High pressure stripping heads and methods of making same

Abstract

A stripper element for use with stripping heads includes a one-piece, formed, generally cylindrical elastomer body having a top, a bottom, a central longitudinal through passage defining an inside surface, and an outer surface. The elastomer body includes an upper cylindrical portion and a lower truncated cone portion, the upper cylindrical portion including a cylindrical lip configured to seal against an inside surface of a stripper head. A one-piece, formed, flexible sheet insert (metal, fabric, or combination thereof) is positioned within at least a portion of either the upper cylindrical portion, the lower truncated cone portion, or both of the one-piece, formed, generally cylindrical elastomer body, the one-piece, formed, flexible sheet insert including a plurality of slots or through holes therein. Methods of making the stripper elements.

What is claimed is: 
     
         1 . A stripper element for use with stripping heads comprising:
 a) a one-piece, formed, generally cylindrical elastomer body ( 2 ) having a top ( 4 ), a bottom ( 6 ), a central longitudinal through passage ( 8 ) defining an inside surface ( 10 ), and an outer surface ( 12 ), the one-piece, formed, generally cylindrical elastomer body ( 2 ) comprising an upper cylindrical portion ( 14 ) and a lower truncated cone portion ( 16 ), the upper cylindrical portion ( 14 ) including a cylindrical lip ( 18 ) configured to seal against an inside surface ( 33 ) of a stripper head ( 32 ); and   b) a one-piece, formed, flexible sheet insert ( 22 ) (metal, fabric (Kevlar), or combination thereof) positioned within at least a portion of either the upper cylindrical portion ( 14 ), the lower truncated cone portion ( 16 ), or both of the one-piece, formed, generally cylindrical elastomer body ( 2 ), the one-piece, formed, flexible sheet insert ( 22 ) including a plurality of slots ( 24 ) or through holes ( 26 ) therein.   
     
     
         2 . The stripper element of  claim 1 , wherein the one-piece, formed, generally cylindrical elastomer body comprises one or more natural elastomers, one or more synthetic elastomers, or combinations and mixtures thereof. 
     
     
         3 . The stripper element of  claim 2 , wherein the one-piece, formed, generally cylindrical elastomer body comprises natural rubber (NR). 
     
     
         4 . The stripper element of  claim 2 , wherein the one-piece, formed, generally cylindrical elastomer body comprises a synthetic rubber selected from styrene-butadiene rubber (SBR), butyl rubber (IIR), nitrile rubber (otherwise known as NBR rubber and Buna-N), hydrogenated nitrile (HNBR), neoprene (CR), ethylene propylene diene monomer (EPDM) rubber, fluoroelastomers, polyurethanes (AU), and combinations, mixtures, and layered versions thereof. 
     
     
         5 . The stripper element of  claim 1 , wherein the one-piece, formed, flexible sheet insert comprises a sheet of metal, fabric, or layered combination thereof. 
     
     
         6 . The stripper element of  claim 1 , wherein the one-piece, formed, flexible sheet insert is molded into or otherwise surrounded by the elastomer forming the body of the stripper element. 
     
     
         7 . The stripper element of  claim 1 , wherein the one-piece, formed, flexible sheet insert is expanded metal sheet. 
     
     
         8 . The stripper element of  claim 1 , wherein the one-piece, formed, flexible sheet insert is stainless steel sheet. In certain embodiments the stainless steel may be type 304. Certain embodiments may have a minimum tensile strength of 515 MPa, a minimum yield strength at 0.2% of 205 MPa, a minimum elongation (% in 50 mm) of 40, a maximum Rockwell B hardness of 92, and a maximum Brinell hardness of 201, all in accordance with ASTM A240/A240M. 
     
     
         9 . The stripper element of  claim 1 , wherein the plurality of slots or through holes in the one-piece, formed, flexible sheet insert are a plurality of round through passages therethrough. 
     
     
         10 . A stripping assembly comprising a stripper head insert ( 30 ) and the stripper element of  claim 1  inserted into a stripper head body ( 32 ), the stripping assembly further comprising a hinged clamp ( 34 ) configured to clamp the stripper head insert ( 30 ) and stripper element body ( 2 ) into the stripper head body ( 32 ), whereby the mating cylindrical lip ( 36 ) fits into a main clamp groove ( 35 ), and a swing bolt ( 38 ) fits into a clamp groove ( 40 ). 
     
     
         11 . The stripping assembly of  claim 10  wherein the stripper head body ( 32 ) is configured to connect to a drillpipe or other tubular or tool through a chevron seal ( 60 ). 
     
