| 摘要 |
<p>A semi-submersible drill rig structure (2) includes a ring-like enclosure (4) surrounding a central drilling axis (D). In the structure are magazines (40,42) holding drill string elements (32,36) vertically. Lifting means (18) on the structure raise the vertical drill string elements from their magazines and carry them to the drilling axis. A guide ring (46) is displaceable to and from the drilling axis, in synchronism with the lifting means, to restrain the lower end of each raised element against pendulation. The magazines (40,42) are rotatable about vertical axes to bring the individual elements (32,36) under the line of movement of the lifting means (18) and guide ring (46). Well casing elements (78) are similarly restrained by the guide ring (46) as they also are carried in a vertical orientation to the drilling axis. The disposition of the magazines (40,42) in a structure (2) surrounding the drilling axis provides a relatively calm region through which the drilling operations can be conducted. </p> |
