Relative permeability of three immiscible fluids in random porous media determined by the lattice Boltzmann method

•Multicomponent model based on lattice Boltzmann method was constructed.•Three immiscible fluids flow in porous was simulated by the MRT lattice Boltzmann model.•The effects of capillary number, wettability and viscosity ratio on the relative permeability of three phase were analysed. In this article, three immiscible fluids flowing in 3D porous media were simulated by the pseudopotential-based multiple relaxation time lattice Boltzmann model for multicomponent/multiphase flow, and the effects of capillary number (Ca), wettability and viscosity ratio (M) on the relative permeability were analysed. The simulation results show that the relative permeability of the three fluids increases with increasing Ca, whereas wettability influences the effect of Ca on the wetting phase (WP) relative permeability. The enhancement of porous wettability in the three-phase system leads to a decrease in the WP relative permeability and an increase in the relative permeability of the other two fluids. When M > 1, the nonwetting phase (NWP) has a lubricating effect and its relative permeability increases with increasing M in wet porous media, whereas the other two fluids are insensitive to M variations compared with the NWP.