WATER-FLOODING OF FORMATION WITH SURFACTANT OF ULTRA LOW CONCENTRATION Russian patent published in 2016 - IPC E21B43/22 C09K8/584 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to extraction of oil from oil formation. Method of oil recovery from oil-bearing deposit in formation consists in supply of working fluid inside said formation, injection of oleophilic surfactant with concentration of 0.1-100 mg/l of said injected liquid and oil extraction from formation. Method of oil recovery from oil-bearing deposit in formation consists in supply of working fluid inside said formation, injection of oleophilic surfactant concentration, which enables to change the surface tension between oil and water in bottom-hole area of injection well in the formation, but does not change the tension outside of this area, and oil extraction. Method of oil recovery from oil-bearing deposit in formation consists in forcing water inside the said formation, injection of oleophilic surfactant with concentration of 0.1-100 mg/l of said injected water for flooding, said water is injected through injection well in the abovementioned formation, and injection of surfactant - through capollar tube from the source of surfactant to bottom-hole area of the above injection well, injection inside said formation from: biocide, biostat and their combinations, and oil extraction from formation. Invention is developed in depending claims.

EFFECT: increase of efficiency.

20 cl, 1 ex, 4 dwg