Gravity-destabilized nonwetting phase invasion in macroheterogeneous porous media: Near-pore-scale macro modified invasion percolation simulation of experiments

We reconceptualize "macro" modified invasion percolation (MMIP) at the near pore (NP) scale and apply it to simulate the nonwetting phase invasion experiments of Glass et al. [2000] conducted in macroheterogeneous porous media. For experiments where viscous forces were nonnegligible, we redefine the total pore filling pressure to include viscous losses within the invading phase as well as the viscous influence to decrease randomness imposed by capillary forces at the front. NP MMIP exhibits the complex invasion order seen experimentally with characteristic alternations between periods of gravity-stabilized and destabilized invasion growth controlled by capillary barriers. The breaching of these barriers and subsequent pore-scale fingering of the nonwetting phase is represented extremely well, as is the saturation field evolution and total volume invaded.