BP launches bid to plug oil-well leak for all time

Tests were due to be carried out yesterday to determine whether the well can withstand mud and cement that will be shovelled into it.

If the tests were successful, the company planned to start the so-called "static kill" attempt today.

"It could be the beginning of the end," said Darryl Bourgoyne, director of Petroleum Engineering Research Lab at Louisiana State University.

When the static kill begins, crews will slowly pump heavy mud through lines installed last month straight down the throat of the leaky well. If the mud forces the oil back into the massive underground reservoir and scientists are confident the pressure remains stable, then engineers can pump in fresh cement to seal it.

The well has spewed as much as 184 million gallons since the rig connected to it blew up in April, killing 11 workers.

The mile-deep underground reservoir is currently temporarily sealed after a containment cap was placed over the well two weeks ago.

"The only thing that separates the oil from the sea now is the valve. This puts thousands of feet of mud and cement in between," said Eric Smith, associate director of the Tulane Energy Institute. "The idea is to have as many barriers as possible between the ocean and the reservoir."

The process of choking the underground reservoir feeding the well will involve pumping mud and then cement down an 18,000ft relief well. This is intended to plug up the source of the oil, not just its route to the sea.

The company tried a similar process, called a top kill, to choke the well with mud in May. It failed partly because the mud could not overcome the flow of the oil.

However, this time the oil is no longer freely flowing from the well, thanks to the temporary cap, meaning the engineers will not have to pump in mud with as much force.

There is a risk the pressure exerted by the mud will rupture the casing holding in the oil and potentially cause an even greater mess, but experts say that is unlikely.

"I can't imagine it failing. It's holding pressure and there's no indication of any loss of fluid from the well," said Mr Smith. "It's a vanishingly small risk of failure."

The procedure is still set to be completed by late August despite a brief evacuation for Tropical Storm Bonnie last week.

BP has faced fierce criticism in the US over its handling of the affair and last week confirmed the departure of under-fire boss Tony Hayward in October, to be replaced by American chief Bob Dudley.

It also revealed a 20.8 billion blow from the spill in second quarter figures and is now threatened with a drilling ban in the Gulf after US politicians passed a bill proposing to freeze the firm out of new drilling leases for seven years.

Meanwhile, environmental campaigners yesterday called on the government to halt BP plans to begin a deep drilling operation off the Shetland Islands.

The oil giant wants to drill to depths of 4,265ft in a field 60 miles west of the islands, and the operation is due to begin in October, subject to approval.

Greenpeace is calling for a US-style moratorium on deep sea drilling - a measure that UK ministers have so far ruled out.