| 摘要 |
<p>A running tool (20) comprising a stem 122) with a plug (40), a running nut (30), a wedge (32), a cam ring (34), and a bottom nut (36) together releasably connect and support a casing hanger (12), wear bushing (14) and packoff assembly (16) thereon. The bottom nut (36) supports the cam ring (34) and is wedged into engagement with the casing hanger (12) by downward axial movement of the running nut (30). A packoff assembly (16) is threaded on the casing hanger (12) and arranged so that rotation of the plug (40) and stem (22) rotates the wear bushing (14) and the packoff assembly (16) to set the packoff. The casing hanger (12), wear bushing (14) and packoff assembly (16) are lowered on the running tool (20) into final position within the wellhead. The running tool (20) is released by rotation of the stem (22) which raises the running nut (30), disengages the wedge (32) and allowing the cam ring (34) to disengage the casing hanger (12). A dead band between the wedge (32) and running nut (30) prevents accidental release of the running tool (30) form the casing hanger (12), and on further rotation, the running nut (30) becomes a driving element for threading the packoff assembly (16) so as to set the packoff. Important features of the invention include releasability of the running tool (20) before setting the packoff, if necessary, the aforementioned safety feature, and the capability of releasing the running nut (30) upon the application of low torque after the application of high torque thereto as a driving element.</p> |
