NUMERICAL STUDY ON APPARENT PERMEABILITY OF POROUS MEDIA IN SLIP GAS FLOWS BASED ON LATTICE BOLTZMANN METHOD

摘要

The unconventional gas reservoir has attracted more and more attention as the shale gas greatly expands worldwide energy supply, for which the gaseous fluid transport in complex porous domain is one important process as the shale gas is extracted. The apparent permeability of porous media is one important parameter in the related numerical model, however, its determination is still challenging. The apparent permeability varies with gas pressure, the porous media properties and gas-solid interactions based on the previous studies. For the slip gas flows, the velocity slip at the gas-solid interface in confined porous space is one significant difference compared with that on macro scale, which is caused by the gas rarefaction effect. In this work, a pore-scale LB model is established to simulate the gaseous fluid flow in the confined porous media. An effective curved boundary treatment is adopted for the porous surface and the validation test shows that the present model has superiority in capturing the slip phenomenon on the curved surfaces. Based on the numerical predictions, the different influential factors on the permeability of confined porous media are thoroughly studied, for which the gas rarefaction effect is considered.