A Review Of Studies Examining The Potential For Groundwater Contamination From Co2 Sequestration

Geologic carbon sequestration (GCS) is the process of injecting CO2 into deep subsurface rock formations such as into depleted oil and gas reservoirs or deep saline aquifers for long-term storage. Over the last decade, a number of field, laboratory, and modeling studies have been undertaken to assess the feasibility and safety of CO2 geologic storage, including their potential impact on shallow groundwater aquifers overlying target CO2 storage reservoirs. This chapter provides a review of the literature on the primary concerns to groundwater quality from GCS and practices to mitigate or avoid impacts to water. The review covers possible pathways by which CO2 can leak from GCS reservoirs, the potential hazards associated with leakage of dissolved CO2 into shallow groundwater, state-of-the-art monitoring strategies for CO2 leakage, and an overview of guidelines and regulations in the United States that seek to minimize potential impact. Several knowledge gaps and science needs still remain for understanding the impacts of large-scale deployment of GCS to groundwater including likely leakage scenarios, pathways and associated fluxes, key characteristics of aquifers that could make them vulnerable to degradation upon CO2 intrusion, and the development of reduced-order models and effective monitoring strategies for understanding and designing appropriate responses to CO2 leakage.