Potential CO2 leakage from geological storage sites: advances and challenges

This paper provides an overview of recent advances and remaining challenges in predicting, quantifying, detecting and mitigating carbon dioxide (CO2) leakage from geological storage sites to overlying aquifers and the atmosphere. Sequestering carbon dioxide in deep geological formations offers a promising solution for reducing anthropogenic carbon dioxide emissions. However, there remain critical questions regarding the storage integrity and leakage potential, which warrant further consideration. Leaking carbon dioxide out of the reservoir may affect the shallower subsurface - for example, the quality of drinking groundwater, which causes great health risk and public concern. In addition, high concentrations of carbon dioxide in soil would be fatal for vegetation near the surface. Trapping mechanisms and potential leakage pathways are discussed. A detailed review of monitoring methods including atmospheric monitoring, near-surface and subsurface monitoring methods are presented and discussed. In addition, recent numerical and analytical models for predicting the behaviour of carbon dioxide plume and leakage potential are discussed. Despite various research efforts and significant advances made on different aspects of this issue, further investigation is required to ensure safe and effective implementation of large-scale carbon dioxide sequestration projects.