| 摘要 |
<p>The present invention concerns a riser tube for use at great sea depths for drilling of wells in the seabed by means of a drill string, with the riser tube arranged to be connected between a wellhead at the seabed and a vessel, and arranged for use with a drilling fluid with sufficiently high density to balance the fluid pressure from the geological formations, with a sensor arranged to detect the level of the drilling fluid's level in the riser tube, and a return riser tube with an adjustable return riser pump. The new and inventive by the riser tube is that the return riser tube extends between the vessel and down to an outlet on the riser tube at a depth which is considerably below the sea surface, and at the same time at a height considerably above the seabed, and that the riser return pump is arranged by the outlet and arranged to adjust the drilling fluid level to a predetermined level by or above the outlet and considerably deeper than the sea surface, and that the drilling fluid has considerably higher density than what would be sufficient to balance the same fluid pressure from the geological formations by using a drilling fluid column entirely up to the surface, or to the vessel.</p> |
