Tuning capillary flow in porous media with hierarchical structures

Immiscible fluid–fluid displacement in porous media is of great importance many engineering applications, such as enhanced oil recovery, agricultural irrigation, and geologic CO2 storage. Fingering phenomena, induced by the interface instability, are commonly encountered during processes somehow detrimental since hydrodynamic instabilities can significantly reduce efficiency. In this study, we report a possible adjustment pore geometry, which aims to suppress capillary fingering with hierarchical structures. Through pore-scale simulations theoretical analysis, demonstrate quantify combined effects wettability geometry on patterns, showing transition from compact mode. Our results suggest that higher porosity second-order structure, stay across wider range conditions. Combined our previous work viscous media, provide complete insight into fluid-fluid control wide flow conditions capillary- viscous-dominated modes. The conclusions benefit design microfluidic devices tailoring for better fluid efficiency at field scale.