INTERNAL RELEASING SPEAR Russian patent published in 1994 - IPC

FIELD: repairs of oil and gas wells. SUBSTANCE: spear has limiting bushing arranged concentrically with casing and connected thereto by shearing members which latter are rigidly connected with casing and limiting bushing, respectively, by plate springs and holding screws which can move along slots of fishing bushing. The latter can interact with inner end of limiting bushing. Outer conical surface of casing is provided with slots for plate springs and holding screws. Thrust screws are rigidly connected with limiting bushing and interact with ends of plate springs when spear is being pulled out. EFFECT: higher reliability of spear due to its facilitated releasing. 4 dwg