SURFACTANT OIL RECOVERY PROCESS

An aqueous solution comprising an alkalinity agent such as sodium hydroxide, a water soluble guanidine salt such as guanidine hydrochloride and an anionic surfactant such as an aliphatic sulfate, specifically dodecyl sulfate or cetyl sulfate, or a water soluble salt of an unsaturated aliphatic monobasic carboxylic acid, such as sodium oleate, is injected into a subterranean petroleum containing formation, followed by the injection of water to displace a surfactant-guanidine solution through the formation. A plurality of benefits result from the use of this combination, including increased injection solution viscosity for mobility ratio improvement, inhibition of clay swelling which causes formation permeability damage, and improved salt tolerance of the surfactant solution so that surfactant-emulsion flooding may be carried out in subterranean petroleum containing formations whose formation water salinity is as high as 4 percent.