ACID TREATMENT METHOD OF OPEN HORIZONTAL SHAFT OF WELLS Russian patent published in 2021 - IPC E21B43/27 E21B37/06 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil industry and, in particular, to methods for intensification of oil production from productive carbonate formations opened by wells with open horizontal shafts. Method comprises separating formation treatment intervals. Tubing string is lowered and equipped with a jet nozzle with a seat from below for a stop element thrown to the tubing string from the well mouth. Jet nozzle is installed opposite to the interval of acid treatment closest to the bottomhole. From the well mouth, the shutoff element is dropped into the tubing string. Process liquid is brought to the mounting seat of the jet nozzle. Acid treatment is carried out. At the end of the acid treatment, the jet nozzle is removed to the surface. Geophysical investigations in an open horizontal borehole are used to identify intervals with low and high permeabilities. Jet nozzle is equipped above seating seat with two rows of holes with possibility of acid pumping both through one row of holes, and simultaneously through two rows of holes. Acid treatment is carried out by moving the pipe string from the bottomhole to the mouth in a mode of jetting with formation of longitudinal planes in the bottomhole formation zone - opposite radial holes of the jet nozzle along the entire length of the open horizontal shaft. In intervals with high permeability treatment is performed through one row of jet nozzle under pressure up to 10.0 to 19.99 MPa, created by one pump unit. In intervals of open horizontal shaft with low permeability treatment is performed through two rows of jet nozzle under pressure from 20.0 to 35.0 MPa, created by two pump units. During movement of tubing string in direction from wellhead to well bottom after lifting of tubing string each time acid from tubing string through formed longitudinal cavities in bottom-hole zone of formation is forced into productive formation. At the end of acid treatment products of reaction of acid with rocks of productive formation are removed. Then the well is developed by swabbing.

EFFECT: improving efficiency and quality of acid treatment of open horizontal shaft, as well as exclusion of acid discharge to wellhead and improvement of acid work safety, reduction of processing duration, open horizontal borehole.

1 cl, 5 dwg