Mathematical modelling of enhanced oil recovery by alkali solutions in the presence of cosurfactant and polymer

Islam, M.R. and Chakma, A., 1991. Mathematical modelling of enhanced oil recovery by alkali solutions in the presence of cosurfactant and polymer. J. Pet. Sci. Eng., 5: 105-126. A mathematical model describing oil recovery by alkali solutions in the presence of cosurfactants and polymers is presented. According to previously published experimental results, oil recovery is sensitive to transient interfacial tension (IFT) particularly near ultra low IFT values. Unlike previously published models, the present work accounts for the transient interfacial tension and nonequilibrium mass transfer phenomena. Adsorption at the solid/liquid interface has been described by a surface excess model. Over thirty simulation runs have been performed to investigate the effects of alkali, cosurfactant and polymer concentrations, chemical slug size and dynamic IFT on oil recovery. The model was found to be sensitive to initial alkali, cosurfactant and polymer concentrations. For the cases studied, a 0.1% alkali, 0.1% polymer and 0.01% cosurfactant solution yielded the highest oil recovery. The presence of optimal concentration was recognized for cosurfactant. This optimum behaviour was attributed to dynamic interfacial tensions.