Multi-component Anti-extrusion Barrier for a Compression Set Subterranean Barrier

Abstract

A backup ring assembly is disposed between opposed cones. The assembly rides up a wedge ring to contact a surrounding tubular when the opposed cones are pressed axially together to also compress the sealing element. The backup ring assembly has nested split rings that are slant cut for the split. The split for the nested rings can be circumferentially aligned or offset. Another ring is stacked axially adjacent the nested rings and has a slant cut for a split that is preferably rotated from the slant cuts of the nested rings. The interface of the nested rings can be along a line that is parallel to the mandrel axis or askew to the mandrel axis. The preferred material is a non-metallic composite material.

I claim: 
     
         1 . An extrusion barrier assembly for a compression set sealing element that selectively isolates one subterranean location from another, comprising:
 a sealing element mounted on a mandrel;   an axially movable compressing assembly for said sealing element mounted on said mandrel;   said extrusion barrier comprising at least one row of radially nested rings mounted over said mandrel, said rings extending in a radial direction from said mandrel to an end between straight sides and at least a portion of said rings are driven away from said mandrel by said compressing assembly.   
     
     
         2 . The assembly of  claim 1 , wherein:
 said rings are split to define adjacent ends.   
     
     
         3 . The assembly of  claim 1 , wherein:
 said split is in a plane that is skewed to an axis of said mandrel.   
     
     
         4 . The assembly of  claim 2 , wherein:
 said splits are circumferentially aligned.   
     
     
         5 . The assembly of  claim 2 , wherein:
 said splits are circumferentially offset.   
     
     
         6 . The assembly of  claim 2 , wherein:
 said ends overlap each other after said compressing assembly drives said nested rings.   
     
     
         7 . The assembly of  claim 1 , wherein:
 said rings are made of a non-metallic material.   
     
     
         8 . The assembly of  claim 7 , wherein:
 said rings are made of a composite material.   
     
     
         9 . The assembly of  claim 2 , further comprising:
 an additional row with at least one additional ring adjacent said nested rings.   
     
     
         10 . The assembly of  claim 9 , wherein:
 said additional ring is split to define adjacent ends.   
     
     
         11 . The assembly of  claim 10 , wherein:
 said split in said additional ring is circumferentially offset from said split in said nested rings.   
     
     
         12 . The assembly of  claim 11 , wherein:
 said ends of said additional ring overlap each other after said compressing assembly drives said nested rings.   
     
     
         13 . The assembly of  claim 12 , wherein:
 said additional ring is made of a non-metallic material.   
     
     
         14 . The assembly of  claim 13 , wherein:
 said additional ring is made of a composite material.   
     
     
         15 . The assembly of  claim 2 , further comprising:
 at least one wedge ring between said sealing element and said extrusion barrier that presents a ramp for said extrusion barrier as said extrusion barrier is moved away from said mandrel by said compressing assembly.   
     
     
         16 . The assembly of  claim 15 , wherein:
 said split is in a plane that is skewed to an axis of said mandrel.   
     
     
         17 . The assembly of  claim 16 , wherein:
 said ends overlap each other after said compressing assembly drives said nested rings.   
     
     
         18 . The assembly of  claim 17 , wherein:
 said rings are made of a non-metallic material.   
     
     
         19 . The assembly of  claim 18 , further comprising:
 an additional row with at least one additional ring adjacent said nested rings. said additional ring is split to define adjacent ends;   said ends of said additional ring overlap each other after said compressing assembly drives said nested rings.   
     
     
         20 . The assembly of  claim 19 , wherein:
 said split in said additional ring is circumferentially offset from said split in said nested rings.   said additional ring is made of a non-metallic material.