Panel: Redesign Blowout Preventers

Friday, December 16, 2011 @ 04:12 PM gHale


There was a “misplaced trust” in the ability of blowout preventers to act as fail-safe mechanisms, a new report said.

Blowout preventers, which should seal off an oil well in an emergency, must undergo a redesign to prevent failures like the one last year at BP Plc’s Macondo well in the Gulf of Mexico, said a committee of the National Academy of Engineering and National Research Council in the report.

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The 57 foot (17 meter) valve systems, which stand atop deep-water wells, were not tested for the conditions that existed when the Macondo well exploded, the report found.

A blowout at the Macondo well in April 2010 killed 11 workers aboard Transocean Ltd.’s Deepwater Horizon drilling rig off the coast of Louisiana, causing it to sink and resulting in the biggest offshore U.S. oil spill in history. An estimated 4.9 million barrels of crude went into the Gulf while operators fought for 87 days to seal the well.

If the blowout preventer had cut off the flow of oil and gas from the well, the rig might not have sunk and the spill probably would’ve been smaller, the report found.

“It failed to stop the blowout because of its design and operational shortcomings,” the committee reported. “There is an urgent need for those shortcomings to be corrected.”

The 400-ton system built by Cameron International Corp. was four years overdue for maintenance and hadn’t been disassembled and refurbished since they commissioned the Deepwater Horizon in 2001, said Jason Mathews, a member of a joint U.S. Coast Guard-Interior Department investigative panel, during an April 6 hearing in Metairie, LA.

Cameron invented blowout preventers in 1922 and “the evolution of this expensive and long-lived piece of equipment appears to have been limited,” according to today’s report. It “was neither designed nor tested for the dynamic conditions that most likely existed at the time that attempts were made to recapture well control” at Macondo.

There’s no industry standard or independent certification for blowout preventers as there is for household circuit breakers, another safety device designed to prevent fires, said Roger McCarthy, a panel member and engineer based in Palo Alto, CA.

There needs to be more rigor to understand the potential demands on a subsea blowout preventer, said Donald Winter, the committee chairman. Engineers need to build in better instrumentation so operators can identify what’s going on at the wellhead, he said.

“It’s not a matter that’s going to be accomplished in a very short period of time,” Winter said.

The report, requested by Interior Secretary Ken Salazar, is the latest in a series of three government probes of the disaster. President Barack Obama appointed a commission to investigate the spill and the Coast Guard and Interior Department held their own joint inquiry.

A November 2010 interim report by the same committee issuing today’s findings said key staff overlooked signs of a failed cement plug that led to the blowout. It accused BP, its contractors and federal regulators of weak oversight. This week’s report proposes new procedures and regulation of well design and offshore rigs.

The report also calls for redesign of blowout preventers to allow for “robust and reliable cutting, sealing and separation,” as well as new testing and maintenance procedures.

The government in September 2010 required drillers to have third-party verification that blowout preventers are capable of cutting off pipes, as well as having the ability to remotely close off the valves.

The report “has helped to affirm the tremendous efforts we have made in the last 18 months to raise the bar for safety and oversight of offshore oil and gas operations,” Salazar said. “The work we have done to implement rigorous new offshore drilling and safety rules and reform offshore regulation and oversight is in line with the recommendations of the committee.”



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