A Theoretical Study on the Permeability of Tight Media; Effects of Slippage and Condensation

ABSTRACT

Slippage and phase change are important factors which are affected on the permeability of gas in tight media. When dealing with micro/nano-scale media, conventional equations breaks down and can not be used to characterize gas transport in tight media. In this paper, we study gas transport in tight porous media to explore effects of the condensation and different types of gas molecule surface scattering on the permeability. Using the kinetic theory of gases and with an analogy between heat transfer and mass transfer, we derive first a formula for the effective mass diffusion coefficient in tight porous media. In particular, effects of the pore size, condensed phase saturation and grain surface roughness are determined. Then, the introduced model for the effective mass diffusion coefficient is implement to the dusty gas method to make it applicable for our investigation purposes. The well-known Kozeny–Carman equations and the fractal techniques are used to predict the absolute permeability of tight porous media. Our predictions for both self-diffusivity coefficient and the permeability are in good agreement with experimental data and numerical simulations.

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