BP plc plans to “retrieve and rebuild” all of the seabed production equipment from the Thunder Horse field in the deepwater Gulf of Mexico (GOM), a significant setback which could push the ramp-up to mid-2008 — as much as three years longer than originally anticipated.

The new delay followed a series of tests conducted by the London-based major in the past four months that revealed metallurgical failure in components of the subsea system.

The largest semisubmersible platform in the world is expected to have capacity for up to 250,000 bbl/d of oil and 200 MMcf/d of gas when it begins operations. However, the platform, which is drilling 6,000 feet into the Mississippi Canyon of the GOM, already has announced several production delays. The platform, in which ExxonMobil Corp. owns a 25% stake, eventually will transport oil and gas to existing shelf and onshore interconnections via the Mardi Gras transportation system.

Last year following Hurricane Dennis, the platform was found listing 20 degrees, and BP said then it was unlikely commercial production would begin before the end of 2005 (see NGI, Aug. 1, 2005). Following hurricanes Katrina and Rita, ramp-up was again revised, and BP said production would begin by mid-2006 (see NGI, Dec. 5, 2005). Last month, Wood Mackenzie reported the ramp-up had been delayed into 2007 (see NGI, Aug. 21).

The latest problems, said BP, “became evident when it conducted precommissioning tests by pumping water through the system to establish system integrity. The equipment passed all the normal industry standard tests and regulatory requirements. But when the company carried out more prolonged and rigorous testing, as an additional safety precaution, a failure occurred on a subsea weld.”

Following the test failure, BP decided to retrieve both the damaged seabed manifold and a second manifold for further examination and onshore testing. The second manifold displayed a similar failure during testing earlier this month, BP said.

“In view of these failures, BP today said it would now retrieve and replace all the subsea components it believes could be at risk. This work will be done over the course of the next year and the company said it does not expect production from Thunder Horse to begin before the middle of 2008.”

Thunder Horse was discovered in 1999, and the platform is designed to use the largest production drilling quarters semisubmersible platform in the world. Besides Thunder Horse, BP now produces about 270,000 boe/d from nearly two dozen GOM fields, including BP-operated facilities at Pompano, Marlin, Horn Mountain and Na Kika.

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