Multi-Piece Packing Element Containment System

Abstract

Methods and devices for retaining a packer element in a set condition within a wellbore and for preventing or minimizing extrusion of the packer element after setting. A packer device includes a plurality of deformable packer elements which radially surround a packer mandrel. One or more of the packer elements is contained against axial extrusion using a packer containment system. The packer containment system includes a flexible metal backup ring, which partially encases the packer element by substantially covering at least one axial side and a portion of the exterior radial surface of the packer element. The packer containment system also includes a plurality of annular support rings, or “petal rings” which have petal-shaped radial protuberances with slots between them.

1 . A containment assembly for a packer element in a packer device comprising:
 a backup ring which partially encases the packer element; and   a plurality of support rings adjacent the backup ring to prevent deformation of the backup ring.   
   
   
       2 . The containment assembly of  claim 1  wherein each of the support rings comprises an annular petal ring having a plurality of radially outwardly projecting petals that are separated by a plurality of slots. 
   
   
       3 . The containment assembly of  claim 2  wherein the support rings are radially offset from each other such that the petals of one of the plurality of rings covers the slots of an adjoining ring. 
   
   
       4 . The containment assembly of  claim 1  wherein: the backup ring comprises:
 a web portion that abuts an axial side surface of the packer element; and   a leg portion that overlies a radial outer surface of the packer element.   
   
   
       5 . The containment assembly of  claim 1  wherein each of the support rings presents a cross-sectional, substantially flat plate-form annular body that is disposed angularly outwardly with respect to the ring's axis. 
   
   
       6 . The containment assembly of  claim 5  wherein the body of the ring is disposed angularly outwardly with respect to the ring's axis at an angle that is from about 35° to about 45°. 
   
   
       7 . The containment assembly of  claim 6  wherein the angle is about 40°. 
   
   
       8 . The containment assembly of  claim 1  wherein there are three support rings. 
   
   
       9 . The containment assembly of  claim 1  wherein the backup ring is substantially comprised of a malleable metal. 
   
   
       10 . The containment assembly of  claim 5  wherein each of the support rings is deformed during a packer setting operation such that the angular outward disposition of the ring body becomes approximately 90°. 
   
   
       11 . The containment assembly of  claim 10  wherein the support rings do not contact an interior radial surface of a surrounding tubular member when in a set condition. 
   
   
       12 . A packer device for forming a fluid seal within a wellbore, comprising:
 a central packer mandrel;   a deformable packer element radially surrounding the mandrel, the packer element being axially compressible between an unset position wherein the element has a radially reduced condition, and a set position wherein the element has a radially expanded condition to form a fluid seal against a surrounding surface;   a setting sleeve that is moveable axially with respect to the mandrel for selectively axially compressing the packer element into its set position;   a packer element containment system to limit axial deformation of the packer element, the containment system comprising:   a) a backup ring which partially encases the packer element; and   b) a plurality of support rings adjacent the backup ring to prevent deformation of the backup ring.   
   
   
       13 . The packer device of  claim 12  wherein each of the support rings comprises an annular petal ring having a plurality of radially outwardly projecting petals that are separated by a plurality of slots. 
   
   
       14 . The packer device of  claim 13  wherein the support rings are radially offset from each other such that the petals of one of the plurality of rings covers the slots of an adjoining ring. 
   
   
       15 . The packer device of  claim 12  wherein each of the support rings presents a cross-sectional, substantially flat plate-form annular body that is disposed angularly outwardly with respect to the ring's axis. 
   
   
       16 . The packer device of  claim 15  wherein each of the support rings is deformed when the setting sleeve is moved axially to set the packer element, such that the angular outward disposition of the ring body becomes approximately 90°. 
   
   
       17 . The packer device of  claim 12  wherein there are three support rings. 
   
   
       18 . The packer device of  claim 12  wherein the backup ring is substantially comprised of a malleable metal. 
   
   
       19 . The packer device of  claim 12  wherein the support rings do not contact an interior radial surface of a surrounding tubular member when in a set condition. 
   
   
       20 . A method of containing a packer element against axial extrusion, the method comprising the steps of:
 a) assembling a packer device having:
 a central packer mandrel; 
 a deformable packer element radially surrounding the mandrel, the packer element being axially compressible between an unset position wherein the element has a radially reduced condition, and a set position wherein the element has a radially expanded condition to form a fluid seal against a surrounding surface; 
 a setting sleeve that is moveable axially with respect to the mandrel for selectively axially compressing the packer element into its set position; 
 a packer element containment system to limit axial deformation of the packer element, the containment system comprising a backup ring which partially encases the packer element; and a plurality of generally conically-shaped support rings adjacent the backup ring to prevent deformation of the backup ring; 
   b) moving the setting sleeve axially with respect to the packer mandrel to compress the packer element to its set position; and   c) axially flattening the support rings to form an axial structural barrier against extrusion of the packer element.