Events :: Graduate Seminars :: Dissolution Trapping of CO₂ in Saline Aquifers by Marc Hesse, Stanford University

CO2-sequestration in deep geological formations has been suggested to reduce greenhouse gas emissions. At depth greater than 800 m, CO2 forms an immiscible CO2-rich vapor phase, and a small amount of CO2 dissolves in the brine. The density of the CO2-rich vapor phase is less than the density of the brine, but the density of the brine will increase with increasing CO2. In addition to a hydrodynamic seal that prevents upward migration, other trapping mechanisms should either immobilize the CO2 or eliminate its positive buoyancy, to ensure safe storage over long time scales. CO2 dissolved into the brine is considered trapped, because the dense CO2 saturated brine sinks to lower levels. Dissolution is also prerequisite for subsequent precipitation of CO2 as carbonate minerals. I will present recent results on the length and time scales and the rates of CO2 dissolution. I also discuss the implication on site selection and the challenges this process poses for field scale simulation of CO2 storage.