BP PLC said the Thunder Horse semisubmersible platform on Mississippi Canyon Block 778 in the deepwater Gulf of Mexico, 150 miles southeast of New Orleans, was discovered listing 20-30° after Hurricane Dennis passed through the area.
The cause of the platform’s imbalance has not been determined, and BP continues to assess the extent of the damage. Thunder Horse oil field is in development and has not yet begun production. A vessel in the area discovered the platform’s condition at 8:30 a.m. July 11.
BP continues to work with the US Coast Guard to create a response plan. At presstime last week, crews had boarded the listing platform, restored partial power, and began pumping operations to restore the platform to normal, said BP. Boarding crews also retrieved the platform’s data recorders, expected to help determine the cause of the platform’s tilt. Workers boarded the platform after safety evaluations by BP and the USCG.
An underwater inspection by remotely operated vehicles showed no evidence of damage to the hull, BP said. BP hired four contract response vessels, and the USCG provided the Cutter Pelican and a Dauphin helicopter.
The Thunder Horse platform was evacuated on July 8 in anticipation of Hurricane Dennis. There has been no known release of any fuel or hazardous substances, BP said.
The company immediately notified the US Minerals Management Service and the USCG. BP and the USCG are collaborating to establish a unified command base in Morgan City, La.
Platform details
The platform is moored in 6,050 ft of water. BP holds a 75% interest and operates the development. Its partner, ExxonMobil Corp., holds 25%. BP expects first oil in the second half.
A section of the unit BP calls production drilling quarters is designed to process 250,000 b/d of oil, 200 MMcfd of gas, and 140,000 b/d of produced water. The platform also is equipped for the injection of 200,000-300,000 b/d of water into the reservoir. The main deck dimensions are 367 ft by 446 ft.
The topsides has three production-utilities modules with a maximum 21,000-ton lift weight. The platform can generate 90 Mw of power from its main generations. Its derrick has a 2-million-lb rating and provides auxiliary hoisting capability.
The hull has a dry transport weight of 59,500 tons and a displacement of 129,000 tons. ✦