Physics-Driven Investigation of Wettability Effects on Two-Phase Flow in Natural Porous Media: Recent Advances, New Insights, and Future Perspectives

Leveraging high-fidelity lattice Boltzmann simulations combined with analytical modeling, we establish a comprehensive micro-scale description of immiscible two-phase fluid displacement occurring during favorable and unfavorable displacement conditions in a heterogeneous porous medium under a wide range of wettability. The emergence of corner-flow events is found to promote a compact displacement pattern, leading to a maximum recovery efficiency of the defending fluid under the strong imbibition for both favorable and unfavorable displacement scenarios. Saturation of the invading fluid manifests the crossover in the displacement patterns from fingering to stable flow, as the wetting varies from drainage to strong imbibition. Quantifying the corner flow under both displacement conditions and strong imbibition reveals that corner-flow events are preferentially hosted by small-size pores and predominantly concentrated ahead of the primary fluid-fluid interface without perturbing the stability of the pore-body displacement. In addition to the numerical simulation, we developed an analytical model that can predict the saturation profile of invading fluid under given boundary conditions. Our study elucidates the fundamental control and interaction of wettability and heterogeneity on the dynamics of immiscible fluid displacement in porous media with implications in the description of subsurface flow and processes.

Automated summary

The study reveals that corner-flow events promote a compact displacement pattern, leading to maximum recovery efficiency under strong imbibition; the saturation of invading fluid results in the transition of displacement patterns from fingering to stable flow.