High pressure retrievable gravel packing apparatus

Claim 1

A retrievable well tool for use in maintaining sealing integrity between inner and outer concentric conduits under high temperature and pressure conditions in a subterranean well, the well tool comprising: an annular packing element at least partially plastically deformable at the well temperature and pressure, the packing element being initially radially expandable under axial compression; first and second relatively axially shiftable annular shoulders respectively disposed on opposite sides of said packing element, at least one of said shoulders being movable towards and away from the other shoulder; radially expandable, axially split backup rings between each shoulder and the packing element, the backup rings being radially expandable into abutment with the inner surface of the outer conduit upon movement of the first and second shoulders toward each other to compress the packing element, thereby opening an axial gap at the location of said axial split in each said backup rings; said axial split being defined by oppositely inclined surfaces facing said packing element; and a resiliently deformable barrier member disposed between each said backup ring and said packing element, said barrier members being resiliently deformable upon radial expansion and contraction of the backup rings, whereby said axial gaps in said backup rings adjacent the outer conduit are respectively sealed by expansion thereinto of portions of said barrier members; said oppositely inclined surfaces acting on said portions of said barrier elements to displace said portions from said axial gap and permit said backup rings to contract by movement of at least one of said annular shoulders away from the packing element, thereby permitting retrieval of the well tool.