A piece of drill pipe wedged between key components of the blowout preventer used at BP’s doomed Macondo well kept the emergency equipment from blocking surging oil and gas — and stopping the Gulf spill last year — according to a forensic examination of the device.
The conclusions were outlined in a 551-page report released today and written by the forensic examination firm that has spent months putting the 60-foot-tall, 300-ton equipment through a battery of tests to find out why it failed April 20.
According to the firm, Det Norske Veritas, the failure was rooted in the inability of powerful blind shear rams on the device to slash through slightly off-center drill pipe and seal closed.
Because the portion of drill pipe located between the shearing blades of those rams had buckled and moved off-center, it was outside the space where the rams were designed to slash through obstacles.
“As the blind shear rams closed, a portion of the drill pipe cross section became trapped between the ram block faces, preventing the blocks from fully closing and sealing,” DNV reported.
The company elaborates:
As the blind shear rams were closed, the drill pipe was positioned such that the outside corner of the upper blind shear ram blade contacted the drill pipe slightly off center of the drill pipe cross section. A portion of the pipe cross section was outside of the intended blind shear ram shearing surfaces and would not have sheared as intended. As the blind shear rams closed, a portion of the drill pipe cross section became trapped between the ram block faces, preventing the blocks from fully closing and sealing.”
The company found that the physical problem would have occurred regardless of how the blowout preventer was activated — whether by an automatic “deadman’s switch” or using hydraulic signals sent from workers on the Deepwater Horizon rig that exploded and sank after the blowout.
The drill pipe probably shifted and buckled as soon as well control was lost, DNV found.
The report released today is likely to feed calls for a redesign of blowout preventers, including proposals for redundant pipe-cutting components and more powerful rams. On Capitol Hill, lawmakers have advanced legislation that would require an additional blind shear ram that could sever pipe and seal an open well hole even if debris blocked other rams from functioning.
The federal Bureau of Ocean Energy Management, Regulation and Enforcement separately imposed new mandates on blowout preventers, including independent third-party verification that the blind shear rams are capable of cutting any drill pipe in a well hole under the highest anticipated surface pressure.
Rep. Ed Markey, D-Mass., the top Democrat on the House Natural Resources Committee, said the report casts doubt on whether blowout preventers can ever be counted on as a last line of defense against runaway wells.
“Now we know there could also be systemic design issues with blowout preventers that could cause them to be ineffective, even when deployed as intended,” Markey said. “It isn’t clear from this report that blowout preventers can actually prevent major blowouts once they’ve started. We cannot turn a blind eye to the fact that the blind shear rams did not seem to work.”
Markey called on the Interior Department to immediately launch a top-to-bottom inspection of the design and effectiveness of blowout preventers used in U.S. waters.
Invented nearly 90 years ago, blowout preventers are giant stacks of valves installed on top of land and sea wells to help maintain control during unexpected pressure changes. The BOPs play their most vital role in emergencies, when metal shear rams are designed to slash through the drill pipe and casing, and a so-called blind shear ram is supposed to slam shut and seal off the open hole.
The blowout preventer at the Macondo well was manufactured by Cameron International and carried on Transocean’s Deepwater Horizon drilling rig.
A spokesman for Cameron noted that “the BOP was designed and tested to industry standards and customer specifications,” and said the company continued “to work with the industry to ensure safe operations.”
Officials for BP, which leased the Deepwater Horizon drilling rig from Transocean, said the oil company was still reviewing the report.
“We . . . agree with the report’s recommendation that additional testing should be completed to provide a more comprehensive view of why the BOP failed,” the company said in a statement. “We support efforts by regulators and the industry to make BOPs more reliable and effective.”
BP has asked a federal court to let the company put the equipment through more tests, but Cameron insists that any additional examination should be done by a neutral auditor. Officials with the Chemical Safety Board, which witnessed the BOP examination, also pushed for further testing.
DNV began testing the device at a NASA facility in New Orleans in mid-November, at the direction of the Coast Guard and Bureau of Ocean Energy Management, Regulation and Enforcement, which are jointly investigating the Deepwater Horizon disaster. The Coast Guard and ocean energy bureau will examine the blowout preventer testing results during hearings the week of April 4 in New Orleans.
All of the companies with a stake in the BOP testing — including BP, Cameron and Transocean — were on site for the examination, but they were barred from manipulating the device. Representatives from the Chemical Safety Board, the Justice Department and the plaintiffs in a spill class action lawsuit also were on hand for the testing.