Method and apparatus for cutting tubular goods

Abstract

A method and apparatus for down-hole cutting of pipe, such as casing, production tubing and other tubular goods. The apparatus has a central mandrel, retractable blades and opposing helical cam sleeves, and can be conveyed into a well and actuated via slickline or other non-conductive wireline. When the apparatus is positioned at a desired down-hole position relative to the pipe to be cut, the blades are extended radially outward to contact the pipe. Axial force applied to the opposing helical cam sleeves transfers torque to the blades which, in turn, rotate and cut the pipe. After the pipe is cut, the blades are retracted, and the apparatus can be retrieved from the well.

1 . A pipe cutting apparatus comprising:
 a) a housing having a central bore extending therethrough;   b) an elongate mandrel having a first end and a second end, slidably disposed in said central bore of said housing;   c) a tapered mounting member connected to said second end of said elongate mandrel, having at least one elongate slot oriented substantially parallel to the longitudinal axis of said tapered mounting member;   d) at least one blade slidably disposed in said at least one elongate slot;   e) a first helical cam member; and   f) a second helical cam member, wherein axial force applied to said first and second cam members causes said at least one blade to rotate.   
     
     
         2 . A pipe cutting apparatus comprising:
 a) a cap member having a central bore extending therethrough;   b) an elongate mandrel having a first end and a second end, slidably disposed in said central bore of cap member;   c) a tapered mounting member connected to said second end of said elongate mandrel, having at least one elongate slot oriented substantially parallel to the longitudinal axis of said tapered mounting member;   d) at least one blade slidably disposed in said at least one elongate slot;   e) an upper cam sleeve having a lower helical surface, connected to said cap; and   f) a lower helical cam sleeve having an upper helical surface, wherein said lower helical surface of said upper cam sleeve rides on the upper helical surface of said lower cam sleeve.   
     
     
         3 . The apparatus of  claim 2 , wherein said central bore extending through said cap member is square, and the portion of said elongate mandrel disposed through said bore has a square cross section. 
     
     
         4 . The apparatus of  claim 2 , further comprising a shear pin disposed through aligned transverse bores in said cap member and elongate mandrel. 
     
     
         5 . The apparatus of  claim 2 , further comprising a blade housing having at least one slot extending therethrough, wherein said blade housing is connected to the bottom of said lower helical cam sleeve, and said at least one blade is aligned with said at least one slot. 
     
     
         6 . The apparatus of  claim 5 , further comprising a base member having a top and a bottom, wherein said bottom forms a bull nose and said top is connected to said blade housing. 
     
     
         7 . The apparatus of  claim 2  further comprising at least one stem guide bushing disposed around said elongate mandrel. 
     
     
         8 . A method for cutting pipe in a well comprising the steps of:
 a) conveying a pipe cutting apparatus inside said pipe to a desired depth;   b) applying axial force to said pipe cutting apparatus;   c) extending at least one blade radially outward from said pipe cutting apparatus to contact said pipe;   d) applying axial force to said pipe cutting apparatus to rotate said at least one blade in a direction substantially perpendicular to the longitudinal axis of said pipe;   e) retracting said at least one blade within said pipe cutting apparatus; and   f) retrieving said pipe cutting apparatus from said well.   
     
     
         9 . The method of  claim 8 , wherein said axial force is applied to said pipe cutting apparatus using jars. 
     
     
         10 . The method of  claim 8 , further comprising the step of shearing a pin prior to extending said at least one blade. 
     
     
         11 . The method of  claim 8 , further comprising the step of shearing a pin prior to rotating said at least one blade.