A new report on the April 2010 Gulf of Mexico oil-well blowout concludes that industry and regulators had a “misplaced trust” in the blowout preventer used by the Deepwater Horizon rig.

Like many other reports about the Gulf Coast disaster, the National Academy of Engineering/National Research Council study, released on Dec. 14, concludes that the accident, which killed 11 rig workers and spewed more than four million barrels of oil into the Gulf, was caused by a combination of factors.

But the National Academy report includes additional insight and recommendations on necessary improvements to blowout preventer (BOP) systems.

The study team said that BOP systems commonly in use are neither designed nor tested to operate in the type of conditions that occurred on the night of the accident.

The panel chairman, University of Michigan Professor Donald Winter, said, “As a result, the committee has recommended that BOP systems should be redesigned to provide robust and reliable cutting, sealing and separation capabilities commensurate with the conditions that may be present in an emergent situation.”

Such a redesign will take time, the study authors noted. In the meantime, industry should ensure timely access to demonstrated capping and containment systems that can be rapidly deployed during a future blowout, they said.

Perhaps the most significant factor in the accident, the study authors concluded, was the decision to abandon the Macondo well temporarily despite the results of multiple negative pressure tests. Those tests showed that the cement put in place had not formed an effective seal or barrier to isolate hydrocarbons from the well bore.