Washington (Platts)--17Feb2011/424 pm EST/2124 GMT

The National Oil Spill Commission released Thursday a lengthy report from its chief counsel that concludes the blowout preventer at BP's Macondo well was not "the root cause" of the accident that killed 11 people and sent millions of barrels of oil into the Gulf last year.

The report, from Chief Counsel Fred Bartlit, is the commission's strongest statement yet that the BOP, which many have said was the key piece of evidence in the accident investigation, was not to blame. Bartlit said that while the BOP's performance was "flawed," it did not cause the blowout.

"Even if the BOP had functioned flawlessly, the rig would have exploded and 11 men would have died," the report's executive summary said.

The new report also claims that BP knew of critical problems with the well design and the design of the cement job by Halliburton, but failed to address them.

Republicans in Congress, and some Gulf Coast Democrats, severely criticized the commission's final report, saying that it was incomplete because investigators had not physically examined the BOP, a five-story series of valves designed to seal a well in an emergency. The BOP is undergoing a forensic examination in Louisiana as part of a joint investigation being conducted by the Bureau of Ocean Energy Management, Regulation and Enforcement and the US Coast Guard.

At a hearing on January 26, congressmen blasted commission co-chairs William Reilly and Bob Graham, saying that their report did not find the cause of the accident and that no conclusions could be drawn about a cause until the examination of the BOP is complete.

Bartlit's report also concluded that BP's internal documents show it had problems with the Halliburton engineer assigned to Macondo "for years."

"But they neither reviewed his work at Macondo carefully, nor even checked to see that he conducted testing in a timely manner--even though they knew that their last-minute changes to the cement design test could cause problems and that using nitrogen foamed cement could pose 'significant stability challenges,'" the report stated.

Bartlit also said in the report that once the commission identified "serious concerns" with the Halliburton design for the cement job, the company stopped cooperating with the investigation.

"Halliburton refused to allow the team to conduct further interviews of its cementing engineer and lab personnel," the report stated. "Halliburton has not provided scientific data to support some of its technical assertions, and declined to provide documents regarding lab-testing protocols and evaluation criteria."

A Halliburton spokeswoman did not immediately respond to a request for comment.

--Gary Gentile, gary_gentile@platts.com

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