Phase behavior and flow in shale nanopores from molecular simulations

Abstract

Phase behavior and flow in shale nanopores, due to fluid heterogeneity, cannot be described by bulk and continuum-based formulations. The interactions between fluid and rock molecules are important in both phase behavior and flow. As a result, frameworks from bulk equations of state in phase behavior, and continuum mechanisms and Klinkenberg slippage in flow may become inapplicable. Recently, we have studied both phase behavior and flow in nanopores using density functional theory and various molecular simulations. This work addresses a number of issues related to the adsorption of mixtures of hydrocarbons, carbon dioxide and water as well as methane flow at different pressure conditions in nanopores. For flow, we use the dual control volume-grand canonical molecular dynamics (DCV-GCMD) simulation as in our previous work. We use a smaller pressure difference between high and low pressure reservoirs connected to the nanopores. We find that similar to our past work, the flux of methane in the slit pores can be two orders of magnitude higher than the results from the Hagen-Poiseuille equation.