The failure inside the blowout preventer, and in the Obama administration
...There is much more. This is a long story covering nine internet pages. It is an investigative report that sheds light instead of the heat we saw recently in Congress.
Its very name — the blind shear ram — suggested its blunt purpose. When all else failed, if the crew of the Deepwater Horizon oil rig lost control of a well, if a dreaded blowout came, the blind shear ram’s two tough blades were poised to slice through the drill pipe, seal the well and save the day. Everything else could go wrong, just so long as “the pinchers” went right. All it took was one mighty stroke.
On the night of April 20, minutes after an enormous blowout ripped through the Deepwater Horizon, the rig’s desperate crew pinned all hope on this last line of defense.
But the line did not hold.
Engineers sent robotic submersibles 5,000 feet deep to prod the blind shear ram, nestled in the bosom of a five-story blowout preventer standing guard over the Macondo well.
They were driven on, documents and interviews reveal, by indications that the shear ram’s blades had come within a few maddening inches of achieving their purpose. Again and again, they tried to make the blades close completely, knowing it was their best chance to end the nightmare of oil and gas billowing into the Gulf of Mexico.
“If that would’ve worked,” a senior oil industry executive said of the blind shear ram, “that rig wouldn’t have burned up and sunk.”
Engineers contended with hydraulic fluid leaks that may have deprived the ram of crucial cutting force. They struggled to comprehend what was going on in the steel sarcophagus that encased the shear ram, as if trying to perform surgery blindfolded.
They wondered if the blades had by chance closed uselessly on one of the nearly indestructible joints that connect drilling pipe — a significant bit of misfortune, given a decision years before to outfit the Deepwater Horizon’s blowout preventer with just one blind shear ram when other rigs were already beginning to use two of them to guard against just this possibility.
An examination by The New York Times highlights the chasm between the oil industry’s assertions about the reliability of its blowout preventers and a more complex reality. It reveals that the federal agency charged with regulating offshore drilling, the Minerals Management Service, repeatedly declined to act on advice from its own experts on how it could minimize the risk of a blind shear ram failure.
It also shows that the Obama administration failed to grapple with either the well-known weaknesses of blowout preventers or the sufficiency of the nation’s drilling regulations even as it made plans this spring to expand offshore oil exploration.
As it turns out, records and interviews show, blind shear rams can be surprisingly vulnerable. There are many ways for them to fail, some unavoidable, some exacerbated by the stunning water depths at which oil companies have begun to explore.
But they also can be rendered powerless by the failure of a single part, a point underscored in a confidential report that scrutinized the reliability of the Deepwater Horizon’s blowout preventer. The report, from 2000, concluded that the greatest vulnerability by far on the entire blowout preventer was one of the small shuttle valves leading to the blind shear ram. If this valve jammed or leaked, the report warned, the ram’s blades would not budge.
This sort of “single-point failure” figures prominently in an emerging theory of what went wrong with the Deepwater Horizon’s blind shear ram, according to interviews and documents. Some evidence suggests that when the crew activated the blind shear ram, its blades tried to cut the drill pipe, but then failed to finish the job because one or more of its shuttle valves leaked hydraulic fluid.
The newer blowout preventers have a second blind shear ram providing the redundancy that was needed in this case. That maybe the most important finding when all the investigations are done. I suspect in the new regulations that will be written two blind shear rams will be required on all blowout preventers. When you consider the costs of this disaster, that is a relatively cheap fix.