the existence of fault. In this study, we constructed the reservoir model that aquifer and impermeable layers were alternately located in vertical direction of reservoir. Modeling of the fault was simplified by putting the thin zone that simulated the fault inside of analytical mesh zone. Using the constructed reservoir model, we carried out some simulation run. Changing geological structure containing fault, absolute permeability of fault and flow velocity of groundwater as a calculation parameter, we considered the effect of each parameter on flow behavior of CO₂ in an aquifer and quantified the amount of CO₂ leakage.