METHOD FOR HYDRAULIC FRACTURING OF A FORMATION Russian patent published in 2020 - IPC E21B43/26 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to methods for intensifying oil recovery from carbonate reservoirs by performing acid fracturing and can be used to increase fluid and oil inflow to wells exploiting high water-flooded carbonate formations. Method consists in lowering the tubing string to the zone of hydraulic fracturing of the carbonate formation, sealing the annular space with a packer and pumping process fluids into the formation in three stages. At first step, formation is treated with self-deflecting acid composition. Said composition is pumped continuously, wherein injection pressure must not exceed formation hydraulic pressure. Due to natural gelation of self-deflecting acidic composition (SDAC) there is decreased intake capacity of productive formation and gradual increase of pressure is observed. On completion of SDAC gelation, the second stage of the process begins, in which hydraulic fracturing of the formation is carried out by continuing injection of SDAC. As a result of hydraulic fracturing in the oil-saturated zone of the carbonate formation, a system of secondary cracks is formed. This procedure is repeated at the third stage of action on the formation in order to create tertiary cracks and filtration channels in the oil-saturated zone of the formation.

EFFECT: technical result consists in reduction of time of action on productive formation, in reduction of time of development of well and formation after treatment, as well as in reduction of water fraction in extracted product and in increase of oil recovery under existing system of maintaining formation pressure.

1 cl, 1 dwg