| 摘要 |
<p>A transportable jack-up offshore well drilling rig has a relatively light openwork superstructure and three legs, and is transported to or from site in an upright position on a vessel which supports the rig at one end such that two of the legs extend down opposite sides of the vessel, while the third leg extends down in front of or behind the vessel. If the legs extend into the water during transport then the rig is typically arranged at the stern of the vessel but if the legs are clear of the water during the transport then the rig may be arranged at the bow of the vessel. The rig may be designed for tender assistance, in which case it carries only the drill works (derrick, draw works and rotary table) and a crane and all the other equipment (mud pumps, spare drill pipe, crew's quarters etc.) is carried on a floating tender moored to the rig, or it may be self-contained and require no permanent tender assistance. In either case, it may be converted to a well prod. platform after the drilling is completed. It is cheaper to construct than conventional rigs, towed to or from site, and is less likely to be damaged during installation or recovery.</p> |
