Effect of surfactant micelle shape transition on the microemulsion viscosity and its application in enhanced oil recovery processes

摘要

Surfactants have already been distinguished as having commercial application in oil industry especially Enhanced Oil Recovery (EOR) processes. During EOR processes, surfactants or a mixture of surfactants and polymers are injected into the reservoir to reduce the interfacial tension of microemulsion typically from about 30 dyn/cm to 10~(-3) dyn/cm. Polymers are added to reduce the mobility by increasing the viscosity of the solution. The geometricalmicelle shape of a number of surfactantsmight change from spherical to cylindrical above a concentration generally known as criticalmicelle concentration. Although previous studies haven't considered the effect of surfactants on solution viscosity, this shape transition could significantly affect the viscosity of solution. In this study, a previously developed model is used in conjunction with experimental data to investigate the effect of surfactant and salt concentrations on the micelle shape transition. It is found that for some ranges of surfactant and salt concentrations; shape transition from spherical to cylindrical causes a considerable increase in the viscosity of dodecyl ammoniumchloride (DeAC) solution. Based on the results of this study, a number of surfactants could be used for simultaneous modification of the IFT and viscosity of themicroemulsion rather than using both polymers and surfactant.