Deep-sea ice crystals halt attempt to shut off Gulf oil leak with box

ON THE GULF OF MEXICO -- A novel but risky attempt to use a 100-ton steel-and-concrete box to cover a deep-sea oil well gushing toxic crude into the Gulf of Mexico was aborted Saturday after ice crystals encased it, an ominous development as thick blobs of tar began washing up on Alabama's white sand beaches.

The setback left the mission to cap the ruptured well in doubt. It had taken about two weeks to build the box and three days to cart it 50 miles out then slowly lower it to the well a mile below the surface, but the frozen depths were too much for it to handle.

Still, BP officials overseeing the cleanup efforts were not giving up just yet on hopes that a containment box could cover the well and be used to capture the oil and funnel it to a tanker at the surface to be carted away. Officials said it would be at least Monday before a decision was made on what next step to take.

"I wouldn't say it's failed yet," BP chief operating officer Doug Suttles said. "What I would say is what we attempted to do ... didn't work."

There was a renewed sense of urgency as dime- to golfball-sized balls of tar began washing up on Dauphin Island, three miles off the Alabama mainland at the mouth of Mobile Bay and much farther east than the thin, rainbow sheens that had so far arrived sporadically in the Louisiana marshes.

"It almost looks like bark, but when you pick it up it definitely has a liquid consistency and it's definitely oil," said Kimberly Creel, 41, who was hanging out and swimming with hundreds of other beachgoers.

A long line of materials that resembled a string of pompoms were positioned on a stretch of the shore. Crews walked along the beach in rubber boots, carrying trash bags to clear debris from the sand.

Brenda Prosser, of Mobile, said she wept when she saw the workers.

"I just started crying. I couldn't quit crying. I'm shaking now," Prosser said. "To know that our beach may be black or brown, or that we can't get in the water, it's so sad."

Prosser, 46, said she was afraid to let her 9-year-old son, Grant, get in the water, and she worried that the spill would rob her of precious moments with her own child.

"I've been coming here since I was my son's age, as far back as I can remember in my life," Prosser said.

In the three weeks since the Deepwater Horizon rig exploded on April 20, killing 11 workers, about 210,000 gallons of crude a day has been flowing into the Gulf. Until Saturday none of the thick sludge -- those iconic images of past spills -- had reached Gulf shores.

It was a troubling turn of events, especially since the intrepid efforts to use the containment box had not yet succeeded. There has been a rabid fascination with the effort to use the peaked box the size of a four-story house to place over the ruptured well. It had taken more than 12 hours to slowly lower it to the seafloor, a task that required painstaking precision to accurately position it over the well or it could damage the leaking pipe and make the problem worse.

It was fraught with doubt and peril since nothing like it had been attempted at such depths with water pressure great enough to crush a submarine. It ended up encountering an icy crystals, familiar territory for deepwater drilling.

The icy buildup on the containment box made it too buoyant and clogged it up, BP's Suttles said. Workers who had carefully lowered the massive box over the leak nearly a mile below the surface had to lift it and move it some 600 feet to the side. If it had worked, authorities had said it would reduce the flow by about 85 percent, buying a bit more time as a three-month effort to drill a relief well goes on simultaneously.

Company and Coast Guard officials had cautioned that icelike hydrates, a slushy mixture of gas and water, would be one of the biggest challenges to the containment box plan, and their warnings proved accurate. The crystals clogged the opening in the top of the peaked box like sand in a funnel, only upside-down.

Options under consideration included raising the box high enough that warmer water would prevent the slush from forming, or using heated water or methanol to prevent the crystals from forming.

Steve Rinehart, a BP spokesman in Mobile, Ala., said late Saturday a second containment device was under construction by Wild Well Control, Inc., in Port Fourchon, La., the company that built the first one.

"It's the same general idea and approach. It may be a slightly different size and shape," he said.

Even as officials pondered their next move, Coast Guard Rear Adm. Mary Landry said she must continue to manage expectations of what the containment box can do.

"This dome is no silver bullet to stop the leak," she said.

The captain of the supply boat that carried the precious cargo for 11 hours from the Louisiana coast earlier last week wasn't giving up hope.

"Everybody knew this was a possibility well before we brought the dome out," Capt. Demi Shaffer, of Seward, Alaska, told an Associated Press reporter stationed in the Gulf in the heart of the containment zone with the 12-man crew of the Joe Griffin. "It's an everyday occurrence when you're drilling, with the pipeline trying to freeze up."

The spot where Deepwater Horizon rig once was positioned is now teeming with vessels working on containing the well. There are 15 boats and large ships at or near the site -- some being used in an ongoing effort to drill a relief well, another with the crane that lowered the containment device to the seafloor.

There is even a vessel at the site called the Seacor Lee that is sending a live video feed from the undersea robots back to BP's operations center in Houston.

"Everyone was hoping that that would slow it down a bit if not stop it," said Shane Robichaux, of Chauvin, a 39-year-old registered nurse relaxing at his vacation camp in Cocodrie, La. "I'm sure they'll keep working on it `til it gets fixed, one way or another. But we were hopeful that would shut it down."

The original blowout was triggered by a bubble of methane gas that escaped from the well and shot up the drill column, expanding quickly as it burst through several seals and barriers before exploding, according to interviews with rig workers conducted during BP PLC's internal investigation.

Deep beneath the seafloor, methane is in a slushy, crystalline form. Deep sea oil drillers often encounter pockets of methane crystals as they dig into the earth.

As the bubble rose up the drill column from the high-pressure environs of the deep to the less pressurized shallows, it intensified and grew, breaking through various safety barriers, said Robert Bea, a University of California Berkley engineering professor and oil pipeline expert who detailed the interviews to an Associated Press reporter.

"A small bubble becomes a really big bubble," Bea said. "So the expanding bubble becomes like a cannon shooting the gas into your face."

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Larimer reported from Mobile, Ala. Associated Press writers Ray Henry and John Curran in Louisiana, and Noaki Schwartz in Los Angeles contributed to this report.