WASHINGTON — A piece of drill pipe knocked askew as BP’s Macondo well surged out of control kept its blowout preventer from averting last year’s disastrous oil spill in the Gulf of Mexico, according to an investigation released Wednesday.
In the first comprehensive analysis of why the supposedly fail-safe equipment didn’t work as planned, investigators concluded that powerful blind shear rams on the device were unable to completely slash through slightly off-center drill pipe, seal the well hole and trap oil and gas underground.
The chief problem was that as soon as oil and gas surged out of the deep-sea well, drill pipe buckled and shifted to one side — partly outside the path of the cutting rams.
“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,” said the 551-page report by forensic analysis firm Det Norske Veritas.
The company determined the failure would have occurred regardless of how the blowout preventer, or BOP, was activated.
The shears were designed to be closed by hydraulic signals sent by the crew of the Deepwater Horizon drilling rig on the Gulf surface a mile above, or by an automatic “deadman’s switch” activated if the blowout preventer lost communication with the rig.
An explosion after the blowout destroyed the Deepwater Horizon and killed 11 workers.
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. They are set to convene hearings on the BOP report the week of April 4 in New Orleans.
The report adds to other conclusions about the oil spill, including a presidential commission’s determination that the blowout was the culmination of a series of decisions that increased risk at the site.
Invented nearly 90 years ago, BOPs are giant stacks of valves installed on top of land and sea wells to help maintain control during unexpected pressure changes.
As a last line of defense against runaway wells, BOPs have been compared to air bags and seat belts that don’t prevent auto crashes but can reduce injuries.
The report cast fresh doubt on the effectiveness of BOPS and renewed calls for a redesign of the devices, including proposals for redundant pipe-cutting components and more powerful rams.
Do they work at all?
“It isn’t clear from this report that blowout preventers can actually prevent major blowouts once they’ve started,” said Rep. Ed Markey, D-Mass., the top Democrat on the House Natural Resources Committee.
DNV, the forensic firm, recommended the oil industry further study whether shear rams can “complete their intended function” and completely cut drill pipe, no matter where it is in the well hole. It said that those conclusions should be incorporated in the design of future blowout preventers and used to modify those already deployed.
After last year’s spill, lawmakers and some Obama administration officials signaled their wariness about the industry’s reliance on BOPs that are manufactured by just a few companies, including Cameron International, the industry leader; National Oil Well Varco; and GE-owned Hydril Pressure Control.
“The BOPs are manufactured by a very small number of companies,” Interior Secretary Ken Salazar said last July. “And BOPs used across the industry tend to employ standardized components.”
A spokesman for Houston-based Cameron, which manufactured the Macondo well’s BOP, noted that it “was designed and tested to industry standards and customer specifications,” and said the company continued “to work with the industry to ensure safe operations.”
Transocean, which owned and operated the Deepwater Horizon, said that the examination confirms the BOP “was in proper operating condition and functioned as designed.” The company added: “High-pressure flow from the well created conditions that exceeded the scope of BOP’s design parameters.”
Concern that Wednesday’s report could boost liability sent Cameron’s stock down nearly 2 percent in trading, to close at $58.82 a share.
But Jeff Spittel, an analyst with the Houston investment banking firm Madison Williams, said he doesn’t believe the BOP findings will shift legal liability for the accident onto Cameron, because Transocean owned and operated the device.
And an indemnification clause in Transocean’s contract with BP could shield it from responsibility.
Satish Nagarajaiah, a civil engineering professor at Rice University, said DNV’s report affirms that a “complete shut-off of the well would have been possible,” if the blind shear rams had been activated when the pipe was still centered.
The shear rams worked once they were activated, he said, but failed to stop the blowout because “the circumstances under which they performed were so abnormal and so difficult.”
Officials for BP, which leased the Deepwater Horizon drilling rig from Transocean, said the oil company agreed with DNV’s “recommendation that additional testing should be completed to provide a more comprehensive view of why the BOP failed.”
Dlouhy reported from Washington and Fowler from Houston