Multi-layer Packer Backup Ring with Closed Extrusion Gaps
An extrusion ring has a base from which multiple segmented rows of rings integrally extend. Gaps in one row are offset from the adjacent row to cover any gaps. The rows gain strength from a common base that also presents relative rotation among the rows.
1 . A mandrel mounted backup ring assembly for extrusion protection for a mandrel mounted sealing element of a borehole barrier, comprising:
a ring comprising an axis, said ring mounted to the mandrel on at least one end of the sealing element and further comprising axially extending segments integrally extending from said ring at spaced locations from said mandrel, said segments integrally extending from said ring at a spaced radial locations to the mandrel, said base axially movably mounted to the mandrel for tandem axial movement with the sealing element to a set position of the borehole barrier, said segments extending from said ring at multiple diameters with respect to said mandrel with segments at each diameter forming a ring shape with gaps wherein gaps in adjacent said rings being circumferentially offset.
2 . The assembly of claim 1 , wherein:
said segments at different diameters have different lengths.
3 . The assembly of claim 1 , wherein:
said gaps are circumferentially offset as much as 12 degrees.
4 . The assembly of claim 1 , wherein:
said gaps are axially as long as said segments.
5 . The assembly of claim 1 , wherein:
said segments comprise free ends that bend when coming in contact with the borehole.
6 . The assembly of claim 1 , wherein:
said extending segments have a free end initially radially offset from an external surface of said ring and axially aligned with the axis of said ring.
7 . The assembly of claim 1 , wherein:
said multiple diameters comprise 2-4 diameters.
8 . The assembly of claim 1 , wherein:
said ring comprises an internal groove to retain a seal against the mandrel and the sealing element.
9 . The assembly of claim 1 , wherein:
said segments at different diameters have equal lengths.
10 . The assembly of claim 1 , wherein:
said gaps are axially shorter than said segments.