New insights on the complex dynamics of two-phase flow in porous media under intermediate-wet conditions

Multiphase flow in porous media is important in a number of environmental and industrial applications
such as soil remediation, CO2 sequestration, and enhanced oil recovery. Wetting properties control
flow of immiscible fluids in porous media and fluids distribution in the pore space. In contrast to the
strong and weak wet conditions, pore-scale physics of immiscible displacement under intermediatewet conditions is less understood. This study reports the results of a series of two-dimensional highresolution direct numerical simulations with the aim of understanding the pore-scale dynamics of twophase immiscible fluid flow under intermediate-wet conditions. Our results show that for intermediatewet porous media, pore geometry has a strong influence on interface dynamics, leading to co-existence
of concave and convex interfaces. Intermediate wettability leads to various interfacial movements
which are not identified under imbibition or drainage conditions. These pore-scale events significantly
influence macro-scale flow behaviour causing the counter-intuitive decline in recovery of the defending
fluid from weak imbibition to intermediate-wet conditions.