Evaluation of surfactant blends for enhanced oil recovery through activity maps

Abstract

Better use of already exploited oil reservoirs using Enhanced Oil Recovery techniques is becoming essential. The use of surfactant blends is a common approach when individual surfactants are not effective. However, defining the optimum conditions for application becomes very challenging due to the number of variables involved in specific cases. In this work, blends of dioctyl sulfosuccinate sodium salt with Akypo LF2 and two surfactant ionic liquids (1-decyl-3-methylimidazolium chloride and 1-dodecyl-3-methylimidazolium bromide) were evaluated for oil recovery. Activity maps, representations of the phase behavior of the surfactants as a function of blend ratio, salinity and temperature, were found to be useful tools to describe conditions leading to Winsor type III systems. Among the blends studied, mixtures with Akypo LF2 were found of interest for application at low temperatures, showing interfacial tensions close to 0.01 mN/m in a wide range of salinity concentrations. In the case of blends with ionic liquids, even though they led to more promising solubilization parameters, the high sensitivity of these mixtures to blend ratio changes discourages, in principle, their use for practical applications.