Numerical investigation of fracture-rock matrix ensemble saturation functions and their dependence on wettability

The obtained fracture-matrix ensemble relative permeability curves show that ultimate recovery is 2-3 times higher in the water-wet than in the oil-wet case. With increasing wetting angle, counter-current-imbibition (CCI) rate decreases because the capillary pressure difference between small fractures that contribute the most to the fracture-matrix transfer area is very small. As the rock becomes oil wet, ensemble relative permeability curves steepen and matrix imbibition proceeds only over a very narrow saturation range.