METHOD AND DEVICE FOR SECONDARY FORMATION PENETRATION

FIELD: oil production device, particularly secondary opening of productive bed closed with casing pipes with the used of high-velocity drilling mud jets. ^ SUBSTANCE: method involves creating orifices in casing pipe wall and in cement sheath; performing hydraulic formation perforation along with injecting working fluid through formation perforation device suspended by pipes. Windows or slots in casing pipe wall are cut in single trip. Device is provided with pipe cutter or slot perforator having milling tool with sliding cutting members and valve for milling tool isolation from injected liquid flow. The hydraulic perforation operation is performed through windows cut in the casing pipe with the use of pipe cutter or through slots cut by slot perforator. The bore is formed by high-velocity jets, wherein at beginning the first bore is created. Time of the first bore creation is 20-30% of total hydraulic perforation operation time. Then place of contact between jet and rock is changed due to injection pressure reduction and due to casing pipe deformation. The next bore is formed so that reflected liquid flow passes into the first bore and the second bore depth may be increased by jet having lesser obstruction. Device comprises body, hydraulic assembly made as hollow case with nozzles built in radial bores thereof. Device is also provided with pipe cutter or slot perforator with milling tool having sliding cutting members and valve system including upper and lower valves. Lower valve is located between the milling tool and hydraulic monitor unit and is adapted to isolate the milling tool from injected liquid flow and to provide flow passage through the nozzles to perform hydraulic formation penetration. The upper valve is made in piston and may supply liquid from pipes into the well during tool lifting. ^ EFFECT: increased depth of perforation bores and reduced perforation time. ^ 3 cl, 1 dwg