Chapter 5 - 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 CO2 storage, and the corrosive character of CO2 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 CO2–brine–rock interactions in GCS reservoirs, sealing formation integrity, and shallow groundwater impacts due to CO2leakage. Specifically, we describe CO2 behavior in the reservoir at core and field scales, caprock and well integrity near the injection well, as well as the impacts of CO2 on shallow groundwater combining experimental data, field observations, and reactive transport simulations. The migration of CO2 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 CO2 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 CO2 sequestration and the risks of CO2 leakage.