Cutter Assembly

Abstract

A cutter module includes a piston and a shear blade. The piston includes at least two movable telescoping elements that are adapted to expand from a first retracted length to a second expanded length. The shear blade is connected to the first piston to sever a tubing in response to the piston expanding from the retracted length to the second expanded length. The shear blade has a cutting edge that has a radius greater than 0.01 inches.

1 . A cutter module to sever a tubing in a well, comprising:
 a piston comprising at least two moveable telescoping elements adapted to expand the piston from a retracted length to an expanded length; and   a shear blade connected to the first piston to sever the tubing in response to the piston expanding from the retracted length to the expanded length,   wherein the shear blade has a cutting edge having a radius greater than 0.01 inches.   
   
   
       2 . The cutter module of  claim 1 , wherein the radius of the cutting edge is approximately 0.06 inches. 
   
   
       3 . The cutter module of  claim 1 , wherein the shear blade comprises S53 stainless steel. 
   
   
       4 . The cutter module of  claim 1 , wherein said at least two moveable telescoping elements comprises a first telescoping element and disposed in a second telescoping element, the cutter module further comprises:
 a retainer to protect the shear blade and retraction of the cutter pistons and disassembly of the cutter module.   
   
   
       5 . The cutter module of  claim 4 , wherein the retainer comprises a backup mechanism to prevent the first telescoping element from coming out of the second telescoping element if the shear blade breaks. 
   
   
       6 . The cutter module of  claim 4 , wherein the retainer is adapted to prevent the shear blade from contacting the second telescoping element. 
   
   
       7 . The cutter module of  claim 4 , wherein the retainer comprises a ring. 
   
   
       8 . The cutter module of  claim 1 , wherein one of said at least two moveable telescoping elements comprises a first telescoping element that telescopes inside a stationary tubular body and a second telescoping element that telescopes inside the first telescoping element. 
   
   
       9 . The cutter module of  claim 1 , further comprising:
 another piston opposable to the first piston;   a second shear blade connected to said another piston,   wherein said another piston is adapted to move in concert with the first piston to cause the first and second shear blades to sever the tubing.   
   
   
       10 . The cutter module of  claim 1 , further comprising:
 a housing to contain the shear blade, the housing comprising a slot to guide the shear blade as the blade extends and retracts.   
   
   
       11 . A method to sever a tubing in a well, the method comprising:
 moving at least two moveable telescoping elements of a first piston to cause the first piston to expand from a first retracted length to a second expanded length; and   driving a first shear blade with the piston to sever the tubing, comprising contacting the tubing with a cutting edge that has a radius greater than 0.01 inches.   
   
   
       12 . The method of  claim 11 , wherein the contacting comprise contacting the tubing with a cutting edge that has a radius of approximately 0.06 inches. 
   
   
       13 . The method of  claim 11 , wherein said at least two movable telescoping elements comprises a first telescoping element disposed to move in a cylinder of a second telescoping element, further comprising:
 providing a retainer inside the cylinder to limit motion of the first telescoping element.   
   
   
       14 . The method of  claim 11 , wherein the act of moving comprises:
 moving one of said at least two moveable telescoping elements inside a stationary tubular body and moving another of said at least two moveable telescoping elements inside said one of said at least two moveable telescoping elements.   
   
   
       15 . The method of  claim 11 , further comprising:
 guiding the shear blade along a slot form in a housing that contains the first shear blade.   
   
   
       16 . A system comprising:
 a blowout preventer stack adapted to seal and contain pressure in a well, the blowout preventer having a passageway through which a tubular string may extend into the well;   a subsea wellhead;   a safety shut-in system having a valve assembly adapted to control flow and adapted to allow tools to be lowered therethrough on tubing; and   a cutter module adapted to be run into the passageway and adapted to allow tools to be lowered into the passageway on tubing, the cutter module comprising:
 a piston comprising at least two moveable telescoping elements adapted to expand the piston from a retracted length to an expanded length; and 
 a shear blade connected to the piston to sever the tubing in response to the piston expanding from the retracted length to the expanded length, wherein the shear blade has a cutting edge having a radius greater than 0.01 inches. 
   
   
   
       17 . A method comprising:
 providing a kit that includes a set of differently-sized spacers and a cutter module assembly having opposable shear blades; and   configuring the spacers to establish different offsets between the shear blades when installed in the cutter module to accommodate different characteristics of tubing to be severed by the cutter module.   
   
   
       18 . The method of  claim 17 , wherein the cutter module assembly comprises at least two movable telescoping elements that comprises a first telescoping element that telescopes inside a stationary tubular body and a second telescoping element that telescopes inside the first telescoping element, the method further comprising:
 configuring the spacers to establish different distances that the first telescoping element travels with respect to the second telescoping element.   
   
   
       19 . The method of  claim 17 , wherein the first telescoping element comprises a shaft that extends to one of the shear blades, the method further comprising:
 configuring each of the spacers to be fitted around the shaft.   
   
   
       20 . An apparatus comprising:
 a cutter module comprising opposable shear blades to sever a tubing in a well; and   differently-sized spacers adapted to be selectively installed in the cutter module to establish different offsets between the shear blades to accommodate different characteristics of the tubing.   
   
   
       21 . The apparatus of  claim 20 , wherein
 the cutter module comprises at least two movable telescoping elements that comprises a first telescoping element that telescopes inside a stationary tubular body and a second telescoping element that telescopes inside the first telescoping element, and   spacers are adapted to establish different distances that the first telescoping element travels with respect to the second telescoping element.   
   
   
       22 . The apparatus of  claim 20 , wherein
 the first telescoping element comprises a shaft that extends to one of the shear blades, and   each of the spacers is adapted to be fitted around the shaft.