METHOD FOR LARGE-VOLUME SELECTIVE ACID TREATMENT OF BOTTOMHOLE FORMATION ZONE IN CARBONATE RESERVOIRS Russian patent published in 2021 - IPC E21B43/27 E21B43/22 E21B33/138 C09K8/74 C09K8/42 

FIELD: oil industry.

SUBSTANCE: invention relates to methods for intensifying oil production from productive formations using selective acid methods of stimulating the bottomhole zone of a formation composed of carbonate rocks or terrigenous rocks with a carbonate content of more than 15%. The method of large-volume selective acid treatment of the bottomhole formation zone in carbonate reservoirs includes injecting into the well a solvent, an acid composition and a diverting liquid with an optimal flow rate and an optimal ratio of the volume of the diverting liquid to the volume of the acid composition. For this, the core is first sampled. The geological and physical characteristics of the formation and the features of the void space are determined. Filtration studies of the core are carried out by pumping the chemicals used through the core samples to determine the type and concentration of the acid composition, types of solvent, diverter and modifying additives. Next, large-volume selective acid treatment of wells is designed using a computer program and acid treatment is carried out by injecting in any sequence with a flow rate of 0.3-2.0 m³ / min of a solvent, an acid composition with a specific volume of 3-20 m³ per 1 meter of the perforated interval and diverting liquid. A mutual solvent or a hydrocarbon solvent is used as the solvent. Inhibited synthetic hydrochloric acid for oil and gas production of brands a, b, c, d, inhibited synthetic modified hydrochloric acid TATOL®-HCl of brands HCl-8/12/2500, HCl-8/12/5000, HCl-24/2500, HCl-24/5000, hydrochloric acid composition TATOL – SKS of brands HCl-15/2500, HCl-15/5000, HCl-24/2500, HCl-24/5000 are used as acid composition. A modified gelled acid composition ZKS-M 1-3 of brands ZKS-1M (a) and ZKS-1M (b) is used as a diverting liquid.

EFFECT: invention is aimed at increasing the efficiency of large-volume selective acid treatment (LSAT) of the bottomhole formation zone, creating a branched network of fluid-conducting channels in the form of a wormhole along the entire perforated thickness of the formation, compatibility of the acid composition with formation fluids, preventing the formation and destruction of sludge complexes.

3 cl, 12 dwg, 3 tbl