ABS to class first cell spar for Kerr McGeeNews // March 14, 2003
The project marks ABS' fifth classification contract from Kerr-McGee Oil & Gas for a spar offshore facility. The project will draw on ABS' experience with spar technology and industry expertise for deepwater developments, says Luiz Feijo, ABS project manager.
"ABS offers Kerr-McGee the expertise to face the technical challenges of the Red Hawk frontier project while meeting the schedule requirements," said Feijo.
The entire project, adds Feijo, is expected to complete within two years of project sanction, with first-gas scheduled for second quarter 2004.
"Engineering and fabrication are proceeding in parallel. For ABS, this means we are working very diligently to review and approve designs in an efficient manner, without risk of delay," said Feijo.
He added that ABS' experience in working with Kerr-McGee and its deepwater pursuits will help facilitate its participation in the effort.
To date, ABS has supported Kerr-McGee with classification services for the caisson or classic first-generation spar and for the truss spar, a second-generation design using less steel while allowing additional deck load. ABS has classed the following Kerr-McGee spars, all installed in the Gulf of Mexico: the Neptune spar - a classic design; and the Nansen, Boomvang and Gunnison truss spars.
"The cell spar - a third-generation design - provides the industry with continued opportunities to lower fabrication costs, again reducing the complexity of steel fabrication by simplifying the design concept, thus increasing operator flexibility in selecting where the hull can be built. The first and second generation designs, explains Feijo, required specialized shipyard fabrication, and all have been constructed in European and Far East yards and have required transport to Gulf of Mexico waters.
The Red Hawk cell spar is planned for Garden Banks Block 877 in 5,300 feet of water, representing continued deepwater advancement for spar technology, says Don Vardeman, Kerr-McGee's director of worldwide deepwater facilities. Kerr-McGee is the operatorfor Red Hawk with a 50 per cent interest. Ocean Energy Inc holds the remaining 50 per cent.
The cell spar's new hull concept features six outer cylinders or cells surrounding an inner cell, all connected by framing decks at regular intervals, rather than a single large caisson unit; a polyester mooring system, which is more buoyant than traditional chain-wire systems; and a topside-operated compressed air ballast system. "ABS has given its 'approval in principle' of the hull design and is providing advice on engineering and inspection issues," said Feijo.
The cell spar hull will have a diameter of 64 feet, with each of the seven cylinders or tubes two feet apart and measuring 20 feet in diameter. The hull length is 560 feet and includes four heave plates to facilitate stability. Strakes or spiral vanesall along the tubes help to reduce vortex-induced vibration.
ABS also is providing insight into development of the mooring system design, says Feijo, explaining that ABS issued its Guidance Notes on Synthetic Moorings in 1999. Kerr-McGee's Red Hawk is one of the first Gulf of Mexico installations to utilize the technology.
The industry has traditionally used wire and rope chain for its mooring systems, advises Feijo. The polyester material, however, offers the industry several advantages, such as reduced mooring system weight and improved payload options.
"The use of light-weight synthetic rope allows a floating production facility to support more revenue-producing equipment. The availability of synthetic materials and innovative mooring systems, such as the one being developed for Red Hawk, is extendingthe economic capability of existing floating technology into deeper waters," said Feijo.
ABS will class the Red Hawk spar as an +A1 Floating Offshore Installation (FOI) and the platform will maintain a U.S. Coast Guard Certificate of Inspection (COI), which ABS will facilitate on behalf of the USCG. The production facilities are not included in the classification.
ABS' scope of work includes: classification of the unit, addressing the hull structure, stability, global performance, mooring, safety, marine and utility systems and other issues related with the safety of the vessel and crew at sea; work on behalf ofthe USCG; and work as the Certified Verification Agent (CVA) on behalf of the U.S. Minerals Management Service.
Technip-Coflexip is designing and fabricating both the hull and topsides, with fabrication taking place at Gulf Marine Fabricators in Ingleside and Aransas Pass, Texas.
Initial gas throughput capacity is set at 120 million standard cubic feet per day, with a potential increase to 300 million standard cubic feet per day.