Abstract:

Because of the unknown faults, fractures in the cap rock, the deep stored CO₂ may move upward, the intrusion will impact shallow groundwater quality. After the leakage stopped, the affected aquifer may show self-repair capacity under the natural flow field. In this study, an injection test field was selected as example, and the reactive transport modeling software TOUGHREACT was used to simulate the self-repair capacity. The simulation results showed that, the intrusion of leaked CO₂ would decrease the pH of target aquifer, and trigger the dissolution of carbonate minerals. After the leakage stopped, the pH would be increased under natural conditions, but the concentration of Ca would increased because of the dissolution of calcite along the flow path, which means the self-repair capacity of target aquifer is not good enough to scavenge the impacts of CO₂ leakage.

Key words: carbon dioxide leakage, confined aquifer, self-repair, calcite