Patent ID: 7845402

Claim:
A sealing device for a radially expandable casing, the sealing device comprising: a first retainer ring; a second retainer ring; a gap disposed between the first retainer ring and the second retainer ring; and an extrudable sealing element disposed between the first retainer ring and the second retainer ring and in fluid communication with the gap, the extrudable sealing element being extrudable through the gap when the expandable casing is radially expanded, wherein the first retainer ring is disposed over a first portion of the extrudable sealing element and the second retainer ring is disposed over a second portion of the extrudable sealing element, wherein the first retainer ring is disposed above the second retainer ring and the first and second retainer rings each comprise upper and lower ends, the gap being disposed between the lower end of the first retainer ring and the upper end of the second retainer ring, and wherein the extrudable sealing element is disposed relative to the first and second retainer rings such that extrusion of the extrudable sealing element causes the extrudable sealing element to protrude outwardly through the gap, above the upper end of the first retainer ring, and below the lower end of the second retainer ring to engage a wall of a wellbore in at least three locations.