Miscible, vertical network model 2-D simulations of two-phase flow displacements in porous media

A pore-level network model was used to study miscible, vertical, two-phase fluid displacements. Gravitationally unstable and stable flow configurations were explored with the Darcy–Rayleigh number (G) for a number of viscosity ratios (M). Simulations were compared with experimental results for corresponding values of G and M using interfacial width and breakthrough saturation as comparison criteria. Good agreement between the model and experimental results was observed. For gravitationally stable flows, a critical value of G, Gc≈−0.02, was obtained from simulation results compared to an experimental value of Gc≈−0.017 found in the current literature. The transition from gravitationally stable to unstable flow was shown by decreased interfacial stability resulting in dramatically higher values of interfacial width (simulation) and dispersivity (experimental). Breakthrough saturations for gravitationally stable experimental flow configurations differed only a small amount from simulation results when considering the large length-to-width ratios of the experimental cores used for comparison.