MULTISTAGE SOLVENT EXTRACTION METHOD FOR HIGH-DENSITY OIL POOLS Russian patent published in 2015 - IPC E21B43/22 

FIELD: oil and gas industry.

SUBSTANCE: group of inventions is related to production of heavy hydrocarbons. In the in situ multistage solvent extraction method of heavy oil from oil pools at first liquids and gases are extracted from zones of contact with heavy oil in order to increase interfacial area of unextracted heavy oil subject to contact with solvent. Then solvent is injected in the form of steam to the above zones in order to increase pressure in the pool up to accumulation of sufficient quantity of solvent in the form of liquid to ensure contact with enlarged interfacial surface of heavy oil. Then the pool is isolated for the period sufficient to ensure diffusion of solvent to unextracted oil through the interfacial surface at ageing stage so that the mixture of solvent and oil with low viscosity is obtained. One or more parameters of the pool are measured to determine the degree of unextracted oil liquefaction in the pool by solvent. Oil extraction from the pool is commenced by gravity drainage when viscosity of oil becomes rather low to flow through the pool to the production well.

EFFECT: maximising liquefaction of heavy oil and maximising its extraction as a result.

19 cl, 11 dwg