(37i) Calculating the Interfacial Properties of CO2/Water/Silica Systems Using Monte Carlo Molecular Simulations

Rall, A. R., University at Buffalo, The State University of New York
Errington, J. R., University at Buffalo
Geological sequestration has the potential to occupy a strategic role in the reduction of carbon dioxide emissions. Before injecting CO2 into a potential storage site, one must first assess the capability of the site to retain the injected CO2. Understanding the interactions between the fluid CO2-rich and water-rich phases and the caprock mineral of a site is particularly important. These interactionsâ??in the form of the CO2/water/caprock contact angle and CO2/water interfacial tensionâ??dictate the breakthrough pressure, that is, the pressure at which the CO2-rich phase may leak due to capillary failure. We present here the use of Monte Carlo methods to measure the interfacial tension and contact angles of CO2/water mixtures near a silica surface. We apply a combination of interface potential free energy techniques and expanded ensemble simulations to measure differences in these interfacial properties over a range of temperature and pressure conditions for several combinations of available water and CO2 molecular models.