Effect of pore structure on liquid-gas flow in porous media

Pore structure significantly governs the seepage characteristics of porous media. This study investigates this influence by comparing the infiltration behavior of homogeneous and heterogeneous porous structures through microfluidic experiments and numerical simulations. It constructed one heterogeneous structure derived from real rock cores and four homogeneous structures with regular particle arrangements, all with identical porosity. Heterogeneous structure and homogeneous structure exhibit similar finger-like flow patterns and minimal differences in water saturation. Air displacement in dead-end pores is driven by internal-external pressure differences, with water replacing air only when internal pressure surpasses external pressure. In homogeneous models, water pressure shows pulse-like fluctuations; pressure peaks due to interfacial resistance decrease from approximately 88 Pa to approximately 38 Pa as pore size increases. Meniscus evolution, linked to pore width variations, presents three states: Stretching, equilibrium, and expansion. This study clarifies the dominant role of pore morphology in fluid transport, providing a theoretical basis for optimizing structural design and efficiently regulating seepage processes in engineering applications such as resource extraction and CO₂ sequestration.