| 摘要 |
A well system and method for completing petroleum oil and gas wells having special application to extreme environmental settings such as platform, sub sea, and floating vessel operations, and wells in frozen regions such as the Arctic, and the like. The invention is characterized by structure effectively defining a downhole wellhead including weight supporting apparatus in which the tubing hanger is supported and a pack-off with the casing for minimizing the effects of structural damage at the surface end of the well system. The system includes a tubing hanger releasably lockable in a casing at a downhole location and having sealing means for sealing the annulus within the casing around the hanger, a valve package lock releasably lockable in the tubing hanger, tubing strings connected with the valve package lock and extending upwardly therefrom, including tubing valves, a safety joint connected with the tubing strings above the valves, tubing strings connected with the safety joint extending upwardly to a tubing head at the wellhead, control fluid conduits connected from the tubing head through the safety joint to the valve package lock and tubing hanger for manipulation of the system during various phases of operation, and a composite handling string for running and pulling the well system including either of a slip joint or a hydraulic stop and orienting tool. The system permits a downhole wellhead to be functionally created below the mudline of offshore wells, Arctic wells, and the like.
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