High expansion plug with stacked cups

Abstract

A through tubing casing plug is disclosed. It features a stack of nested cup shaped elements that initially slope to reduce the run in diameter. The stack is compressed to force the periphery of the nested cups to move outwardly so that the collective outer surfaces of the cups can seal on the casing. The cups have sufficient initial thickness so that they remain intact despite some radial growth resulting from the compression process. In a particular example, the run in dimension is 2.13 inches and the stack expands to seal against casing with an inside diameter of 6.9 inches while holding a differential of 500 pounds per square inch and more.

We claim:  
     
         1 . A plug for downhole use, comprising: 
 a mandrel;    a sealing element mounted to said mandrel and movable between a run in and a set position, said set position defined by an outer diameter over 150% of the sealing element diameter in the run in position, said sealing element, in said run in position, comprising a stack of nested rings;    an anchor, which extends for downhole fixation of said mandrel with said sealing element in said set position as a result of relative movement with respect to said mandrel which movement also compresses said stack of nested rings.    
     
     
         2 . The plug of  claim 1 , wherein: 
 said stack of rings each having an outer periphery that is moved away from said mandrel by extension movement of said anchor.    
     
     
         3 . The plug of  claim 2 , wherein: 
 said rings each define an opening through which said mandrel extends and said outer periphery is rotated away from said mandrel in an arc centered in said opening    
     
     
         4 . The plug of  claim 2 , wherein: 
 the outer periphery of a plurality of said rings provides sealing capability in the wellbore in said set position.    
     
     
         5 . The plug of  claim 4 , wherein: 
 the outer periphery of all said rings provides sealing capability in the wellbore in said set position.    
     
     
         6 . The plug of  claim 1 , wherein: 
 the difference in outer diameter of said stack of nested rings is greater than 300% when comparing the run in to the set position.    
     
     
         7 . The plug of  claim 6 , wherein: 
 said sealing element withstands pressure differentials of at least 500 pounds per square inch in said set position.    
     
     
         8 . The plug of  claim 1 , wherein: 
 at least one of said stack of nested rings further comprises a seal for an opening in said ring that the mandrel passes through.    
     
     
         9 . The plug of  claim 1 , wherein: 
 all said rings in said stack of nested rings are oriented in the same direction    
     
     
         10 . The plug of  claim 1 , wherein: 
 at least one of said stack of nested rings is oriented in an opposite direction from another in said stack of nested rings.    
     
     
         11 . The plug of  claim 2 , wherein: 
 said outer peripheries of said nested rings define a cylindrical shape that grows uniformly until initial contact in the wellbore.    
     
     
         12 . The plug of  claim 1 , wherein: 
 adjacent nested rings contact each other on at least two discrete surfaces.    
     
     
         13 . The plug of  claim 12 , wherein: 
 a transition between said discrete surfaces is located adjacent said mandrel to define a cylindrical segment of each ring adjacent said mandrel and a tapered segment extending from said cylindrical segment.    
     
     
         14 . The plug of  claim 13 , wherein: 
 said tapered segments are flexed in unison to achieve said set position while said cylindrical segments are compressed together at the same time.    
     
     
         15 . The plug of  claim 5 , wherein: 
 the difference in outer diameter of said stack of nested rings is greater than 300% when comparing the run in to the set position.    
     
     
         16 . The plug of  claim 15 , wherein: 
 said sealing element withstands pressure differences of at least 500 pounds per square inch in said set position.    
     
     
         17 . The plug of  claim 16 , wherein: 
 said outer peripheries of said nested rings define a cylindrical shape that grows uniformly until initial contact in the wellbore.    
     
     
         18 . The plug of  claim 17 , wherein: 
 adjacent nested rings contact each other on at least two discrete surfaces.    
     
     
         19 . The plug of  claim 18 , wherein: 
 a transition between said discrete surfaces is located adjacent said mandrel to define a cylindrical segment of each ring adjacent said mandrel and a tapered segment extending from said cylindrical segment.    
     
     
         20 . The plug of  claim 18 , wherein: 
 said tapered segments are flexed in unison to achieve said set position while said cylindrical segments are compressed together at the same time.