Pipe perforating apparatus and method

Abstract

A method and apparatus for perforating pipe from its interior, and in particular for perforating plastic well casing in situ. A linear actuator drives a claw-shaped bit. Linear motion of the cylinder is converted to a pivoting of the bit in a radial direction by a deflector. In a preferred embodiment, the linear actuator is a hydraulic piston-cylinder assembly and the deflector is an inclined surface. Operation of the actuator in a first direction drives the bit into the inclined deflection surface, which causes the bit to pivot and protract radially outward of the tool housing to perforate the wall of a pipe. Operation of the actuator in the opposite direction pulls the bit back into the tool housing so that the perforator tool can be easily moved with a well casing.

1 . A tool ( 100 ) for perforating a pipe ( 52 ) from the interior of the pipe, said tool defining a longitudinal axis, the tool comprising:
 an actuator ( 130 ) operable to reciprocate a gudgeon ( 152 ); and   a bit ( 102 ) having a first end ( 156 ) pivotally coupled to said gudgeon and a second end ( 157 ) defining a claw;   whereby movement of said gudgeon in a first direction causes pivotal protraction of said claw outward from said axis.   
     
     
         2 . The tool of  claim 1  wherein:
 said first end of said bit defines a crosshead that is journaled to said gudgeon. 
 
     
     
         3 . The tool of  claim 1  further comprising:
 a deflector ( 162 ) disposed at a fixed distance from said actuator; 
 whereby linear movement of said gudgeon in said first direction is converted by said deflector to pivotal protraction of said claw radially outward from said axis. 
 
     
     
         4 . The tool of  claim 1  further comprising:
 a housing ( 104 ) enclosing said actuator and said gudgeon, said housing having an opening ( 166 ); 
 whereby translation of said gudgeon by said actuator in said first direction forcibly protracts said claw through said opening a distance beyond said housing, and translation of said gudgeon by said actuator in a second direction opposite to said first direction retracts said claw into said housing. 
 
     
     
         5 . The tool of  claim 1  further comprising:
 a generally cylindrical housing ( 104 ) enclosing said actuator and said gudgeon, said housing being centered about said axis and having top and bottom ends ( 140 ,  162 ), said bottom end ( 162 ) of said housing being inclined at an acute angle with respect to said axis; 
 whereby translation of said gudgeon by said actuator toward said bottom end of said housing causes said bit to contact and deflect off an inclined interior surface of said bottom end for pivoting said bit about said gudgeon. 
 
     
     
         6 . The tool of  claim 1  wherein:
 said actuator is a cylinder-piston assembly. 
 
     
     
         7 . The tool of  claim 1  wherein:
 said claw of said bit is generally planar having first and second parallel sides, a third convex side ( 158 ) and a fourth concave side ( 159 ). 
 
     
     
         8 . The tool of  claim 1  wherein:
 only a single bit is present. 
 
     
     
         9 . The tool of  claim 1  further comprising:
 a drawworks ( 12 ) carrying a tension member ( 28 ), 
 said housing ( 104 ) carried by said tension member; and 
 a vehicle ( 14 ) carrying said drawworks and providing power to said actuator. 
 
     
     
         10 . A method for perforating a pipe comprising the steps of:
 inserting a linear actuator ( 130 ) into said pipe ( 52 );   activating said actuator in a first direction to move a gudgeon ( 152 ) and a bit ( 102 ) attached to said actuator; and   pivoting said bit so that a distal pointed end ( 150 ) of said bit is protracted through the wall of said pipe.   
     
     
         11 . The method of  claim 10  further comprising the step of:
 activating said actuator in a second direction to retract said bit from said wall of said pipe. 
 
     
     
         12 . The method of  claim 10  further comprising the step of:
 pivoting said bit by a deflector ( 162 ). 
 
     
     
         13 . The method of  claim 12  wherein:
 said deflector is an inclined surface. 
 
     
     
         14 . The method of  claim 13  wherein:
 said bit has a convex edge ( 158 ); and 
 said inclined surface has a concave groove ( 168 ); 
 whereby a contact force of said convex edge against said concave groove acts to pivot said bit.