After nearly five months of effort, federal officials announced that the Macondo 252 well that spewed nearly five million bbl of oil into the Gulf of Mexico is officially dead.

"With the successful first intercept by the relief well and our confirmation through pressure tests that the cement plugs are secure, we can now declare BP's Macondo well effectively dead," said Interior Secretary Ken Salazar and Energy Secretary Steven Chu.

"Though our source control mission is complete, President Obama has made it clear the administration will not rest until all the oil is cleaned up and the Gulf Coast is restored," they said.

The oversight of the well -- and its continuing decommissioning -- now transitions to the Bureau of Ocean Energy Management, Regulation and Enforcement from the National Incident Command.

BP plc said the casing and annulus of the well were sealed by cement. In oilfield terms, the annulus is a space between two concentric objects, such as between the wellbore and casing or between casing and tubing, where fluid can flow. BP operated the Deepwater Horizon rig that exploded and sank off the coast of Louisiana on April 20, killing 11 workers (see Daily GPI, April 22).

This is the "final step in a complex and unprecedented subsea operation -- finally confirming that this well no longer presents a threat to the Gulf of Mexico," said Tony Hayward, who was removed as the company's CEO due to his mishandling of public relations following the well blowout (see Daily GPI, July 28). "However, there is still more to be done. BP's commitment to complete our work and restore the damage done to the Gulf of Mexico, the Gulf Coast and the livelihoods of the people across the region remains unchanged," he noted.

BP reported that no volumes of oil have been recovered from the surface of the Gulf since July 21, and that the last controlled burn operation took place on July 20.

In early August BP brought the Macondo well under control via a procedure known as static kill, which involved the pumping of heavy drilling mud into the well from vessels on the surface (see Daily GPI, Aug. 6). But the two relief wells -- which were drilled at angles to intercept the Macondo well annulus -- were the ultimate solution to kill and permanently cement the well.

BP said it will now proceed to complete the abandonment of the Macondo well, which includes removing portions of the casing and setting cement plugs.

As of Friday, BP estimated that the cost of the response at $9.5 billion. This includes the cost of the spill response, containment, relief well drilling, static kill and cementing, grants to the Gulf states, claims paid and federal costs.

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