BP 'in a good place' as Gulf oil spill is finally halted

• These oil-affected pelicans that have been treated at a Florida bird centre will be released back into the wild today. Picture: Getty Images

But the United States government stopped just short of pronouncing the well dead, as BP continued to pump cement in from the bottom of the wellhead to seal it off for good.

After months of living with lost income, fouled shorelines and dying wildlife, some Gulf Coast residents were not so sure.

Yet it appeared there might finally be an end in sight to the disaster that closed vast fishing areas, interrupted the usually lucrative tourist season, and cost BP's chief executive his job and the company's shareholders billions of pounds.

BP said 2,300 barrels of mud forced down the well overnight - in an operation called a "static kill" - had pushed the crude back down to its source for the first time since the Deepwater Horizon exploded off Louisiana on 20 April The blast killed 11 workers and began the spill that sent tar balls washing on to beaches and oil oozing into delicate coastal marshes.

Engineers then forced cement down the well after receiving approval from National Incident Commander Thad Allen, on the condition it did not delay work on a relief well.

There was more seemingly good news when an official report said only about 30 per cent of the spilled oil remained in the Gulf, and it was degrading quickly. The rest had been contained or cleaned up or otherwise disappeared. The report said the oil no longer posed a threat to the Florida Keys or the east coast.

But some independent experts said they were concerned that the government's method of estimating the amount was too simple for such a complex spill - and even government scientists warned the rosy numbers did not mean the Gulf was out of harm's way.

Government officials said they would not declare complete victory until mud and cement was pumped in from the bottom to seal the well, a procedure that might not be done for weeks.

"We're in a good place today, but we want to get it permanent over the near term, whether that's days or weeks," said Kent Wells, BP senior vice-president, who avoided saying the static kill had finished the job. Asked when he would be able to say the well was dead, he replied: "I'm looking forward to that day."

An experimental cap had stopped the oil from flowing for the past three weeks, but it was not a permanent solution. Before the cap was lowered, the government estimated 172 million gallons of oil had flowed into the Gulf.

Before that, BP had tried a series of often absurd sounding contraptions, raising hopes only to dash them when those efforts failed. They included a giant 100-ton containment box that got clogged with ice-like crystals and the so-called junk shot, an attempt to clog up the well with golf balls and rubber scraps.

The apparent success of the static kill had some people along the Gulf coast curious about why BP had waited so long to try it.

But the static kill - also known as bullheading - probably would not have worked without the cap in place. It involved slowly pumping the mud from a ship down lines running to the top of the ruptured well a mile below; a similar effort failed in May when the mud could not overcome the flow of oil.

Even politicians expressed concern that BP and the US government would need to stay focused on the clean-up and long-term monitoring of the Gulf's marine life. "This is a positive step," said Louisiana governor Bobby Jindal. "But this crisis is not over for Louisiana until the well is permanently capped and our coasts and wetlands are fully restored to their pre-spill status and our people can resume their way of life."

WHAT HAPPENED TO THE OIL

An ESTIMATED 4.9 million barrels of oil have escaped into the Gulf of Mexico over 87 days.

This is a breakdown of what has happened to it:

17% has been removed from the leak site by insertion tube and top hat system

5% has been burned off

3% has been skimmed

25% has evaporated or dissolved

16% has dispersed naturally

8% has been dispersed by chemicals

26% is still at sea or on shore

Source: US National Oceanic and Atmospheric Administration.

BP 'in a good place' as Gulf oil spill is finally halted - by mud and cement