Numerical and experimental study on gas flow in nanoporous media

• A complete modelling is introduced to reflect transport characteristics.
• The general transport equation is most appropriate for gas flow in nanoporous media.
• The values of diffusion coefficient and intrinsic permeability can be obtained simultaneously.

With the increasing attention being paid to the development of unconventional reservoirs, such as shale gas or tight gas reservoirs with nanoscale pores, over the last few years, there is a great demand to develop a coherent theoretical framework that explains the transport mechanisms that take place in a nanoporous medium. In this paper, a complete modelling workflow that spans the mesoscale to the macroscale, including the lattice Boltzmann model (LBM) and Navier–Stokes equations, is introduced to reflect these transport characteristics. Gas flow for different pore diameters and Knudsen numbers is simulated by LBM. Comparison between physical experimental measurements and the LBM simulation results shows that the general transport equation is most appropriate for describing gas flow in nanoporous media and that the values of the diffusion coefficient and intrinsic permeability can be obtained simultaneously using this equation. Intrinsic permeability decreases faster than the diffusion coefficient with the decreasing average pore diameters in nanoporous media. The general transport equation has been verified to reflect the mechanisms of flow and diffusion in nanoporous media, and it also provides a theoretical basis to assess the results attained from numerical simulations.