Lattice Boltzmann simulation of immiscible two-phase displacement in two-dimensional Berea sandstone

Understanding dynamic displacement of immiscible fluids in porous media is important for carbon dioxide injection and storage, enhanced oil recovery and non-aqueous phase liquid contamination of groundwater. However, it has not been well understood at the pore scale. This work therefore focuses on the effects of interfacial tension, wettability and viscosity ratio on displacement of one fluid by another immiscible fluid in a two-dimensional (2D) Berea sandstone using colour gradient lattice Boltzmann model with a modified implementation of wetting boundary condition. Through invasion of the wetting phase into the porous matrix, it is observed that the viscosity ratio plays an important role in the non-wetting phase recovery. At the viscosity ratio (λ) of unity, the satu-
ration of the wetting fluid is highest, and it linearly increases with the time. The displacing fluid saturation reduces drastically when λ increases to 20, however, when λ is beyond 20, the reduction becomes less significant for both imbibition and drainage. The front of the bottom fingers is finally halted at a position near the inlet as the viscosity ratio increases to 10. Increasing the interfacial tension generally results in a higher saturation of the wetting fluid. Finally, the contact angle is found to have limited effect on the efficiency of displacement in the 2D Berea sandstone.