Oil tanker strikes missing rig in Gulf of Mexico

May 19, 2009 12:00 AM

A 900-foot oil tanker was damaged when it struck a submerged jackup rig that had been missing since Hurricane Ike. The SKS Satilla began taking on water March 8 after being holed by the wayward rig Ensco 74 in the Gulf of Mexico about 65 miles south of Galveston, Texas. The ship reported an 8° port list as a result of the breach.

The ship's Norwegian owner, SKS Obo & Tankers AS, responded along with the U.S. Coast Guard and other federal and Texas state agencies. Satilla's entire load had to be removed at sea.

"Thanks to the efforts of a unified command, comprised of multiple agency representatives and maritime experts, over 41 million gallons of oil were safely offloaded from the ship and the vessel will transit to a shipyard to make repairs," said Cmdr. James Elliott, commanding officer of Coast Guard Marine Safety Unit Galveston.

An environmental disaster was averted because the vessel had a double-bottom hull, the Coast Guard said. Although the vessel's outer hull was significantly breached, the inner hull remained intact containing all of the oil. SMIT Salvage inspected the area using its vessel Northern Canyon, equipped with a remotely operated vehicle to retrace the tanker's course. Satilla had damage to a large area on its port side, below the waterline.

The rig had been blown more than 110 miles west of its last known location. Ensco 74 is owned by Ensco International Inc. of Dallas. The rig was working off the Louisiana coast when Hurricane Ike came through Sept. 13, 2008, and ripped it from its moorings.

It was the only one of Ensco's 13 rigs in the area that went missing. Because its location was unknown, it was not marked on charts and was invisible to mariners. A marker buoy has since been placed there, the Coast Guard said. The accident happened within a few days of the 20th anniversary of the grounding of Exxon Valdez. By comparison, Exxon Valdez spilled only 11 million gallons of crude, but managed to pollute 1,100 miles of Alaskan coastline. Because of the Exxon Valdez incident, Congress ordered a phase-out of single-hulled oil tankers. The Coast Guard said SKS Satilla's double hull prevented the escape of the oil.

AET Shipmanagement's Eagle Albany lightered all 41 million gallons of oil from the vessel. Minor repairs were carried out by underwater divers while the tanker was at anchor. This included the removal of a piece of metal from the SKS Satilla's port ballast tank. The ship later sailed to Portugal, where it was dry-docked to make permanent repairs.

Now that the rig has been located, Ensco is responsible for its removal. The Ensco 74 is approximately 24 feet below the surface of the water. A team consisting of the Coast Guard Marine Safety Unit Galveston and representatives of Ensco in April were working on a salvage plan to recover the drilling rig.

"All hydrocarbons have been removed from the rig and work continues on the salvage aspect of the plan," said Lt. Tim Tilghman, of the Marine Safety Unit.

SKS Satilla, built in 2006 in South Korea, is a Suezmax tanker.

Ensco 74 was built by the AMFELS Shipyard in Brownsville, Texas, in 1999. It could work in 375 feet of water and could drill to a depth of 30,000 feet. •

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