Patent ID: 6109373
Filing Date: 2000-08-29
Classification: E21B

Abstract:
An overshot assembly that is movable axially inwardly in a drill string and retractable axially outwardly through the drill string by a wire line when applying a retracting force and being coupleable to an overshot coupling device of a drilling tool that is axially movable in the drill string, comprising an axially elongated overshot head subassembly having means for releaseably coupling to the overshot coupling device and an axially elongated opposite outer end portion, an axially elongated jar subassembly having an axially elongated inner end portion and axially opposite means for having the wire line connected thereto, at least one of the head subassembly outer end portion and the jar subassembly inner end portion having an axially elongated cable receptive tubular portion opening toward the other end portion of the respective one of the head subassembly and the jar subassembly each of the head subassembly and the jar subassembly having a central axis, and an elongated cable subassembly arcuately bendable through an angle that the central axes extend coextensively relative to one another, to one that the central axes extend at an included angle of about 135 to 90 degrees relative to one another and bendable back to extend at an angle that the central axes extend substantially coextensive relative to one another without any substantial permanent deformation, the cable subassembly including an axially elongated cable having a first end portion, a second end portion and an axially elongated intermediate portion extending between and joined to the cable first and second end portions, first cable mounting means for connecting one of cable end portions to the jar subassembly inner end portion, second cable mounting means for connecting the other of the cable end portions to the head subassembly outer end portion, means joined to the first cable end portion and abuttable against the adjacent cable mounting means to limit the movement of the cable in an axial direction toward the cable second end portion, means joined to the second cable end portion for limiting the movement of the cable in a direction toward the cable first end portion, one of the cable mounting means being mounted to the tubular portion and having the cable slidably extendable therethrough to have at least a major portion of the axial length of the cable, including the first cable end portion, extendable into the tubular portion to permit the jar subassembly being movable relative to the head subassembly between an axially spread apart first position and an adjacent abutting second position to deliver a hammering blow to the head subassembly, the cable being of a flexibility to permit the cable intermediate portion being repeatedly arcuately curved from a position the central axes extend at an angle of less than about 135 degrees relative to one another to a position the central axes extend substantially coextensive relative to one another and of a rigidity to permit the cable first end portion being reciprocated in the tubular portion upon the application of a vertical outwardly retracting force being applied to the jar subassembly and releasing the retracting force.