Chemist: Ice-like crystals that blocked oil-leak capture are as buoyant as ice cubes

NEW ORLEANS (AP) — A petroleum chemist and geologist says the icy hydrates that have halted an effort to slow the Gulf oil spill can float like ice cubes and can form less than a quarter-mile from the surface.

Authorities said Saturday those hydrates clogged the giant box that crews were trying to put over the leaking well nearly 5,000 feet deep.

Art Johnson, chief of exploration for Hydrate Energy International, said hydrates form when gases such as methane mix with water under high pressure and cold temperatures. That can happen at 1,200 feet and lower.

Johnson said he had been worried that hydrates might form in the four-story containment box. He says crews might have to lift the 100-ton box off of the ocean floor and bring it shallow enough to melt the ice-like crystals.