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Petronius Platform

The Petronius Platform is a deepwater oil rig operated by ChevronTexaco and Marathon Oil in the Gulf of Mexico, 210 km South-east of New Orleans.

A compliant piled tower design, it is 610 m (2,001 feet) high, the tallest free-standing structure in the world. The multi-deck topsides are 64 m by 43 m by 18.3 m high and hold 21 well slots, the entire structure weighs around 43,000 tons. Around 50,000 barrels of oil and 70 million cubic feet of natural gas are extracted daily by the rig.

The platform is situated to exploit the Petronius field, discovered in 1995 in Viosca Knoll and named after the Roman philosopher. The sea bed is 535 m (1,754 feet) below the platform. The compliant tower design is more flexible than conventional land structures to cope better with sea forces. It can deflect in excess of 2% of height. Most buildings are kept to within 0.5% of height in order to have occupants not feel uneasy during periods of movement.

Construction began in 1997 by J Ray McDermott with the seabed mooring system. The contract for the platform was budgeted at $200 million with total costs of around $500 million. The 4,000-ton North Module was installed in November 1998, but the attempt to install the slightly lighter South Module in December of that year ended with the unit on the seabed. A replacement module was built and installed in May 2000.