SIMULATION OF TIME LAPSE MINERAL CARBONATION AND ISOTOPE FRACTIONATION OF INJECTED CO2 IN AQUIFER: IMPLICATIONS FOR MONITORING CO2 SEQUESTRATION

A theoretical aquifer model during CO2 sequestration predicts time‑lapse mineral carbonation and isotope fractionation of injected CO2 in sediment. The kinetics of CO2 hydration and the dissociation of carbonic acid are used to simulate the model. The conversion rate of CO2 into hydrogen and carbonate ions in an aqueous solution is controlled by diffusion and reaction kinetics. Geologic sequestration of CO2 has become one of the promising ways to reduce atmospheric emission of CO2 from human activity. However, the current and future effects of geologic storage formation after injecting CO2 are not known well. Therefore, monitoring and verification of CO2 sequestration is very important in carbon capture and sequestration projects. In this study, we injected CO2 for a certain amount of time period and shut in the injection well and generated CO2 flume and properties distribution in the reservoir. Using data generated from the simulator, we developed a mathematical model based on a transport‑reaction equation and calculated the abundance of carbon and oxygen stable isotope in the reservoir with respect to time which allows us to predict CO2 saturation in sediment or CO2 flume distribution by sampling reservoir water. In addition, injected CO2 can be migrated into a ground water aquifer. The migrated CO2 can be detected by comparing the stable isotopes in sampled groundwater and predicted stable isotopes. These results indicate significant potential of the theoretical aquifer model for monitoring and verification of CO2 sequestration into the sediment.