Rheology of Immiscible Two-phase Flow in Mixed Wet Porous Media: Dynamic Pore Network Model and Capillary Fiber Bundle Model Results

Immiscible two-phase flow in porous media with mixed wet conditions was examined using a capillary fiber bundle model, which is analytically solvable, and dynamic pore network model. The wettability implemented the models by allowing each tube or link to have different wetting angle chosen randomly from given distribution. Both showed that can significant influence on rheology terms of dependence global volumetric rate pressure drop. In for small drops when only fraction tubes were open, it found depended excess drop as power law an exponent equal 3/2 2 depending minimum necessary flow. When all open due high drop, linearly independent wettability. transition region between where most opened, more sensitively distribution function general not simple law. model results also linear large. However, out this limit demonstrated complicated behaviour condition saturation. particular, relating could take values anywhere 1.0 1.8. highest saturations approaching 0.5, also, generally increased difference two fluids larger present network.