Slip Element and Assembly for Oilfield Tubular Plug

Abstract

A slip assembly for anchoring a sealing device, such as a bridge plug, frac plug, or packer, in an oilfield tubular. The slip assembly includes a polymeric slip cone and slip stop disposed along a mandrel. Plural wedge shaped slip elements, which each have plural teeth for selectively engaging the interior circumference of the tubular, are pressure molded of powered iron that is sintered. The plural slip elements are spaced apart from each other such that the sum length of the spaces between them along the interior circumference of the tubular accounts for greater than thirty percent of the circumference. The teeth of the plural slip elements are driven against the interior circumference of the tubular when the slip cone and the slip stop are driven toward one another along the mandrel by a setting tool.

What is claimed is: 
     
         1 . A slip assembly for anchoring a sealing device that is assembled about a mandrel and set in place in a tubular with a setting tool, the tubular having an interior circumference, the slip assembly comprising:
 a slip cone fabricated from a polymeric material and disposed along said mandrel;   a slip stop fabricated from a polymeric material and disposed along said mandrel;   plural slip elements, each configured in a wedged shape, and having plural teeth disposed upon an arcuate surface thereof for selectively engaging the interior circumference of the tubular, and wherein said plural slip elements are pressure molded of powered iron that is sintered, and wherein   said plural slip elements are disposed between said slip cone and said slip stop, and spaced apart from each other, and wherein   said teeth of said plural slip elements are driven against the interior circumference of the tubular when said slip cone and said slip stop are driven toward one another along said mandrel by the setting tool, and wherein   the sum length of the spaces between said plural slip elements along the interior circumference of the tubular accounts for greater than thirty percent of the interior circumference length of the tubular.   
     
     
         2 . The slip assembly of  claim 1 , and wherein:
 said powered iron further contains carbon, and wherein   said arcuate surface of said plural slip elements is surface hardened.   
     
     
         3 . The slip assembly of  claim 2 , and wherein:
 said plural slip elements are molded from powdered iron comprising carbon in the range of 0.6 to 0.9 percent by weight, and also comprising powered copper in the range from 1.5 to 3.9 percent by weight, and wherein   said pressure molded plural slip elements are heat sintered to a temperature above the melting point of copper.   
     
     
         4 . The slip assembly of  claim 2 , and wherein:
 said arcuate surface of said plural slip elements are surface hardened by oxy-gas flame and rapidly cooled to yield a case surface having a Rockwell C-scale hardness value greater than fifty-five.   
     
     
         5 . The slip assembly of  claim 1 , and wherein:
 said sum length of the spaces between said plural slip elements along the interior circumference of the tubular accounts for greater than fifty percent of the interior circumference length of the tubular.   
     
     
         6 . The slip assembly of  claim 1 , further comprising:
 plural pins disposed between said plural slip elements and said slip cone to rigidly fix said plural slip elements to said slip cone, and wherein   said plural pins have a shear strength selected to shear under force of the setting tool.   
     
     
         7 . The slip assembly of  claim 1 , further comprising:
 plural pins disposed between said plural slip elements and said slip stop to rigidly fix said plural slip elements to said slip stop, and wherein   said plural pins have a shear strength selected to shear under force of the setting tool.   
     
     
         8 . The slip assembly of  claim 1 , further comprising:
 plural pins disposed between said plural slip elements and said slip stop and said slip cone to rigidly fix said plural slip elements to said slip stop and said slip cone, and wherein   said plural pins have a shear strength selected to shear under force of the setting tool.   
     
     
         9 . The slip assembly of  claim 8 , and wherein:
 said plural pins are fabricated from fiber reinforced polymeric material.   
     
     
         10 . The slip assembly of  claim 1 , and wherein:
 said slip cone and slip stop polymeric materials are fiber reinforced, and wherein   the mandrel is fabricated from a fiber reinforced polymeric material.   
     
     
         11 . A slip assembly for anchoring a sealing device that is assembled about a fiber reinforced polymeric mandrel and set in place in a tubular with a setting tool, the tubular having an interior circumference, the slip assembly comprising:
 a slip cone fabricated from a fiber reinforced polymeric material and disposed along the mandrel;   a slip stop fabricated from a fiber reinforced polymeric material and disposed along the mandrel;   plural slip elements, each configured in a wedged shape, and having plural teeth disposed upon an arcuate surface thereof for selectively engaging the interior circumference of the tubular, and wherein said plural slip elements are pressure molded from powdered iron comprising carbon in the range of 0.6 to 0.9 percent by weight, and also comprising powered copper in the range from 1.5 to 3.9 percent by weight, and wherein   said pressure molded plural slip elements are heat sintered to a temperature above the melting point of copper, and wherein   said arcuate surface of said plural slip elements are surface hardened by oxy-gas flame and rapidly cooled to yield a case surface having a Rockwell C-scale hardness value greater than fifty-five;   plural pins, fabricated from a fiber reinforce polymeric material, disposed between said plural slip elements and said slip stop and said slip cone to rigidly fix said plural slip elements between said slip stop and said slip cone, and wherein   said plural pins have a shear strength selected to shear under force of the setting tool, and wherein   said plural slip elements are spaced apart from each other such that the sum length of the spaces between said plural slip elements along the interior circumference of the tubular accounts for greater than thirty percent of the interior circumference length of the tubular, and wherein   said teeth of said plural slip elements are driven against the interior circumference of the tubular when said slip cone and said slip stop are driven toward one another along said mandrel by the setting tool.