Wicker-type face seal and wellhead system incorporating same

摘要

A wellhead seal assembly that forms a metal-to-metal seal between inner and outer wellhead members and a face seal between inner wellhead members. The face seal is created by two opposing sealing surfaces on inner wellhead members that sealingly engage each other. The inner wellhead members that interact to form a face seal may be a casing hanger, bridging hanger, or lockdown hanger. A wicker profile formed on one of the opposing seal surfaces bites into the opposing seal surface in response to a load. The face seal is designed such that well pressure enhances the face seal.

主权项

1. A wellhead assembly with an axis, comprising:
an outer wellhead member having a bore; a casing hanger located in the bore with a rim on an upper end having an upward facing seal surface, the casing hanger having an interior profile and a lower end for securing to a string of casing; a casing hanger packoff that seals between an outer diameter portion of the casing hanger and the bore of the outer wellhead member; an upper hanger located in the bore and having a downward facing shoulder that lands on the rim and has a downward facing seal surface that seals against the upward facing seal surface, the upper hanger having an interior profile in fluid communication with the interior profile of the casing hanger and a lower end free of attachment to any string of casing; a wicker profile formed on one of the seal surfaces, the wicker profile comprising concentric grooves with crests that are embedded into the other seal surface when the upper hanger is set into place; and an annular member encircling an outer wall of the upper hanger and wedged between the upper hanger and the bore of the outer wellhead member, the annular member resisting any upward movement of the upper hanger relative to the casing hanger after the upper hanger is set.