For the third time in just over three years, theDeepwater Nautilus team has set a water-depth record for a moored offshore drilling rig while working for Shell.
The new record is 8,717 ft of water in Alaminos Canyon block 857 of the Gulf of Mexico, set by theDeepwater Nautilus, Shell, and Delmar anchor-handling company on Sept. 25. The two previous world records -- both by the Deepwater Nautilusin the GoM -- were 8,009 ft of water in March 2002 at Alaminos Canyon block 857 and 7,790 ft water depth in June 2001 on Alaminos Canyon block 557.
Constructed in 2000 to work in water depths of 5,000 feet with self-contained mooring, theDeepwater Nautilushas since used a preset mooring system to achieve the records in greater than 8,000 ft of water.
The preset mooring system uses eight suction piles with polyester mooring lines, which are deployed by an anchor-handling vessel ahead of the rig's arrival at a location. The lines are connected to each of the rig's mooring wires to form a taut mooring system.
At Alaminos Canyon block 857, theDeepwater Nautilus moored the first four legs of the preset mooring system in 24 hours. Crews were then able to start jetting in the 36-in. casing, and the rest of the mooring system was run offline. Compared with traditional catenary mooring systems, the preset system reduces mooring pattern size while achieving higher holding power with less rig-mooring time and excellent positioning around pipelines and seafloor obstructions.