| 摘要 |
<p>The present invention relates to a marine riser system for use in offshore drilling operations. The system comprises two risers that are adapted to be vertically arranged with a substantially annular space therebetween, each riser consisting of a plurality of sections that are sealingly interconnected in end-to-end relationship. The outer riser comprises connecting means at the lower end thereof, said connecting means being adapted for connecting and sealing the lower end of the outer riser to a wellhead. The outer riser further comprises supporting means near the upper end thereof, said supporting means being adapted for being connected to a heave compensator system carried by a floating drilling means. Sealing means being arranged for sealing off the annular space at at least the lower end thereof, and closeable fluid pressure equalizing means are arranged in the wall of the outer riser, said means being adapted for equalizing the fluid pressures prevailine in the annular space and in the space outside the outer riser. The pressure equalizing means may comprise at least one closeable passage arranged near the upper end of the annular space, and at least one closeable passage arranged near the lower end of the annular space.</p> |
