WASHINGTON — An internal investigation released by BP on Wednesday concluded that a series of mechanical and human failures by its own crews and its contractors led to the explosion on the Deepwater Horizon drilling rig, which killed 11 men and set in motion one of the world's worst oil spills.
The oil company accepted a share of the responsibility but also took aim at contractors Transocean and Halliburton, setting off another round of finger-pointing that began soon after the rig sank.
No single factor caused the disaster, concludes the 234-page report summarizing the first of several investigations into the disaster. "A complex and interlinked series of mechanical failures, human judgments, engineering design, operational implementation and team interfaces came together to allow the initiation and escalation of the accident."
BP's investigative team cited eight problems, including an incorrectly read pressure test, a blowout preventer that didn't function properly, a faulty cement seal job and the failure of the rig crew to recognize that gas was surging up the well just before the explosion.
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"We have said from the beginning that the explosion on the Deepwater Horizon was a shared responsibility among many entities," BP's incoming CEO Bob Dudley said in a statement.
"We deeply regret this event," he added. "We are determined to learn the lessons for the future and we will be undertaking a broad-scale review to further improve the safety of our operations. We will invest whatever it takes to achieve that."
Transocean, the drilling rig owner, assailed the BP report as "self-serving," contending that BP's "fatally flawed well design" set the stage for the rig explosion 50 miles off the Louisiana coast.
Halliburton, which did the well cementing, said it found a "number of substantial omissions and inaccuracies" in the report and "remains confident that all the work it performed ... was completed in accordance with BP's specifications."
Based on a four-month investigation led by company safety chief Mark Bly, the BP document wraps up the first of a series of reviews looking into the gulf catastrophe.