Relative permeabilities and coupling effects in steady-state gas-liquid flow in porous media: A lattice Boltzmann study

摘要

In this paper, the viscous coupling effects for immiscible two-phase (gas-liquid) flow in porous media were studied using the Shan—Chen-type single-component multiphase lattice Boltzmann model. Using the model, the two-phase flows in porous media with density ratio as high as 56 could be simulated and the contact angle of the gas-liquid interface at a solid wall is adjustable. To investigate viscous coupling effects, the co- and countercurrent steady-state two-phase flow patterns and relative permeabilities as a function of wetting saturation were obtained for different capillary numbers, wettabilities, and viscosity ratios. The cocurrent relative permeabilities seem usually larger than the countercurrent ones. The opposing drag-force effect and different pore-level saturation distributions in co- and countercurrent flows may contribute to this difference. It is found that for both co- and countercurrent flows, for strongly wet cases and viscosity ratio M> 1, k_nwincrease with the driving force and the viscosity ratio. However, for neutrally wet cases, the variations of k_nw and k_ware more complex. It is alsobserved that diferent initial pore-level saturation distributions may affect final steady-state distribution, and hence the relative permeabilities. Using the cocurrent and countercurrent steady flow experiments to determine the generalized relative permeabilities seems not correct.