Engineers struggle with failed blowout valves

The Deepwater Horizon rig that exploded 80 kilometres from the Louisiana coast included a series of valves on the seabed designed to prevent a well blowout. For reasons that are still unclear, the blowout preventer didn't work when the well exploded on April 20 and the rig burst into flames.

A spokesperson for Cameron International Corp., the Houston company that supplied the blowout preventer, said Friday that he was unable to explain exactly how the equipment works.

"All of our guys who are experts on that are at the well," said Scott Amann, vice-president of investor relations.

British-based BP, the companythat leases the rig and operates it, did not immediately return calls.

Meanwhile, six remotely controlled submarines have so far failed to reactivate the valves in the blowout preventer. Now engineers are working onshore to build a dome that will be placed over the leak to collect the spewing oil and funnel it to the surface for treatment.

The system is designed for shallow water and this marks the first time anyone has tried to adapt it for deep water. BP said in a news release that it could be four weeks before the dome system is functioning.

BP is also working on an even longer-term solution. It has already moved a drilling platform to the area and plans to drill a relief well that will decrease pressure on the original well and inject a sealant into the well to plug it. That effort is expect to take two to three months, the company says.