Flow visualization experiments and numerical simulations were performed to investigate the combined effects of viscous fingering and permeability heterogeneity in four different two-dimensional glass bead packs. In each model, unstable displacements were performed at three different flowrates and mobility ratios. The experiments were also simulated numerically, using a particle tracking simulator.
In the homogeneous model, fingers grew through the mechanisms of spreading, splitting, shielding and coalescence. Fingering patterns were sensitive to mobility ratio but not to flowrate. Analysis of pressure distributions in and around fingers showed that viscous crossflow drives the finger growth mechanisms.
In the heterogeneous models, flow was largely determined by the patterns of heterogeneity. In all experiments, flow followed high permeability paths seen in the Μ=1 displacements, with viscous fingering effects overlain, despite the fact that permeability contrasts were mild (four-to-one). Simulations yielded finger patterns remarkably similar to those seen in the experiments. Thus, the simulator used represents with reasonable accuracy the physics of finger growth in heterogeneous porous media.