Modeling and simulation studies of foam processes in improved oil recovery and acid-diversions
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Foam has application in gas diversion in improved oil recovery, acid diversion in well stimulation, and environmental remediations. Successful foam application in these processes requires predictive foam modeling. In this study, a foam simulator based on the "fixed-Pc*" model is implemented into a chemicalflood reservoir simulator, UTCHEM, and successfully validated against an analytical method. This foam simulator can describe foam flow in both low- and high-quality regimes. Two numerical artifacts resulting from numerical dispersion of the surfactant front are examined; both can be controlled by using a higherorder numerical scheme and grid refinement. A study of the effect of surfactant on foam strength and propagation reinforces Zeilinger’s (1996) finding that, in the absence of dispersion, the foam front propagates as an indifferent wave; independent of how foam strength depends on surfactant concentration.. Two-dimensional simulations of foam flow in adjacent layers show that capillary-crossflow does weaken foam in the high-permeability layer, but it does not fatally hurt sweep efficiency between adjacent layers. Viscous cross-flow gives an even frontal advance of foam in all cases we examined. A gas-trapping model for foam is implemented into UTCHEM. The model fits steady-state foam mobility and the non-Newtonian rheology of liquid injected after foam. When applied to model dynamic coreflood data, the simulator qualitatively fits the transition period between foam and liquid injection in laboratory corefloods.