NEW ORLEANS — The oil rig that exploded, caught fire and then sank 36 hours later could lead to a major oil spill, officials said Thursday, and as a result a remotely operated vehicle is surveying the seas and assets ranging from aircraft to containment booms are ready to be deployed.
At a press conference, the officials also said hope was running out for 11 workers still missing after the blast Tuesday night off the coast of Louisiana. The Coast Guard said its search would probably continue into early Friday.
Crews searching for the workers have covered the 1,940-square-mile search area by air 12 times and by boat five times. The boats searched all night.
Carolyn Kemp said Thursday that her grandson, Roy Wyatt Kemp, 27, was among the missing. She said he would have been on the drilling platform when it exploded.
"They're assuming all those men who were on the platform are dead," Kemp said. "That's the last we've heard."
Officials had previously said the environmental damage appeared minimal, but new challenges have arisen now that the platform has sunk.
The well could be spilling up to 336,000 gallons of crude oil a day, the Coast Guard said, and the rig carried 700,000 gallons of diesel fuel.
Crude from the well had been burning off but when the rig sank earlier Thursday the fire was extinguished. What's not clear is if the crude is still spewing below the surface.
Coast Guard Rear Adm. Mary Landry said crews saw a one mile by five mile sheen of what appeared to be a crude oil mix on the surface of the water.
Boats that skim oil from the top of water are working in the area, she said.
Video: Oil rig sinks Landry did not have an estimate for when videotape from the remotely operated vehicle would be available to show if crude was spilling from the wellhead.
But the National Ocean Service's Office of Response and Restoration, which deals with oil spills, said it believes "crude oil and natural gas are being released uncontrolled from the riser pipe of the well," adding that "three attempts to shut-in the well have been unsuccessful."
Doug Helton, incident operations coordinator at the office, said any spill is not expected to come onshore for three to four days. "But if the winds were to change, it could come ashore more rapidly," he said.
The oil will do much less damage at sea than it would if it hits the shore, said Cynthia Sarthou, executive director of the Gulf Restoration Network. "If it gets landward, it could be a disaster in the making," Sarthou said.
At the worst-case figure of 336,000 gallons a day, it would take more than a month for the amount of crude oil spilled to equal the 11 million gallons spilled from the Exxon Valdez in Prince William Sound.
Oil giant BP, which was finishing an exploration well when the explosion happened, said it has mobilized four aircraft that can spread chemicals to break up the oil as well as 32 vessels, including a big storage barge, that can suck more than 171,000 barrels of oil a day from the surface.
Seventeen workers brought to shore Wednesday suffered burns, broken legs and smoke inhalation. Four were critically injured.
About 100 others who were not hurt had made it to a supply boat after Tuesday night's explosion, then were plucked from the Gulf of Mexico by Coast Guard rescuers.Video: Rescue crews describe scene
After a slow-moving trek across the waters, the workers finally made it ashore at Port Fourchon earlier Thursday where they were checked by doctors and brought to a hotel in suburban New Orleans to awaiting relatives.
"I've seen a lot of things, but I've never seen anything like that," said a visibly tired worker, who declined to give his name as he got in a car to leave.
The rig, where exploratory drilling was being done about 50 miles off the coast of Louisiana, exploded late Tuesday, sending workers scurrying for safety.
The rig is owned by Transocean Ltd. and was under contract to BP.
The 400-by-250-foot rig is roughly twice the size of a football field, according the Transocean's website.
A column of boiling black smoke rose hundreds of feet over the Gulf of Mexico on Wednesday as fireboats shot streams of water at the blaze.
Adrian Rose, vice president of Transocean, said the explosion appeared to be a blowout, in which natural gas or oil forces its way up a well pipe and smashes the equipment. But precisely what went wrong was under investigation.
A total of 126 workers were aboard. Seventy-nine were Transocean workers, six were BP employees and 41 were contracted.
A lawsuit filed Thursday, claimed the companies involved in the blast were negligent.
The lawsuit was filed in New Orleans on behalf of a Mississippi man who worked on the rig and is one of 11 people still missing.Slideshow: Oil spill disaster in the Gulf
The lawsuit claims Shane Roshto, of Amite County, Miss., was thrown overboard in the explosion and is feared dead.
A Transocean spokesman did not immediately respond to a request for comment and BP wouldn't discuss the suit.
Since 2001, there have been 69 offshore deaths, 1,349 injuries and 858 fires and explosions in the Gulf, according to the federal Minerals Management Service.
One of the deadliest U.S. offshore drilling accidents was in 1964, when a catamaran-type drilling barge operated by Pan American Petroleum Corp. near Eugene Island, about 80 miles off Louisiana, suffered a blowout and explosion while drilling a well. Twenty-one crew members died.
The deadliest offshore drilling explosion was in 1988 about 120 miles off Aberdeen, Scotland, in which 167 men were killed.
Rose said the Deepwater Horizon crew had drilled the well to its final depth, more than 18,000 feet, and was cementing the steel casing at the time of the explosion.
"They did not have a lot of time to evacuate. This would have happened very rapidly," he said.
According to Transocean's website, the rig was built in 2001 in South Korea and is designed to operate in water up to 8,000 feet deep, drill 5½ miles down, and accommodate a crew of 130. It floats on pontoons and is moored to the sea floor by several large anchors.
Workers typically spend two weeks on the rig at a time, followed by two weeks off. Offshore oil workers typically earn $40,000 to $60,000 a year — more if they have special skills.
Working on offshore oil rigs is a dangerous job but has become safer in recent years thanks to improved training, safety systems and maintenance, said Joe Hurt, regional vice president for the International Association of Drilling Contractors.
Stanley Murray of Monterey, La., was reunited with his son, Chad, early Thursday morning. His son, an electrician aboard the rig, had ended his shift just before the explosion.
"If he had been there five minutes later, he would have been burned up," a relieved Stanley Murray said.
The Associated Press contributed to this report.