Patent ID: 6453997
Filing Date: 2002-09-24
Classification: E21B

Abstract:
A fishing assembly for use in a well, comprising:a string of conduit for lowering into the well; a tubular housing, the housing having a longitudinal axis and a hammer anvil interface; a chamber in the housing having an entry port that communicates with a passage extending through the conduit and an exhaust port leading to an exterior of the housing; a mandrel carried in the housing, the mandrel and the housing being axially moveable relative to each other, the mandrel having a hammer anvil interface that is positioned for cooperative engagement with the hammer anvil interface of the housing, the housing and the mandrel being carried by the conduit with one of the mandrel and the housing adapted to be connected to a stuck object in the well; a piston carried in the chamber of the housing for axial movement relative to the housing and the mandrel; a firing member in the housing that is engageable by the piston when the piston has moved toward the firing member a selected distance, and wherein after the piston engages the firing member, the firing member applies a restrictive load against movement of the piston in an opposite direction; a directional valve in communication with the entry port of the chamber in the housing, the directional valve directing flow of a fluid being pumped down the conduit to the chamber on one side of the piston to move the piston in the opposite direction, while the exhaust port of the chamber vents the fluid on the opposite side of the piston to the exterior, wherein once the pressure of the fluid on the piston reaches a sufficient level due to the restrictive load, the housing and mandrel will move relative to each other to a cocked position, separating their respective hammer anvil interfaces from each other and elastically deforming the conduit in the well, thereby storing energy; and wherein once the housing and the mandrel reach the cocked position, the firing member subsequently releases the piston, which allows the energy stored in the conduit to rapidly move the hammer anvil interfaces of the housing and the mandrel into engagement with each other.