DESORBENTS FOR ENHANCED OIL RECOVERY Russian patent published in 2017 - IPC C09K8/584 E21B43/22 

FIELD: oil industry.

SUBSTANCE: present invention relates to improvement of oil recovery from underground formations. Use of at least one nonionic surfactant – NIS, selected from compounds of formula R-O-(-CH₂-CH(-CH₃)-O-)_m-(-CH₂-CH₂-O-)_n-H, where R is a dodecyl group -(CH₂)₁₁-(CH₃), m is an integer from 0 to 20; n is a number greater than m and ranging from 5 to 40, to prevent retention of anionic surfactant in oil reservoir, in particular, in a carbonated or clay reservoir, said NIS is used as at least as an agent preventing retention of anionic surfactant introduced in combination with it, and/or as a protective agent, introduced before introducing anionic surfactant, and/or for desorption of anionic surfactant, previously contained in reservoir. Method for improved oil recovery from underground formation, including said application, comprising steps of: injecting into said underground formation via at least one injection well, a fluid comprising at least an aqueous medium, an anionic surfactant and optionally an anionic cosurfactant, then injecting fluid containing said NIS and said fluid moving oil coming from an underground formation, extracted by means of at least one agent. Invention is developed in subclaims.

EFFECT: technical result is high efficiency of oil recovery.

13 cl, 4 tbl, 4 ex