Southern France is emerging as one of Europe's premier test centers for motion analysis of FPSOs. The BGO First wave tank at the Oceanide indoor basin at La Seyne sur Mer has been used recently for studies of the Girassol riser towers and the Moho Bilondo floater, and for Bouygues Offshore's so far untried multifunction barge and wellhead barge concepts.
Model test of a mooring system for a new FPSO at the Oceanide wave tank.
Oceanide is a private company that has operated and rented its basin (built with local public funding) since 1998. The company is also a specialist in coastal engineering, with facilities including a wave tank and a 2D tunnel. It designed and tested the Condamine harbor extension in Monaco where a 400-m floating concrete barge acts as a wave-breaker.
According to Oceanide Assistant Director Guy Facon, its basin can perform a wider range of tests than most others, due largely to its areal extent, which has allowed curves and "breaks" to be built in, reminiscent of a race-track. All types of sea states can be simulated, with both regular and irregular waves. Due to its two large under-basin tubes and associated "tranquilization" chambers, current impact can also be modeled more accurately, with small levels of turbulence. Also, irregular wind generation can be provided with a controlled amount of turbulence, a facility offered by few other basins.
Another of its special features is Trajecto, a submarine trajectory system developed by Oceanide to measure movement under water of export and mooring lines. It allows one or more targets to be monitored in real time, through instantaneous recording of X, Y, and Z coordinates.
Motion results of Trajecto have been verified by the Krypton Rodym DMM system, which can perform areal measurement of the model motions within 6° of freedom. This contact-less tracking system employs infra-red cameras aimed at three infra-red active markers on the model.
For TotalFinaElf's Moho-Bilondo development offshore Congo, Ocean-ide built a model of the proposed floating production unit, followed by validation tests. It did a similar exercise for the same operator's current development off Libya, in this case performing tests of the FPSO and its chain- moored turret.