     
         12 . The stripping assembly of  claim 10  wherein the stripper head ( 32 ) further comprises an NPT outlet ( 70 ). 
     
     
         13 . The stripping assembly of  claim 11  wherein the stripper head body connections comprise Hydril PH6 connections, having an external seal/torque shoulder, an intermediate torque shoulder, and an internal seal. 
     
     
         14 . The stripping assembly of  claim 10  wherein the central longitudinal through passage of the one-piece, formed, generally cylindrical elastomer body has an initial diameter that is from about 0.56 to about 0.59 times an external diameter of a tubing selected from 2⅜ inch, 2⅝ inch, 2⅞ inch, and 3½ inch. 
     
     
         15 . The stripping assembly of  claim 11  wherein the stripper head body further comprises a combination of metallurgy and structural reinforcement such as to prevent failure of the stripping head upon exposure to inner pressure up to 1,000 psia, or up to 1,500 psia, or up to 2,000 psia, or up to 2,500 psia, or up to 3,000 psia, or up to 4,000 psi or higher, such as may be experienced during frac plug drilling operations. 
     
     
         16 . A method of making a stripper element, comprising:
 a) providing a mold for forming a one-piece, formed, generally cylindrical elastomer body ( 2 ) having a top ( 4 ), a bottom ( 6 ), a central longitudinal through passage ( 8 ) defining an inside surface ( 10 ), and an outer surface ( 12 ), the one-piece, formed, generally cylindrical elastomer body ( 2 ) comprising an upper cylindrical portion ( 14 ) and a lower truncated cone portion ( 16 ), the upper cylindrical portion ( 14 ) including a cylindrical lip ( 18 ) configured to seal against an inside surface ( 33 ) of a stripper head body ( 32 );   b) selecting an elastomer;   c) selecting a one-piece, formed, flexible insert ( 22 ) including a plurality of slots ( 24 ) or a plurality of through holes ( 26 ) therein;   d) positioning the one-piece, formed, flexible insert ( 22 ) within the mold;   e) filling the mold with an elastomer so that that the one-piece, formed, flexible insert ( 22 ) is surrounded by the elastomer;   f) heating the mold and the elastomer to temperature sufficient to cause the elastomer to flow and form the one-piece, formed, generally cylindrical elastomer body ( 2 ); and   g) cooling the mold and the elastomer.   
     
     
         17 . The method of  claim 16  comprising selecting the plurality of through holes from hole shapes selected from circular and non-circular, and selecting the plurality of slots from slot shapes selected from rounded ends and non-rounded ends. 
     
     
         18 . The method of  claim 16  comprising selecting the elastomer from one or more natural elastomers, one or more synthetic elastomers, or combinations and mixtures thereof. 
     
     
         19 . The method of  claim 18  comprising selecting the elastomer from styrene-butadiene rubber (SBR), butyl rubber (IIR), nitrile rubber (otherwise known as NBR rubber and Buna-N), hydrogenated nitrile (HNBR), neoprene (CR), ethylene propylene diene monomer (EPDM) rubber, fluoroelastomers, polyurethanes (AU), and combinations, mixtures, and layered versions thereof. 
     
     
         20 . A method of making a stripper element, comprising:
 a) providing a mold for forming a one-piece, formed, generally cylindrical elastomer body ( 2 ) having a top ( 4 ), a bottom ( 6 ), a central longitudinal through passage ( 8 ) defining an inside surface ( 10 ), and an outer surface ( 12 ), the one-piece, formed, generally cylindrical elastomer body ( 2 ) comprising an upper cylindrical portion ( 14 ) and a lower truncated cone portion ( 16 ), the upper cylindrical portion ( 14 ) including a cylindrical lip ( 18 ) configured to seal against an inside surface ( 33 ) of a stripper head body ( 32 );   b) selecting an elastomer;   c) selecting a one-piece, formed, flexible insert ( 22 ) as described herein formed into a cylindrical metal ring;   d) welding or brazing an edge of the cylindrical ring to a stripper head insert formed as a steel disk;   e) positioning the cylindrical metal ring within the mold;   f) filling the mold with an elastomer so that the one-piece, formed, flexible insert ( 22 ) is surrounded by the elastomer;   g) heating the mold and the elastomer to temperature sufficient to cause the elastomer to flow and form the one-piece, formed, generally cylindrical elastomer body ( 2 ); and   h) cooling the mold and the elastomer.