Robots toil on sea bed to shut off oil spill

BP's soaring first-quarter financial results were overshadowed yesterday by concerns over the environmental fallout from the Deepwater Horizon oil rig disaster which claimed 11 lives off the coast of Louisiana at the weekend.

The Deepwater Horizon, an exploration rig operated by Transocean under contract to BP, sank into the Gulf of Mexico on Saturday, four days after an unexplained explosion.

The oil slick is more than 48 miles long and 39 miles wide, and BP is part of a massive effort to shut down the well head, which is pumping 1,000 gallons of oil into the sea every day.

The well was fitted with a "blow-out preventer", designed to close off automatically in response to a sudden change in pressure. But the safety mechanism failed to activate. The reasons for the explosion and the failure of the mechanism are being investigated.

In an effort to stem the flood of oil threatening sealife and heading for the coast of the United States, BP has five undersea robots, 5,000 feet down on the floor of the Gulf, attempting to close the preventer mechanically. The work has been underway since Sunday, and is expected to take another 24 to 36 hours to complete.

It is not clear whether the attempt to shut off the well manually will be successful. In parallel, BP is designing and engineering a "dome" to be fitted to the top of the well, in case the blow-out preventer cannot be activated. But the process could take as much as two weeks. Meanwhile BP has two massive drilling rigs – one already on site, another on its way – which will drill new wells nearby in an attempt to re-route the oil and stop the spill.

The company has committed 32 vessels to the clean-up operation, including skimmers to try to take off the contaminated top layer. It is deploying five aircraft to spray dispersant over the widening slick. So far, some 100,000 gallons of dispersant – a third of the world's supply – has been commandeered.