CSB Report Points to Blowout Preventer Failure in Deepwater Explosion

Photo by U.S. Coast Guard

The blowout preventer (BOP) that was intended to shut off the flow of high-pressure oil and gas from the Macondo well in the Gulf of Mexico during the disaster on the Deepwater Horizon drilling rig on April 20, 2010, failed to seal the well because drill pipe buckled for reasons the offshore drilling industry remains largely unaware of. That's a key finding discussed in a two-volume draft investigation report released today by the U.S. Chemical Safety Board (CSB).

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According to CSB, the BOP's failure directly led to the oil spill and contributed to the severity of the incident on the rig. The CSB will meet later today to consider the draft report for approval. A webcast of the meeting begins at 4 p.m. CDT today.

The CSB report concludes that the pipe buckling likely occurred during the first minutes of the blowout, as crews tried to regain control of oil and gas surging up from the well. The report indicates that the BOP’s blind shear ram – an emergency hydraulic device with two sharp cutting blades, intended to seal an out-of-control well – likely activated on the night of the disaster. However, the pipe buckling that likely occurred on the night of April 20 prevented the blind shear ram from functioning properly. Instead of cleanly cutting and sealing the well’s drill pipe, the shear ram actually punctured the buckled, off-center pipe, sending huge additional volumes of oil and gas surging toward the surface and initiating the 87-day-long oil and gas release into the Gulf that defied multiple efforts to bring it under control.

"The identification of the new buckling mechanism for the drill pipe ­– called 'effective compression'– was a central technical finding of the draft report," CSB states. "Under certain conditions, the 'effective compression' phenomenon could compromise the proper functioning of other blowout preventers still deployed around the world at offshore wells. The complete BOP failure scenario is detailed in an 11-minute computer video animation the CSB developed and released along with the draft report.

Learn more about the draft reports on the CSB website.