Title: Molecular Simulation of Carbon Dioxide and Mineral Surface Interactions in Deep Saline Aquifers

Presenter: Craig Tenney

Affiliation: Sandia National Laboratories

Abstract: Accurate field-scale modeling of enhanced oil recovery and geological carbon sequestration requires accounting for CO2/brine/mineral interactions at the molecular and pore scales. We use state-of-the-art molecular dynamics simulations composed of ~500k atoms to investigate the interaction of supercritical CO2 and aqueous fluids with the basal surfaces of kaolinite and muscovite. In the presence of an aqueous phase, stable, non-wetting CO2 droplets form above the hydrophilic surfaces of kaolinite or muscovite. Simulations show the droplet is separated from the surface by layers of ordered water, preventing the CO2 droplet from interacting directly with the surface. This ordering of water on hydrophilic surfaces is enhanced by the presence of ions in brine solutions. On the hydrophobic surface of kaolinite, both CO2 and water interact directly with the surface, with CO2 being the preferred wetting phase. The ability to accurately model CO2 and brine interactions with mineral surfaces in a multiphase environment can aid the development of pore scale models and permit the evaluation of engineered solutions intended to alter large scale transport behavior by controlling local surface interactions.