Reactive Transport Modeling of Geological Carbon Storage Associated With CO2 and Brine Leakage

Abstract Geochemistry and reactive transport play a critical role in geologic carbon sequestration (GCS), because dissolution and mineral trapping provides long-term stable CO 2 storage, and the corrosive character of CO 2 might also affect the function of sealing formations and increase the risks to overlying groundwater quality. An overview of geochemical modeling studies related to GCS is presented in this chapter, including CO 2 –brine–rock interactions in GCS reservoirs, sealing formation integrity, and shallow groundwater impacts due to CO 2 leakage. Specifically, we describe CO 2 behavior in the reservoir at core and field scales, caprock and well integrity near the injection well, as well as the impacts of CO 2 on shallow groundwater combining experimental data, field observations, and reactive transport simulations. The migration of CO 2 from sequestration reservoirs into shallow drinking water aquifers through leakage pathways is of special interest because it could result in a system failure with released toxic trace metals that exceed EPA National Primary Drinking Water Standards. Since most of the reactive transport parameters and the reaction patterns with CO 2 are site-specific, uncertainty factors such as reaction kinetics and formation heterogeneity need to be carefully considered to make a proper uncertainty assessment to quantify CO 2 sequestration and the risks of CO 2 leakage.