The report, released Wednesday, said in the days leading up to the disaster, BP made a series of decisions that complicated cementing operations, added risk, and may have contributed to the ultimate failure of the cement job.
The details were contained in the final report from an investigation team of the U.S. Coast Guard and the agency that regulates offshore drilling. The panel held hearings in the year following the April 20, 2010, Deepwater Horizon tragedy. The Coast Guard-Bureau of Ocean Energy Management Regulation and Enforcement investigation was among the most exhaustive.
Other investigations spread around the blame rather evenly, faulting misreadings of key data, the failure of the blowout preventer to stop the flow of oil to the sea and other shortcomings by executives, engineers and rig crew members. The joint investigation team laid considerable blame on BP's shoulders.
The report said the decisions included using only one cement barrier and BP's choice to set the production casing in a location in the Macondo well that created additional risk of influx of oil or gas. The casing is a steel pipe placed in a well to maintain its integrity.
The panel said BP failed to communicate these decisions and the increasing operational risks to rig owner Transocean.
"BP, as the designated operator under BOEMRE regulations, was ultimately responsible for conducting operations at Macondo in a way that ensured the safety and protection of personnel, equipment, natural resources, and the environment," the panel concluded.
In addition to the rig worker deaths, the resulting oil spill off Louisiana spewed more than 200 million gallons of crude from an undersea well owned by BP. The disaster caused billions of dollars in damages to hundreds of miles of coastline and wreaked havoc on the Gulf economy.
The report pins the causes for the disaster on many of the same faulty decisions as previous probes, including those by the president's independent oil spill commission, Congressional committees and the companies themselves. But it is likely to carry more weight in Congress, where Republican lawmakers in particular have said they are unwilling to adopt reforms until the federal investigation was complete.
Since the disaster, the Obama administration has reorganized the offshore drilling agency and boosted safety regulations. But Congress has yet to pass a single piece of legislation to address safety gaps highlighted by the disaster.