BP said last night that oil has stopped leaking into the Gulf of Mexico for the first time since April.
BP has been slowly dialling down the flow as part of a test on a new cap. Engineers are monitoring the pressure to see if the busted well holds.
The operation was delayed because they first had to fix a leaking hose on the new device. The main test involves closing all three openings in the cap.
BP expects to keep the oil trapped for 48 hours before it decides if the approach is working.
The cap – a 75-tonne metal stack of lines and valves – was lowered on to the well on Monday in the hope of either bottling up the oil inside the well or capturing it and funnelling it to the surface.
Retired Coast Guard admiral Thad Allen, the US government’s representative, said a committee of scientists and engineers would monitor the results and assess them every six hours, and end the test after 48 hours to evaluate the findings.
Mr Allen said the tests would also give an insight into the other, more permanent, solution to the leak – two relief wells.
The mapping of the sea floor to prepare for the well-cap test and the pressure readings will also help determine how much mud and cement will be needed to seal off the well.
BP plans to use the relief wells to kill the leak permanently by mid-August.
Arbuthnot Securities analyst Dougie Youngson said: “There is quite a lot of nervousness about how effective this cap is going to be and whether it might, in fact, make matters worse.
“There is a very high degree of uncertainty over which way this is going to go.”
The crisis began on April 20 when the BP-leased Deepwater Horizon rig exploded, killing 11 workers. In the 12 weeks since, up to an estimated 182million gallons of oil have flowed into the gulf.
Oil and gas producer Apache Corporation is seeking £3.9billion-£4.5billion in order to buy up to £6.5billion in assets from BP in a deal that could be announced next week, US media reported yesterday. It is thought the deal could include major BP assets in Alaska.
Beleaguered BP has said it could sell £6.5billion in assets to raise funds to cover liabilities from the gushing Gulf of Mexico oil well. Spokesmen for BP and Apache declined to comment.
The Duke of York yesterday visited BP’s North Sea headquarters in Aberdeen, where he met senior management and staff. He spent nearly two hours in the building and was briefed on the company’s long-term plans for continued high levels of North Sea investment and the situation in the Gulf of Mexico.