By the OGJ Online Staff
LONDON, Mar. 8�A cross industry study led by France's Bouygues Offshore SA has made the case for the future viability of a fully floating liquefied natural gas chain.
Bouygues said the 18-month Azure R&D project, underwritten by the European Union's Thermie program, investigated designing floating liquefaction plants, floating LNG terminals, and offshore LNG transfer systems, and included "thorough testing" of all the key components of the chain.
The study concluded that "a fully floating LNG chain, from gas well to gas distribution network, is a safe and viable industrial proposal," said the company.
Bouygues headed a nine-company consortium made up M.W. Kellogg Ltd., Chantiers de l'Atlantique SA, Fincantieri SPA, FMC Europe, Gaz Transport & Technigaz SA, the Institut de Recherches de la Construction Navale, and classification societies Bureau V�tas SA, and Registro Italiano Navale.
Oil and gas companies RoyalDutch/Shell Group, TotalFinaElf SA, Chevron Corp., Texaco Inc., and Conoco Inc. gave "technical and financial support" to the project:
M W Kellogg developed two scenarios for the liquefaction barge, a stand-alone gas field in southeast Asia, involving a 3 million tonnes/year capacity, based on a dual mixed refrigerant process cycle; and a single processing train in West Africa, with a capacity of 1 million tonnes/year with a nitrogen expander cycle for the liquefaction of the associated gas for a deepwater oil field.
Fincantieri formulated a design for a floating receiving terminal located in southern Europe, while SN Technigaz's regasification process was designed around submerged combustion vaporizers with LNG storage capacity of 200,000 cu m.
Bouygues said the study found that the transfer of LNG in open seas "can be performed safely in a tandem loading configuration," using the boom-to-tanker designed by FMC. "A large scale model of this device was successfully tested, using motion data from basin tests," the company noted.
The Azure project looked at both steel and concrete hull designs for the LNG FPSO, with Chantiers de l'Atlantique developing the steel hull options, and Bouygues designing the concrete hull alternative.
Safety assessment of the various facilities linking the proposed floating LNG chain was conducted under the supervision of BV and RINA. The study found that by combining engineering practices from the offshore industry with those of onshore LNG terminals, the necessary safety criteria could be met, said Bouygues.
Advanced computer tools, developed by IRCN to address the liquid motion of the slack LNG storage tanks, found "sloshing" was not an issue, a fact confirmed by GTT via liquid motion tests and impact testing on membranes.