BP could begin sealing its oil well in the Gulf¹ of Mexico on Monday night, three months after its rupture² led to the worst oil spill in US history.

英国石油将于本周一晚上封锁墨西哥湾海底油井，该油井泄露长达三个月，是美国历史上最严重的漏油事故。

Thad Allen defended the use of chemical dispersants by BP to break up oil slicks

The US official overseeing（监督，审查） the federal response said engineers were preparing to pump mud and cement（水泥） into the well in a procedure known as a "static kill".

Mud and cement would then be pumped in from a relief well below five to seven days later, Admiral Thad Allen said.

Only that "bottom kill" would fully⁴ seal it, he said.

The well has been temporarily sealed for two weeks after spilling up to 60,000 barrels of oil a day into the sea since 20 April, when an explosion on a drilling rig（钻探装置） off Louisiana killed 11 workers and triggered the leak.

Last week, BP reported a record $17bn (£11bn) loss, having set aside $32bn to cover the costs of the spill.

The oil has caused an environmental disaster and devastated⁵ coastal⁶ communities in four US states.

'Bottom kill' crucial

Speaking to reporters on Sunday, Adm Allen said the two-pronged strategy to seal the well once and for all "could start as early as Monday night", depending on the results of ongoing⁷ tests.

The static（静态的） kill, also known as "bullheading", would see two ships pump heavy drilling mud into the well.

The mud would enter through lines installed earlier this month on top of the blowout preventer（防喷器） , the unit that failed when the rig exploded.

In theory the mud should force the oil and gas back into the reservoir（水库，蓄水池） below the seafloor. If pressure in the well remains⁸ stable and no unknown leaks are discovered, cement will then be poured in to seal the top of the well pipe.

An earlier effort to pump mud into the well using much of the same equipment at the end of May failed because the pressure of the spewing oil and gas was too great.

Adm Allen said he would travel to BP's headquarters in Houston to oversee³ the static kill, and that engineers would know within hours if was successful.

But it is the bottom kill, where mud and cement will be pumped through a newly drilled relief well into the bottom of the leaking well, which is needed to seal it completely.

"The static kill is not the end-all, be-all," Mr Allen said, downplaying the significance of the first part of the strategy.

If any leaks are detected during the procedure over the coming days, technicians will seek to identify them through seismic⁹（地震的） work and other diagnostic testing.

The leaks will then be plugged during the bottom kill, an operation officials say is not expected to be completed until late August.

During Sunday's news conference, Mr Allen also defended the use of chemical dispersants（分散剂） by BP to break up oil slicks created by the spill, despite widespread concerns expressed about their environmental impact.

"Sometimes there is no other way to attack the oil," he said, denying he had clashed with the head of the Environmental Protection Agency over the matter.

"There is no disagreement between Lisa Jackson and I regarding what we want to do with dispersants. This really is an issue of making decisions day-to-day based on where the oil is at out there," he added.