The local variations and fluctuations in fluid flow through porous media constantly excite the instabilities of a laboratory or reservoir flood. If the flooding process is dynamically stable, then the fluctuations will decay. Alternatively, the local fluctuations may grow to macroscopic size (viscous fingers). The method of probabilistic simulation includes fluctuations, and provides a computational framework for assessing fluid flow stability. Viscous fingers are produced by unstable floods. Stable floods exhibit smooth solutions despite the ability of the method to naturally incorporate noise. Waterflood (immiscible flood) is examined including the effects of capillary pressure and spatial heterogeneity. The stabilizing effects of relative permeability and of capillary pressure are demonstrated. Correlated permeability variations lead to flow channelling. A low tension flood is demonstrated utilizing a simple modification of a waterflood.
