PROCESS OF DEEP PERFORATION OF CASED WELLS Russian patent published in 2002 - IPC

FIELD: oil and gas industry, uncovering of producing oil and gas horizons. SUBSTANCE: process of deep perforation of cased wells includes sinking of drill unit with cutting tool on end of flexible shaft on string of pipes into well, fixing of unit in shaft of well in specified interval and drilling of perforation channels by cutting tool imparting it with rotation and axial movement by supply of working fluid to mechanisms of rotation of flexible shaft and axial movement. In agreement with invention perforation channels are drilled simultaneously with their flushing by supply of working fluid on to cutting tool and into zone of its contact with drilled-out medium. Flushing fluid is used in the capacity of this fluid. It is pumped by ground pump in turn through string of pipes and mechanism rotating flexible shaft. Hydraulic downhole motor and race communicating with output shaft of the latter are used as this shaft. EFFECT: increased perforation efficiency thanks to raised speed of channel drilling, reduced wear-out of cutting tool and preservation of reservoir properties of stratum. 3 cl, 1 dwg