METHOD OF FORMATION HYDRAULIC FRACTURING FROM CASED WELL AND DEVICE FOR METHOD EMBODIMENT Russian patent published in 2002 - IPC

FIELD: oil producing industry. SUBSTANCE: method includes determination under stand conditions of working fluid pressure required for provision of minimum permissible rate of deepening of perforation channel in formation during hydraulic perforation; determination of rock strength for single-axis compression; setting of depth of channel perforation and time for channel formation; cutting the first holes in casing string with partial opening of cement stone by high-pressure jets of working fluid; cutting near the first holes next holes in casing string, cement stone and formation rock to preset depth; formation of perforation channels in formation rock by making deep slots with use of working fluid supplied until free coming of reflected flow to wellbore through the first or previous holes. Outlet edges of giant nozzles are kept at a distance of 3-4 diameters of giant nozzle outlet channel from internal surface of casing string during perforation. Device for method embodiment includes pipe string with hydroperforator at its lower end. Device body lower part is plugged. Installed in side walls are giant nozzles with through channels. Through channel of each giant nozzle is made of three joining with one another parts: inlet, middle and outlet. Outlet part is cylindrical in shape with length equaling its diameter. Channel middle part is made in the form of cone with its taper angle of 5 to 10 deg and length equaling 2 to 2.5 diameters of cylindrical channel of its outlet part. Inlet part is made in the form of cone with taper angle exceeding that of middle part at least by 1.5 times. EFFECT: higher efficiency of formation hydraulic fracturing at low pressures of hydrofrac fluid, reduced cost of operations and increased service life of equipment. 4 cl, 2 dwg