Cosurfactant blends for oil recovery surfactant system

摘要

A first and second series of aqueous surfactant-cosurfactant-electrolyte systems are prepared at varying electrolyte concentrations using, respectively, a relatively water insoluble cosurfactant and a relatively water soluble cosurfactant. The resulting systems are mixed with oil to be displaced or its equivalent and allowed to equilibrate so as to determine the salinity at which the microemulsion phases formed on said equilibration have approximately equal volumes of oil and water, thus giving the optimal salinity concentration for each surfactant-cosurfactant combination. Similar equilibrations are made using at least one surfactant system which employs a cosurfactant of intermediate water solubility. These systems are then used under the same or similar conditions to displace oil at the optimal salinity for each system and the resulting oil recovery percentage is plotted versus the salinity. Thereafter using the relationship that increasing the more water soluble component of the cosurfactant increases the optimum salinity value and vice versa, a cosurfactant blend is prepared so as to give a system which has an optimum salinity essentially corresponding to the unique salinity.