EXTRACTION METHOD OF HARD-TO-RECOVER OIL RESERVES Russian patent published in 2020 - IPC E21B43/24 E21B43/22 E21B49/00 C09K8/592 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to the oil-producing industry. Method of extracting hard-to-recover oil reserves involves preliminary investigation of ultraviscous oil composition and selection of solvent, pumping into the well of a solvent, which is a mixture of hydrocarbons of the aliphatic and aromatic series, pumping of steam and subsequent extraction of the product. During preliminary investigations of ultraviscous oil composition, total content of resin-asphaltene substances in oil is determined on the basis of which solvent is selected. Selected solvent with ultraviscous oil is tested for compatibility. Steam injection is performed. If total content of resinous asphaltene substances in ultraviscous oil exceeds 15 wt%, then toluene 10–80 wt% is added to said solvent depending on content of resinous asphaltene substances in ultraviscous oil and pumping is performed. After pumping of solvent steam is pumped again. Well is impregnated for 7 days.

EFFECT: raised efficiency of extraction of hard-to-recover reserves of ultraviscous oil from formations of small thickness, exclusion of falling out of resin-asphaltene substances in formation with simultaneous reduction of material costs.

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