초록 ▼

A floating drilling and production unit comprising two independently floating bodies: (1) an outer, larger, substantially cylindrical buoyant caisson with an enlarged skirt around its lower perimeter to dampen sea-induced motions and (2) a wellhead buoy captured within the central well of the outer

A floating drilling and production unit comprising two independently floating bodies: (1) an outer, larger, substantially cylindrical buoyant caisson with an enlarged skirt around its lower perimeter to dampen sea-induced motions and (2) a wellhead buoy 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 constant tension buoy supports the wellheads of completed wells and is held in a constant position relative to the ocean floor much like a tension leg platform by the production risers of completed wells, tendons, or a combination of tendons and risers. Production risers are kept taut by the buoyancy of the constant tension buoy. The constant tension 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 bouyant caisson. Drilling operations with equipment supported by the caisson are carried out through a moonpool extending vertically through the wellhead buoy.

대표청구항 ▼

A semi-submersible vessel, comprising: a first and a second independently floating bodies, the first body being a constant tension buoy having a central well extending vertically through a hull of the buoy and allowing conducting of a well drilling operation, said buoy further comprising a plurality

A semi-submersible vessel, comprising: a first and a second independently floating bodies, the first body being a constant tension buoy having a central well extending vertically through a hull of the buoy and allowing conducting of a well drilling operation, said buoy further comprising a plurality of radially located bays, each well bay being adapted to receive a rise line therein, the second body being a buoyant caisson having a central well extending through a hull of the caisson and wherein the first body is captured inside the central well of the second body and is held under a constant tension through a constant distance connection of the first body to a floor of a body of water independently from said second body and wherein said constant tension buoy is substantially unaffected by wave conditions affecting the buoyant caisson during operation, and wherein effects of wave conditions acting on both bodies are substantially reduced on the constant tension buoy.