Patent ID: 8393388

Claim:
A high expansion retrievable plug for subterranean use, comprising: a mandrel supporting at least one sealing element set by compression to selectively seal against and release from a surrounding wall at a subterranean location; at least one extendable backup ring mounted to a support, said backup ring disposed between said sealing element and said support, whereupon compression of said sealing element said backup ring flexes to contact said wall and said sealing element; said support comprises a ramp on one side of said backup ring on which said backup ring slides and a ramped member on an opposite side of said backup ring from said ramp and initially axially spaced from said backup ring, whereupon axial compression of said sealing element said ramped member initially moves axially with respect to said sliding backup ring as said sliding backup ring slides on said ramp so that said ramped member then contacts said backup ring to retain said backup ring in contact with said wall and said sealing element.