Fluid-fluid displacement in mixed-wet porous media

Wettability exerts fundamental control over multiphase flow in porous media, which has been extensively studied in uniform-wet porous media. In contrast, multiphase flow in mixed-wet porous media is less well-understood. We combine microfluidic experiments and pore-scale simulations to study the displacement of oil by water in a mostly oil-wet porous media patterned with discrete water-wet clusters. Our work demonstrates the complex nature of wettability control in mixed-wet porous media, and it presents experimental and numerical platforms upon which further insights can be drawn.