BP: Series of Calamities Caused Gulf Oil Spill

(Sept. 8) -- BP has concluded that a "sequence of failures" by "multiple companies and work teams" led to the explosion and fire that killed 11 workers and triggered the world's largest accidental oil spill in the Gulf of Mexico earlier this year.

"No single factor caused the Macondo well tragedy," the oil giant said today on its website, where it released results of its internal investigation. The spill arose from "a complex and interlinked series of mechanical failures, human judgments, engineering design, operational implementation and team interfaces," it said.

Today's 193-page report, filled with complex technical explanations, factors large in how BP portrays itself in a legal "blame game" that's expected to carry on for months and possibly even years. It's based on a four-month investigation by BP's head of safety and operations, Mark Bly, and more than 50 other experts from inside and outside the company, BP said.

BP wasn't expected to take full blame in this report and has sought in public hearings to place more responsibility for the disaster on other companies from whom it leased the Deepwater Horizon oil rig or contracted work.

The rig exploded on April 20, killing 11 workers and injuring 17. It also started America's worst-ever oil spill, with the blown-out well spewing more than 200 million gallons of crude into the gulf and smearing U.S. coastlines.

On London markets, stock in BP rose 2 percent after the report's release, trading at around $6.41 a share. Part of the jump could be investor confidence in BP, because the report diverts more blame onto its contractors rather than the oil giant itself.

Attorneys suing BP said the report contains an impressive array of details about the disaster, but its overall conclusions do not differ significantly from BP's general story line, which has been known for months.

"If anybody expects this to be a true reflection of what really happened, it's not," said Kurt Arnold, who represents relatives of three of the workers who died and 17 who were injured. "It's the BP legal defense team's best face on it. This is basically their game plan for how they're going to defend themselves in court."

Arnold said he was especially dismayed that BP blamed the workers on the rig for reaching "the incorrect view" that pressure readings taken on the well were good.

Among the contractors to whom BP has sought to divert blame is Halliburton Co., which was paid to line the well hole with cement. Today's report says the cement materials "failed to contain hydrocarbons within the reservoir, as they were designed to do, and allowed gas and liquids to flow up the production casing."

"To put it simply, there was a bad cement job," BP's outgoing CEO Tony Hayward said in an accompanying news release.

As for employees of the rig owner Transocean Ltd., who actually drilled the oil well under BP supervision, they "failed to recognize and act on the influx of hydrocarbons into the well" for a full 40 minutes, until it was too late to avert an explosion, BP concluded.

BP also accepted some of the blame itself, noting that its engineers incorrectly accepted results from pressure tests that at closer look revealed that the well wasn't structurally sound.

Transocean and Halliburton dismissed the oil giant's conclusions as full of errors and omissions.

"This is a self-serving report that attempts to conceal the critical factor that set the stage for the Macondo incident: BP's fatally flawed well design. In both its design and construction, BP made a series of cost-saving decisions that increased risk – in some cases, severely," Transocean said in a statement e-mailed to AOL News.

Transocean ticked off a five-point itemized list of decisions "made exclusively by BP" that include neglecting to run a cement bond to test the integrity of the cement and failing to conduct a complete "bottoms up" circulation of the well, ensuring the quality of the cement seal.

The company added that its own investigation of the incident continues and awaits "critical information the company has requested of BP but has yet to receive."

Halliburton did not offer a specific rebuttal, although it said in a statement that the report contains "substantial omissions and inaccuracies."

It noted that the "well owner is responsible for designing the well program and any testing related to the well. Contractors do not specify well design or make decisions regarding testing procedures."

One of the most important findings today centers on how the well malfunctioned in the moments before the April 20 explosion. BP concludes that the force of the blast flew up the well's main pipe and not outside its casing, in the so-called annulus. That supports the idea that failures were not in BP's well design but instead in how it was carried out.

"Based on the report, it would appear unlikely that the well design contributed to the incident, as the investigation found that the hydrocarbons flowed up the production casing through the bottom of the well," Hayward said.

The company has made 25 recommendations to ensure such an accident doesn't happen again. Among them, establishing new cementing guidelines and updating minimum requirements for the configuration of blowout preventers -- one of the many key pieces of equipment that failed to stop the April 20 rupture.

The Deepwater Horizon's broken blowout preventer was hauled out of the water last weekend and is being transferred to a NASA facility in New Orleans where government investigators plan to analyze it. That crucial evidence wasn't part of BP's probe, which is also being followed by similar investigations from a host of government agencies and corporate entities.