DE2628526

1520564 Oil recovery MARATHON OIL CO 22 June 1976 [11 Aug 1975] 25905/76 Heading E1F A process for recovering oil comprises injecting into a subterranean formation a miceller dispersion including a hydrocarbon, surfactant, water and a cosurfactant, the latter being in sufficient concentration and having sufficient hydrophilic and/or oleophilic properties to allow the dispersion to solubilize substantially equal volumes of oil and connate water. Preferably the dispersion comprises 4-20% by volume surfactant, 4- 86% by volume hydrocarbon, 10-92% by volume water, 0.01-20% by volume cosurfactant and 0.001-10% by volume electrolyte. The surfactant may be anionic, cationic, nonionic, or mixtures thereof and is preferably a petroleumsulphonate. The hydrocarbon may be crude oil, a fraction thereof, unreacted vehicle oil within the surfactant, synthesised hydrocarbons, or mixtures thereof; and the electrolyte may be water-soluble inorganic salts, inorganic bases, inorganic acids or mixtures thereof and is preferably ammonium sulphate or sulphite, or sodium sulphate or sulphite. The cosurfactant may be an amide, amino compound, ester aldehyde, or ketone and is preferably an alcohol.