BP released a 193-page internal report this morning, based on a four-month investigation into the explosion on April 20 that spilled almost 5 million barrels of oil into the Gulf of Mexico. "No single factor caused the Macondo well tragedy," says BP. "Rather, a sequence of failures involving a number of different parties led to the explosion and fire which killed 11 people and caused widespread pollution in the Gulf of Mexico earlier this year." Drawing attention away from itself and toward contractors like Transocean, which owned the the rig, and Halliburton, which did cement work on the well, the BP report concludes that decisions made by “multiple companies and work teams” contributed to the accident. The report, conducted by a team of 50 specialists, mostly from BP, centers more on how rig workers, mostly from Transocean, responded after the blowout, and less on BP's choices in designing and drilling the well.
In a press release accompanying the report, BP CEO Tony Hayward said:
To put it simply, there was a bad cement job and a failure of the shoe track barrier at the bottom of the well, which let hydrocarbons from the reservoir into the production casing ...
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.
One of the most telling findings from the report, if true, is that the blowout came up the center of the pipe, and not outside of the well casing. That would help dispel the idea that BP, the author of the report, is guilty of gross negligence for using cheaper casing, even though they knew it was risky, and opting to use fewer centralizers than had been advised, endangering the casing's position.
The Department of Justice is unlikely to give the report much credence as it weighs the decision to pursue criminal or civil charges. But the Times calls the findings "a first glimpse at BP’s probable legal strategy in defending itself."