Pore- Scale Modeling of Immiscible Displacement In Porous Media: The Effects of Dual Wettability

Many naturally occurring porous media contain different types of grains with different wettabilities, therefore, understanding the effect of wettability heterogeneity on multiphase flow in porous media is important. We investigate the immiscible displacement during imbibition in a dual-wettability porous medium by direct pore -scale modeling. We propose a heterogeneous index (HI) to quantify the wettability heterogeneity. Our simulations on the capillary rise in dual-wettability tubes are compared with theoretical predictions, which verifies the numerical method. Our simulation results on the displacement in the dual-wettability porous media show that the wettability hetero-geneity has a great impact on the fluid distribution, the capillary pressure curve, and the relative permeability curve. With the increase of wettability heterogeneity (HI), more capillary fingers are found during the displacement, the recovery rate of nonwetting fluid decreases, and the capillary pressure and the relative permeability of the wetting fluid decrease.