Casing tensioning mechanism for a casing hanger

摘要

A mechanism mounts to a casing hanger for supporting the casing in tension. The mechanism includes a plurality of dogs mounted around the exterior of the casing hanger. Each of the dogs has wickers on its exterior which engage wickers formed in the bore of a wellhead housing. The dogs are carried within a recess. The recess has upper and lower parallel conical shoulders. A sleeve retains the dogs in a retracted position until tension has been applied. The sleeve releases the dogs by rotational movement of the running tool which runs the casing hanger.