MULTI-POINT HIGH PRESSURE SEAL FOR EXPANDABLE TUBULAR CONNECTIONS

摘要

An expandable threaded connection between segments of expandable tubulars provides multiple sealing points along the pin and box members (10, 20) that can withstand high pressure. A gap (a) is utilized that is created between the pin nose (31) and the back (32) of the box member (20) when the threaded connection is made up and a reverse trapping angle (theta) machined into the pin nose end (32) and the back (32) of the box (20). The radial expansion of the tubulars causes axial movement of the pin nose (31) and the box member (20) until the pin nose (31) is in contact with the back (32) of the box member (20), thereby closing the gap (a) and forcing the pin nose (31) into sealing engagement with the back (32) of the box member (20). The reverse trapping angle (theta) forces the nose (31) of the pin member (10) outwardly (i.e., toward the outer diameter of the expandable tubular string) as it is forced into contact with the back (32) of the box member (20) during the expansion process. The force imparted on the pin nose (31) by the reverse trapping angle (theta) creates a high pressure radial seal between surfaces of the pin member (10) and the box member (20). The contact point between the nose (31) of the pin member (10) and the back (32) of the box member (20) creates a high pressure axial seal. By controlling the initial gap size (a) and the reverse trapping angle (theta), it can be ensured that the axial and radial sealing points are strengthened by the expansion process. The combination of the radial and axial seals created by the expansion process provides an expanded threaded connection that is capable of withstanding high pressure.