METHOD OF ACID HYDRAULIC FRACTURING IN REVERSE SEQUENCE FOR CARBONATE FORMATIONS Russian patent published in 2024 - IPC E21B43/27 

FIELD: oil, gas and coke-chemical industry; mining.

SUBSTANCE: invention relates to oil production and can be used in treating a productive formation for increasing oil recovery. Disclosed is a method for acid fracturing in reverse sequence for carbonate reservoirs, which includes alternate injection of high-viscosity acidic fluid and low-viscosity acidic fluid in multistage mode. Method includes performing the following steps: S1 — based on the geological characteristics of the structure of the target formation, a hydraulic fracturing simulator is used to calculate the geometrical size of the hydraulic fracture formed under conditions of injecting a preliminary fluid, and average temperature inside hydraulic fracture; S2 — geometrical dimensions of hydraulic fracture determined at step S1 are used to calculate viscosity coefficient and amount of injected acid in high-viscosity acidic liquid and low-viscosity acidic liquid; S3 — based on the average temperature in the hydraulic fracture determined at the stage S1 during laboratory rheological tests of the acidic liquid and based on the viscosity coefficient of the high-viscosity acidic liquid and the low-viscosity acidic liquid determined at step S2, determining the acidic liquid system corresponding to the viscosity coefficient of the acid introduced in the reverse sequence; and S4 — based on the acid fluid system determined at step S3 and the amount of injected acid determined at step S2, acid fracturing is performed.

EFFECT: increased diverting capacity of cracks due to formation of stable viscous tongues and improved effect of non-uniform etching.

5 cl, 1 dwg, 3 tbl