| 摘要 |
A floating drilling and production unit comprising two independently floating bodies: (1) an outer, larger, substantially cylindrical buoyant caisson 2 with an enlarged skirt 6 around its lower perimeter to dampen sea-induced motions and (2) a constant tension wellhead buoy 4 captured within the central well of the outer caisson. The outer caisson supports the weight of the drilling platform, machinery, storage and living quarters and is ballasted and anchored in a manner similar to a conventional semisubmersible vessel. The buoy 4 supports the wellheads of completed wells and is held in a constant position relative to the ocean floor by the production risers and/or tendons. The buoy has a tapered shape that minimizes contact and interaction between the wellhead buoy and the caisson. Thus, the wellhead buoy is substantially unaffected by sea-induced motions of the buoyant caisson. Drilling operations with equipment supported by the caisson are carried out through a moonpool 5 extending vertically through the wellhead buoy. <IMAGE> |
