BILOXI, Miss. — Efforts to cap a leaking oil well in the Gulf of Mexico suffered a major setback Saturday, after ice-like crystals clogged the inside of a massive dome meant to contain an 18-day-long spill.
The crystals forced officials to move the steel-and-concrete dome, which is still on the sea bed, some 650 feet away from the well — and to scramble to find ways to stop the water-and-gas crystals from forming.
"I wouldn't say it failed yet," said Doug Suttles, chief operating officer of BP, the London-based company that owns the leaking well. "What I would say is what we attempted to do last night didn't work."
He kept expectations low, however. "It's very difficult to predict whether we will find solutions," he said.
Sign Up and Save
Get six months of free digital access to The Sacramento Bee
The dome was considered the best short-term solution to stop much of the spill. Engineers had hoped to contain 85 percent of the estimated 210,000 gallons gushing daily from the well by funneling oil to the surface from the dome, which is really a 78-ton box with a pyramid on the top. The 40-foot box took about two weeks to build.
The crystals, which are called hydrates and resemble slush, obstructed the flow of the oil, Suttles said. They also made the dome too buoyant, which prevented it from settling deeply into the seabed to form a water-tight seal.
Hydrates form when gas and water mix at low temperature and high pressure, as occurs at the bottom of the sea. The water temperature at the wellhead is about 42 degrees, with pressures in excess of 2,300 pounds per square inch. Pressure on the surface of the water is about 14 pounds per square inch.
Suttles said experts will spend the next few days looking at possible solutions, while other efforts continue to control the spill. A relief well intended to intercept the leaking one and seal it won't be completed for perhaps three more months.
The Deepwater Horizon oil rig, owned by the Transocean offshore drilling company, exploded April 20 about 50 miles off the Louisiana coast.
On Saturday, Suttles confirmed that six BP employees were among the 126 people on board the rig when it exploded and that they'd been there to discuss safety after the rig had gone more than 2,500 days without a significant accident.
"This rig had an outstanding record," Suttles said.
Eleven people were killed in the explosion, all employees of Transocean. The BP employees escaped safely, Suttles said.
Suttles had warned all week that problems could arise with the dome plan, which had never before been carried out at the depth of the leaking oil well, 5,000 feet below the surface of the Gulf of Mexico.
BP officials had specifically cautioned that crystals would be a challenge and had hoped that pumping water down a hose into the dome would keep its temperature high enough to prevent crystals from forming.
Suttles said it is easy enough to unclog the dome — the crystals melt when the box is lifted higher in the water. The trick, however, is to keep the gas and water from crystallizing while the box is on the sea bed, where it must be to capture the leaking oil.
There might be ways to do that. Options include using more heat or injecting methanol, which is often used as a solvent, into the box, he said.
Meanwhile, a Coast Guard official reported tar balls believed to be from the spill were washing up on an Alabama barrier island.
About half a dozen of the balls had been collected by Saturday afternoon at Dauphin Island, though the substance of the balls still needs to be tested.
More than 60 miles west, a representative from Biloxi's Ship Island Excursions said people were taking ferries Saturday to Ship Island, loaded with beach equipment for a day of fun in the sun.
"The beaches are beautiful and the water's great," Kevin Buckel said. He said no signs of oil were reported during their two trips out Saturday, and he expected the same results Sunday.
''We're hoping for the best," he said.
Nearly 1 million feet of oil-absorbing boom has been placed along gulf shores in hopes of blocking the oil from reaching land, Suttles said.
About 2.1 million gallons of an oil-water mix — about 90 percent water — has been collected since the spill began, the Coast Guard said Saturday, and almost 290,000 gallons of dispersants have been used to break up the oil on the water's surface.
"I don't think any of us know at this time what the impacts will be on the environment or the economic issues associated with this spill," said Coast Guard Rear Adm. Mary Landry, who is helping coordinate the federal response to the spill.
Friday's calm weather allowed for five successful burns of oil on the water's surface, but more burns were unlikely due to inclement weather over the weekend.
Suttles said a hotline has received more than 35,000 calls from people about the spill, more than half of them asking to help.
The Coast Guard and the Minerals Management Service of the U.S. Interior Department will begin a joint investigation Tuesday to identify the factors leading to the explosion and oil spill. Public hearings for the investigation will be held Tuesday and Wednesday in Kenner, La., a New Orleans suburb.
Congressional committees also have announced they'll hold hearings on the spill next week.
(Melton, of the Sun Herald, reported from Biloxi, Miss.; Mazzei, of The Miami Herald, reported from Miami. Christina Veiga of The Miami Herald contributed to this report.)
MORE FROM MCCLATCHY
For full McClatchy oil spill coverage, click here.
Follow McClatchy on Twitter.