Pore-scale study on interfacial force-induced residue mobilization under immiscible ternary fluids flow

Abstract

Immiscible three-phase flow and the trapping/mobilizing mechanism are significant to many water and energy applications such as water infiltration, oily wastewater treatment, CO2 sequestration, and water-alternating-gas (WAG) for oil recovery enhancement. This work targets the ternary fluid system, namely water, gas, and oil, to uncover the significant role of interfacial forces in the transient flow behavior and trapped-phase mobilization. From both the lattice Boltzmann method (LBM) modeling and experimental observations, we firstly showed the deformation and mobilization process of the oil droplet when interacting with water droplet in air. The re-distribution of oil phase reveals the strong interfacial interactions at the water-gas-oil three-phase contact point (fluid-TPCP). For the more complicated three-phase flow in porous media, our visualization results also showed that the trapped oil phase, which initially adhered to rough surfaces or inside dead-end pores, was extracted by the pulling effect at fluid-TPCP during WAG injection. The influence of surface wettability conditions residue extraction efficiency was also discussed. This work provides insightful understandings of the interfacial forces in mobilizing the residues under immiscible three-phase flow in porous media.