Experimental Investigation of the Effect of Oil on Foam Two Regimes
Simulating foam EOR processes still faces many challenges owing to limited data. One of the big challenges restricting effective prediction of foam performance in the presence of oil is which of the two regimes is affected by oil. A model study (Tang et al. 2016), using the widely used STARS foam model, suggests that oil in wet-foam model affects only the low-quality regime, while oil in dryout model impacts only the high-quality regime. Experimental studies therefore are carried out to gather lab data on the effect of oil on the two regimes and to see if these models can reliably represent the effect of oil on foam in contact with oil in porous media. Our results show that in the presence of oil, the two regimes, central to understanding of foam without oil, still appear. Oil shifts the two regimes to lower pressure gradient, with the high-quality regime more vulnerable to oil. Then, foam parameters in the same model are fitted to the experimental data. When oil effect is strong enough, one must fit the limiting water saturation (Sw* ) to each ∇p contour separately and exclude shear-thinning in the low-quality regime to give a good match to data. The experimental results and model fit together suggest that oil affects the high-quality regime by increasing Sw* and impacts the low-quality regime by reducing mobility reduction factor fmmob. However, none of the current foam simulation models can capture the upward-tilting ∇p contours in the absence of oil in the low-quality regime. In future, I will attempt to capture this behaviour by introducing a function related to water superficial velocity into the current foam models.