Shell Exploration & Production Co. Shell’s Mars Platform was the largest platform repaired in the Gulf of Mexico after Hurricane Katrina.

The amount is a fraction of the estimated $5 billion-plus in expected work, some of it the most complex the industry has ever faced, says Lars Herbst, Gulf of Mexico regional director for MMS, a unit of the U.S. Dept. of the Interior that oversees offshore oil and gas leasing. Only 20% of the 118 storm-damaged platforms have been removed, and about 40% of the wells have been sealed, he says. MMS anticipates a great deal of activity to take place this year.

“There is certainly a lot of work to be done,” says Bob Byrd of Twachtman Snyder & Byrd Inc., a Houston-based firm specializing in platform decommissioning. TSB is doing some of the work but cannot reveal its clients, Byrd says. TSB will be doing hurricane-cleanup work for at least three more years, he adds. Houston-based Versabar Inc. has contracts to lift or decommission about a dozen of the platforms this summer using its Bottom Feeder lifting system.

Multimedia: Podcast: Lars Herbst: Oil and Gas Cleanup In the Gulf of Mexico

Decommissioning these platforms has been slow in part because resources have been focused on repairing platforms. That work is now finished, Herbst says.

The largest of those jobs was fixing Shell’s Mars platform, 130 miles south of New Orleans. Hurricane Katrina’s winds toppled the platform’s drilling rig and halted its 258,000-barrels-per-day production for nine months. The repaired rig was reinstalled in spring 2006. Shell has completed work on all of its damaged platforms at a cost of about $200 million, a Shell spokesman says.

Superior and its subsidiary, Houston-based Wild Well Control, were awarded the fixed-price $750-million contract by BP plc, Chevron Corp. and Apache Corp. to decommission seven jointly owned platforms in the Gulf of Mexico south of Port Fourchon, La., in water depths from 85 ft to 135 ft. To do the work, the companies must first plug 59 wells that fed the platforms. The companies expects the work to last three years.

The platforms were “totally destroyed by the hurricane,” says BP spokeswoman Marti Powers. “Everything is on the ocean floor.” An internal BP team is working to decommission its other damaged platforms, which were bent by the winds and waves, she says. Chevron also is working with its own internal team to decommission its destroyed platforms, a company spokeswoman says.

As the storm’s winds and waves bent the platforms, the pipes that cased the wells also were often bent. Automatic shutoff valves prevented major oil leaks. Debris over the wells must be cleared and the pipes straightened or replaced before the wells can be plugged, filled and capped, Byrd says.

In the most extreme cases, a company must drill a new well and vertically access the old well to plug it, Herbst says. The difficult conditions are costing companies up to 15 times more than standard decommissioning, he says.

“These platforms were certainly never intended to be removed from the bottom,” says Byrd of TSB. “It creates a difficult and inconvenient process.”