U.S. Chemical Safety Board (CSB) has reported that 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, failed to seal the well because drill pipe buckled.
The blowout caused explosions and a fire on the Deepwater Horizon rig, leading to the deaths of 11 personnel onboard and serious injuries to 17 others. Nearly 100 others escaped from the burning rig, which sank two days later, leaving the Macondo well spewing oil and gas into Gulf waters for a total of 87 days. By that time the resulting oil spill was the largest in offshore history. The failure of the BOP directly led to the oil spill and contributed to the severity of the incident on the rig.
The CSB report concluded that the pipe buckling likely occurred during the first minutes of the blowout, as crews desperately sought to regain control of oil and gas surging up from the Macondo well. Although other investigations had previously noted that the Macondo drill pipe was found in a bent or buckled state, this was assumed to have occurred days later, after the blowout was well underway.
After testing individual components of the blowout preventer (BOP) and analyzing all the data from post-accident examinations, the CSB draft report concluded 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 did activate on the night of the accident, days earlier than other investigations found. 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.
Copyright, CSB.gov, 2014.