Investigation of shale gas flows under confinement using a self-consistent multiscale approach

Abstract

This report summarises our recent findings on non-ideal gas flow characteristics in shale nanopores facilitated by our strongly-inhomogeneous kinetic model. As there are a significant portion of nano-scale pores in shale, gas molecule size is comparable to both the gas mean free path and the characteristic length of the flow domain, and various factors including fluid-solid and fluid-fluid interactions, pore confinement, surface roughness, and non-equilibrium effect need to be considered in a self-consistent manner. These factors are either considered in the governing equation according to the dense gas and mean-field theories, or through the boundary condition based on molecular dynamics simulations. Our kinetic model results are consistent with the molecular dynamics data at the molecular scale and converge to the continuum predictions when pores become large. This model serves as an accurate tool to investigate multiscale transport of shale gas and is helpful for upscaling from the microscopic to continuum levels with a firm theoretical basis.

Cited as: Shan, B., Ju, L., Guo, Z., Zhang, Y. Investigation of shale gas flows under confinement using a self-consistent multiscale approach. Advances in Geo-Energy Research, 2022, 6(6): 537-538. https://doi.org/10.46690/ager.2022.06.11

References

Guo, Z., Zhao, T., Shi, Y. Simple kinetic model for fluid flows in the nanometer scale. Physical Review E, 2005, 71(3): 035301.

He, X., Doolen, G. D. Thermodynamic foundations of kinetic theory and lattice Boltzmann models for multiphase flows. Journal of Statistical Physics, 2002, 107(1): 309-328.

Luo, L. Unified theory of lattice Boltzmann models for nonideal gases. Physical Review Letters, 1998, 81(8): 1618.

Shan, B., Wang, R., Guo, Z., et al. Contribution quantification of nanoscale gas transport in shale based on strongly inhomogeneous kinetic model. Energy, 2021, 228: 120545.

Shan, B., Wang, P., Wang, R., et al. Molecular kinetic modelling of nanoscale slip flow using a continuum approach. Journal of Fluid Mechanics, 2022, 939.

Shan, B., Wang, P., Zhang, Y., et al. Discrete unified gas kinetic scheme for all Knudsen number flows. IV. Strongly inhomogeneous fluids. Physical Review E, 2020, 101(4): 043303.

Wu, L., Liu, H., Reese, J. M., et al. Non-equilibrium dynamics of dense gas under tight confinement. Journal of Fluid Mechanics, 2016, 794: 252-266.