Chemical cutting apparatus

Abstract

An improved chemical cutting apparatus for cutting objects in well bores such as, for example, tubing in the bore of an oil or gas well. The apparatus is properly positioned relative to the object to be cut by means of a casing collar locator, and an igniter is fired which in turn activates a gas generator. Pressure from the gas generator axially displaces a slidable piston having suitable anchor means connected thereto. Movement of the piston causes the anchor means to move into contact with the object to be cut, thereby anchoring the apparatus relative to such object. Pressure generated in the gas generator is communicated through a passageway in the slidable piston and forces a chemical cutting agent into a chamber containing a reactant. The reaction of the chemical cutting agent and reactant increases the pressure and temperature within the chamber thereby displacing along the axis a second slidable piston. Movement of the second slidable piston exposes radial exhaust orifices thereby allowing the reacting elements in the chamber to escape with great velocity and to contact the object to be cut in incendiary fashion. The improvement according to the present invention resides in the provision of pressure relief means intermediate the gas generator and the chemical cutting agent for diverting a portion of the gas away from the chemical cutting agent so as to reduce the likelihood of release of the chemical cutting agent in the event the apparatus is mishandled or malfunctions.