By OGJ editors
HOUSTON, Feb. 5 -- A 38-year-old production platform operated by a unit of Total SA that sank of the Gulf of Mexico in September 2002 has been removed. Hurricane Lili, a Category 4 hurricane packing 140 mph winds, toppled the structure in 180 ft of water as it was undergoing decommissioning and removal from Eugene Island 275A some 70 miles off Louisiana (OGJ Online, Oct. 22, 2002). During the storm, the deck had broken free of the jacket and rested upright on the seabed.
Total secured a Special Artificial Reef Site permit to leave part of the platform on location, and Stolt Offshore Ltd., Houston, which conducted salvage operations, worked nonstop, removing enough of the jacket structure and equipment to ensure a minimum clearance of 85 ft from the surface of the water for safe navigation purposes. It also removed equipment that could still contain hydrocarbons, flooded other empty vessels on deck, and completed plugging and abandonment of the remaining four wells. No pollution occurred, Stolt Offshore said, because of the abandonment operations that had been performed before the storm hit.
Stolt Offshore completed salvage operations within 60 days of initiation, using what it described as the "first platform salvage using only mechanical cutting devices."
The remotely operated tools had to sever 42-in. x 0.5-in. jacket legs with 39-in. x 0.75-in. grouted piles as well as 8-in. diameter jacket members. One of the hydraulic shears, originally designed to cut concrete piles, produces 750,000 psi of cutting force, Stolt Offshore said.
Stolt Offshore's DLB 801 derrick laybarge was the primary vessel for these operations, its 900-ton main crane and deck crawler crane used to deploy the cutting tools and to recover the severed jacket members and well casings. The company's Triton ST ROV remote operating vehicle worked almost nonstop, and about 150 employees worked 24 h/day, 7 days/week to complete the task.
