Patent ID: 6564885
Filing Date: 2003-05-20
Classification: E21B

Abstract:
A drilling apparatus, which is fluidly propellable axially inwardly in a drill string from the drill string outer end to a position to couple to a drilling tool at the drill string bit end and retractable axially outwardly by a wire line, comprising:(a) an axially elongated overshot main body having an outer end portion, (b) a pair of pulling dogs having axial outer end portions, axial intermediate portions and axial inner jaws for releasably coupling to the drilling tool, (c) means for pivotally mounting the pulling dogs to the main body for movement between a drill tool coupling position and an overshot release position, (d) an axially elongated overshot member having an outer end portion, an axial intermediate portion and an inner end portion mounted to the main body outer end portion to extend axially outwardly thereof, (e) annular means mounted to the axial intermediate portion of the overshot member for forming a fluid seal between the drill string and the overshot member, (f) at least one of the overshot member and the main body having a fluid bypass channel to bypass the means for forming a fluid seal, (g) at least one of the overshot member and the main body having a valve seat through which the bypass channel extends, (h) a valve member mounted to at least one of the main body and the overshot member for limited movement between a closed position blocking fluid flowing through the valve seat and axially outwardly through the bypass channel and an open position, and (i) means for resiliently urging the valve member to its closed position while permitting the valve member being moved to its open position by fluid under pressure being exerted on the valve member in an inward direction.