The Role of Immiscible Fingering on the Mechanism of Secondary and Tertiary Polymer Flooding of Viscous Oil

Abstract Immiscible viscous fingering in porous media occurs when a low viscosity fluid displaces significantly more viscous, immiscible resident fluid; for example, the displacement of higher oil with water (where μ o > w ). Classically, this is significant issue during recovery processes, where injected into reservoir to provide pressure support and drive production. In moderate/heavy oil, leads formation strong fingers, bypassed high/early Polymer flooding, viscosified through addition high molecular weight polymers, has often been applied reduce contrast between two fluids. recent years, there development understanding both mechanism by which polymer flooding improves recovery, as well methodologies available directly simulate such processes. One key advance modelling correct oils method accurately model “simple” two-phase (Sorbie Transp Porous Media 135:331–359, 2020). This was achieved first choosing fractional flow then deriving maximum mobility relative permeability functions from this. It proposed that central fingering/viscous crossflow mechanism, summary given paper. work seeks validate experimentally moderately ( = 84 mPa.s at 31 °C; 0.81 mPa.s; thus, / ) ~ 104) performing series carefully monitored core floods. The results these experiments are simulated establish potential our modified simulation approach capture process (Sorbie, et al., Both secondary tertiary presented compared waterflood baselines, have established each system. production, cut differential matched using commercial numerical simulator, but new “fractional flow” derived permeabilities. use even (80% after 0.5 PV injection), showed impact on recovery; bringing forward time injection modes—a further 13–16% OOIP. Each flood simulator excellent agreement all experimental cases. simulations allowed quantitative visualisation finger propagation banking connate flooding. Evidence bank forming front slug also observed, line mechanism. provides validation flooding’s direct methodology Sorbie al. (Transp show reservoirs.