METHOD OF GASOCYCLIC INJECTION OF LIQUID CARBON DIOXIDE UNDER SUPERCRITICAL CONDITIONS IN THE OIL PRODUCING WELL Russian patent published in 2018 - IPC E21B43/16 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to the production of hard-to-recover oil and gas condensate reserves by means of carbon dioxide. Method involves injecting liquid carbon dioxide into the production well. Before injecting liquid carbon dioxide into the well, a first rim of the mixture of the "Delta ARPHDI" composition is injected into the well, containing a mixture of secondary oil products of pyrolysis and hydrocarbon crude processing processes, and dimethyl carbonate in equal volume ratios in an amount of not less than 5–20 % of the daily volume of produced fluid of the well. Then liquid carbon dioxide is injected at a temperature of at least T_crit=31.1 °C and a pressure of at least P_crit=7.38 MPa for supercritical conditions in a formation. Then a second rim of the mixture of the "Delta ARPHDI" composition ratios in an amount of not less than 5–20 % of the daily volume of the produced fluid of the well. Number of injection cycles in this sequence in the production well must be not less than 3. Impregnation of the well zone is carried out. Then, oil is extracted from the same production well.

EFFECT: increase in the efficiency of extraction of residual oil reserves by using carbon dioxide geologically accumulated during technological processes.

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