METHOD FOR MULTI-STAGE HYDRAULIC FRACTURING IN WELL WITH HORIZONTAL TERMINATION Russian patent published in 2020 - IPC E21B43/26 

FIELD: oil, gas and coke-chemical industries.

SUBSTANCE: invention relates to oil and gas industry, particularly, to implementation of interval multi-stage hydraulic fracturing in wells with horizontal termination. Method of multistage hydraulic fracturing in well with horizontal termination includes lowering of hydraulic fracturing assembly with adapter on tubing string to finished and cased well with horizontal section. Structure of assembly comprises packer of hydraulic action, upper and lower anchor, there are two folding check valves inside the assembly. Adapter stem passes through the packer and has a seat at the end. After the assembly is lowered to the preset interval, the ball is dropped and pumped to the seat seat attached to the adapter stem part by shear pins. Further, excessive pressure is created in the tubing string, due to which the pins are cut off in the packer of hydraulic action; anchors are moved, which in turn deforms the packer collar. Cuff deformation promotes tight disconnection of intervals before and after assembly. After that pressure is released in the tubing string and stretching is no more than 2 tf. Pins are cut in the seat of the adapter stem section. Packer is unloaded to packer of not less than 5 tons and stem part of adapter moves downwards. Ball and landing seat fall out of barrel part of adapter. Further, fluid-fracturing is pumped into the tubing string, the liquid fills part of the casing string below the packer and process cracks are formed in the productive formation owing to excessive pressure. Further, the tubing string is lifted, the stem part of the adapter comes out of the packer, which helps to close the flap check valves. Thus, interval hydraulic fracturing of formation is performed with subsequent shutdown of interval and pressure retention under packer. Further, work on hydraulic fracturing of the formation in the required amount is performed with leaving the packers in the well shaft. After performing the required number of intervals of hydraulic fracturing in horizontal section on flexible tube, cutters are lowered, drilling of remaining after fracturing is performed with washing of metal and rubber chips on surface. At the end of operations, the well is developed, downhole equipment is lowered and brought to the mode.

EFFECT: technical result consists in development of hydraulic fracturing, which enables to conduct interval hydraulic fracturing using a system of folding check valves.

1 cl, 7 dwg