DEVICE FOR CUTTING OUT SECTION OF PIPE IN CASING STRING Russian patent published in 1997 - IPC

FIELD: oil and gas industry. SUBSTANCE: device is used to make easier initial drilling of incline or horizontal bore-hole from vertical well. Device has charge of explosive material located in body and also selection of cumulative cones built in explosive charge. Cumulative cones are located along spiral lines of right-hand and left-hand directions. Distance between adjacent cumulative cones is not over three radii of cone base. When device is in operation, cumulative jets created at points of location of cumulative cones break holes in casing string thus making it weaker. Simultaneously blasting products of explosive charge extend pipe. In result of such combined action on pipe wall, cracks appear at weak points and pipe is destructed along cracks. Section of well at preset location is made free for initial drilling of incline or horizontal well. EFFECT: high efficiency. 1 cl, 5 dwg