| 摘要 |
A riser structure for connecting from a floating structure to a subsea wellhead for drilling or production which has an upper flexible steel section and a lower flexible section connecting from the wellhead to the upper steel section, the lower section, cantilevered from the wellhead, having an increasing flexibility in the upward direction and having a greater flexibility near its upper connection than the upper section. The lower section is preferably of a more flexible material, such as titanium, with a thinner wall at its upper end than at the lower end.
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