Controlled delivery and release of surfactant for enhanced oil recovery by nanodroplets

Chemical-based oil recovery method has promising applications but suffers the problem of large quantity of chemical loss inside the reservoir. This work proposes an innovative concept of using nanodroplets as carriers for surfactants/polymers and control their release inside porous media to increase oil recovery in water-wet reservoirs. Comparing to conventional surfactant flooding, the proposed concept could not only reduce the adsorption of surfactant on rock surface, but also ease the problem of unstable surfactant slug injection and release surfactant slowly inside a reservoir. The oil recovery efficiency was evaluated for micelles and nanodroplet forms of surfactants blend in a customized core flooding system and differential pressures were monitored to evaluate the injection stability of flooding fluids. The retention of surfactants was analyzed by high-performance liquid chromatography after the core flooding tests. The experiments confirm the advantages of nanodroplets as surfactant carriers. The results show that the new approach promoted tertiary oil recovery around ∼8%, while reducing the adsorption of surfactants almost half on the surface of sandstone rock comparing to the micelle form.