| 摘要 |
FIELD: oil and gas industry.SUBSTANCE: invention is intended for screwing-off and destruction of shoe during installation in wells of expanded columns. Device includes a housing with flushing channel, mounted rigidly on it cutting mandrel with communicated with flushing channel central and working holes, equipped from below with cutting elements, arranged radially and regularly relative to rotation axis, and channels for removal of chips in form of radial expanding to periphery end channels, arranged in cutting elements and communicated with flushing channel process openings, which are located closer to centre of rotation of mandrel, and with longitudinal grooves-slots on cylindrical surface of mandrel. Housing is equipped with annular extension with a chamfer on side of mandrel and longitudinal grooves are connected to radial and tangential planes. Angle between cutting elements in range of 110°-140° and rear angle of cutting elements in range of 8°-20° are selected depending on material of shoe. Holes of mandrel are equipped with water jet nozzles. Expansion with chamfer is made from material harder than that of reamed string. Inserts on chamfer are made of hard alloy. Radial channels in cutting elements diverge at an angle equal to that between rows of cutting elements. In depth of radial channels diverge from centre to periphery.EFFECT: higher efficiency due to reduced time for drilling of shoe, axial load, torque.1 cl, 1 dwg |
