New Orleans, La. – Crews lowered the 100-ton concrete and steel dome over the leak a mile underwater. But it's now off to the side on the seabed while engineers come up with some solution to the crystals forming in the cold water.
BP executive Doug Suttles says the next few days are critical.
"The issue is how to keep them forming again. That's the big challenge."
Another possibility being reviewed is plugging up the leaking well with rubber and other materials. But Suttles says high pressure at that depth could make it worse.
"It's very difficult to predict whether we'll find solutions."
BP is also continuing to drill a relief well to cut off the flow of oil estimated at 210,000 gallons a day. That could take three months.
For NPR News, I'm Eileen Fleming in New Orleans