Patent ID: 7552769

Claim:
A packoff nipple for sealing an annular space in a well pipe comprising: a tubular body, the tubular body adapted to be positioned within a bore of the well pipe, the annular space being formed between the tubular body and the well pipe; an uphole stop, having a concave stop surface, positioned around the tubular body, the uphole stop having a downwardly depending lip spaced radially and outwardly from the tubular body; a packer cup positioned around the tubular body and axially moveable therealong, the packer cup comprising an elastomeric mounting portion for positioning of the packer cup around the tubular body and an elastomeric skirt downwardly depending from the mounting portion and having an open bottom end; and a sealing assembly positioned around the tubular body and axially moveable therealong, the sealing assembly comprising one or more axially compressible elastomeric sealing rings, each sealing ring having a downhole face with a circumferential groove formed therein and an expansion portion adjacent the circumferential groove; wherein elevated fluid pressure in the annular space below the packer cup causes the skirt to seal the annular space and to further cause the packer cup to move slidably towards the seal assembly; and wherein movement of the packer cup towards the sealing assembly axially compresses the sealing assembly and causes at least the expansion portion of the sealing rings to expand radially to seal the annular space and the sealing assembly to move along the tubular body until a top portion of the sealing assembly adjacent the uphole stop contacts the uphole stop and the downwardly depending lip actuates the top portion into its actuated condition, for formfitting the top portion into the uphole stop, constraining the top portion within the uphole stop and away from the wellpipe, avoiding extrusion of the sealing assembly.