(599f) A Study of Capillary Condensation Phenomena in Mesoporous Materials

The phase behavior of a fluid can be significantly affected by its confinement in nanopores. Within mesoporous materials, the strong fluid-solid interaction in the pores can induce a vapor to liquid phase change that occurs below the saturation pressure of the bulk fluid, a phenomenon which is known as capillary condensation. Identifying the conditions for which capillary condensation takes place in the subsurface under reservoir conditions plays an essential role in the design of unconventional oil and natural gas (UOG) resource systems. The focus of this study is the study of the phase behavior of low molecular weight (MW) alkanes confined in nanopores under reservoir relevant conditions and examining whether or not capillary condensation takes place.

For the study, we employ model mesoporous silicas, both amorphous and crystalline. We have selected for our study ethane as a model low MW hydrocarbon component of shale gas. We utilize a high-pressure thermogravimetric microbalance to study the adsorption and potential capillary condensation of ethane in the silica nanopores, as well as a volumetric system under cryogenic conditions. The experiments are complemented with models of the phase behavior, including the classical Kelvin Equation (KE), and a reformulated KE model based on the Peng-Robinson Equation of State (EOS). They are complemented by Grand Canonical Monte Carlo (GCMC) simulations to help reveal the possible mechanisms behind the fluid-solid interaction within the pores of these materials.