1. n. [Enhanced Oil Recovery]

A thermodynamically stable emulsion consisting of a mixture of oil, water and surfactant. In contrast to a simple emulsion formed under shear, a microemulsion is a minimum energy state. It does not require an input of energy into the system to form; instead, it forms spontaneously. Depending on the structure of the surfactant and the presence or absence of cosurfactant, an oil-in-water system (Winsor Type I), a water-in-oil system (Winsor Type II) or a bicontinuous system (Winsor Type III) may form. Various structures of micelles and reverse micelles are possible, ranging from spherical through cylindrical to lamellar. A typical microemulsion will have micelle diameters in the range of 3 to 20 nm.

See: emulsion,  micelle,  Winsor phase behavior