Time dependent self-diffusion coefficient of methane molecules confined into micropores structure of a sandstone

Abstract

In this work, the effect of pore structure of a sandstone on the molecular displacement of confined methane gas is analyzed. It was found that the self-diffusion coefficient of a methane molecule depends on the pore size distribution an their connectivity. In particular, the time dependent self-diffusion coefficient exhibits a maximum which is correlated with the effect of the molecular confinement. It was found that a sandstone with small pores and/or pores bad connected traps the gas more efficiently than other pores structures. This fact enable to understand the scattered values which the residual trapped gas saturation measures exhibit with different sandstones.