By MONICA HATCHER and TOM FOWLER HOUSTON CHRONICLE
April 23, 2010, 12:44PM
Search and rescue efforts for 11 missing rig workers from the Deepwater Horizon that caught fire earlier this week and sank entered its third full day on today, with the U.S. Coast Guard saying it would continue the effort until night fall.
As hopes dimmed the missing employees would be found alive, Coast Guard Petty Officer Tim Atkeson said the search had been scaled back to a single helicopter and cutter that were still canvassing the Gulf waters.
The Deepwater Horizon, a semi-submersible rig owned and operated by Transocean and leased by BP, sank mid Thursday morning following a new explosion. For much of the day, the massive steel structure remained submerged below the waterline. It was unclear today whether the ten-year old rig had sunk to the bottom of the seabed some 5,000 feet below.
Coast Guard officials said the flow of oil from the undersea well had, at least for the time being, stopped on its own, since remote controlled submarines had been unable to shut equipment safety valves at the wellhead.
“This could just be temporary, so we’re not letting our guard down,” Senior Chief Petty Officer Mike O’Berry said.
BP and Transocean said they were also prepared to drill a second, relief well to intercept the open well if further efforts to seal it off were unsuccessful.
The rig also held 700,000 gallons of diesel fuel onboard at the time of the accident.
On the scene, six oil skimmer vessels with the capacity to hold between 3,000 and 5,000 gallons each remained at the ready. Several aircraft were flying over a rainbow sheen of oil that had spread from the area yesterday and were spraying dispersant chemicals that break up oil and cause it to sink.
One of the skimmers picked up about 180 barrels of oily water so far, an indication the flow of oil remains light. The slick that appeared on the water yesterday has grown slightly to 2 miles by 8 miles in size, Petty Officer Ashley Butler said. Butler said about 200 barrels oil are still on the surface, with about 40 percent of it expected to evaporate.
Coast Guard officials estimated under current conditions and with no intervention it would take nine days for the spill to reach the fragile Louisiana coastline.
“The Coast Guard is upbeat and positive that the spill will be contained before it gets that far,” Butler said.
BP and the Minerals Management Service said the rig would eventually be recovered, according to Atkeson.
“They are going to look into salvage and recovery measures when we’ve completed mitigating the oil spill and the oil we have on the surface,” Atkeson said.
Beau Bisso, president and chief executive of Bisso Marine, one of the nation’s largest marine salvaging companies said there was little that could be done to prevent the rig from sinking, after which it would be near impossible to lift from the ocean floor.
Divers that would be needed to secure the structure can only get down to about 2,000 feet, Bisso said.
“I would say the chances of salvaging that thing are zero,” Bisso said. “That’s an enormous undertaking to salvage something like that. It has never been done before. The magnitude of this is just enormous.”
At a mid-day press conference Thursday, the coast guard and company officials did not seem to think that the sinking of the rig would prevent an investigation from going forward.
Glenn Bolton, vice president of fire cause investigations for SEAL Corp., an oil field accident investigation and forensic engineering firm, said the fact that the rig had sunk may have helped preserve evidence that otherwise would have been totally consumed by the fire.
An investigation into the cause of the accident of Deepwater Horizon’s magnitude could take months, Bolton said. It would likely start with an investigation into why the blowout preventer failed and caused rig operators to lose control of the well.
A blowout preventer is a large safety valve that can seal off at the wellhead to stop the explosive release of pressurized oil and gas.
In the meantime, the Coast Guard said a remote operating vehicle was taking photos of the underwater rig as the situation was being assessed.
Houston Chronicle staff writer Matthew Tresaugue contributed to this report.