HOUSTON – A draft assessment of the Macondo blowout by the US Chemical Safety Board concludes that the BOP failed to seal the well because the drill pipe buckled.
The buckled pipe moved off center within the BOP, which precluded the successful ram function, earlier in the timeline than previously estimated. The CSB also concludes that the BOP’s blind shear ram did activate the night of the accident, days earlier than estimated in other assessments. The report says that “effective compression” of the drill pipe caused the ram to puncture the off-center pipe.
“Our investigation has produced several important findings that were not identified in earlier examinations of the blowout preventer failure,” said CSB Investigator Cheryl MacKenzie, who led the investigative team.
“Although there have been regulatory improvements since the accident, the effective management of safety critical elements has yet to be established. This results in potential safety gaps in US offshore operations and leaves open the possibility of another similar catastrophic accident.”
“The CSB’s conclusions are based on real-time pressure data from the Deepwater Horizon and calculations about the behavior of the drill pipe under extreme conditions,” said Dr. Mary Beth Mulcahy, who oversaw the technical analysis. “The findings reveal that pipe buckling could occur even when a well is shut-in and apparently in a safe and stable condition. The pipe buckling – unlikely to be detected by the drilling crew – could render the BOP inoperable in an emergency.”
The CSB also says it found several miswirings and battery failures within the BOP subsea controls that contributed to the failure.
Two forthcoming volumes of the CSB’s Macondo investigation report are planned to address additional regulatory matters as well as organizational and human factors safety issues raised by the accident.
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