A two-dimensional transient study on the impact of pore space connectivity on the immiscible two-phase flow in a water-wet, water-oil system

A multi-relaxation time lattice-Boltzmann model is employed to investigate the dynamic evolution of two immiscible phases through an artificial, randomly generated, porous structure. The flow is driven by a constant pressure gradient, in the absence of gravitational effects. Constraining attention to two dimensions, the impact of the morphological properties of the porous structure, generated using constant radius circular solid grains, on a water-wet, oil-water two-phase flow is studied. Variations in the pore space connectivity and topology are quantified by the Euler characteristic. It is found that the wetting phase saturation and the degree of pore network homogeneity have a significant impact on the dynamic evolution of the non-wetting phase topology, which is governed by a series of coalescence and snap-off events. It is also observed that the phenomenal macro-scale steady-state based on the velocity field does not also imply a temporal topological invariance of the displaced phases. The impact of the pore space morphology on the transient dynamics of the two-phase flow is monitored and quantified through a series of hydrodynamic and topological parameters that signify the underlying flow transport processes.