HOUSTON – Four years after the worst offshore oil spill in U.S. history, federal investigators shed new light Thursday on why a key safety device failed to stop a blowout at BP’s Macondo well.
In a two-volume draft report, the Chemical Safety Board said the problem started when an unexpected burst of pressure from the reservoir, called a kick, occurred around 8:45 p.m. on April 20, 2010. A long drill pipe running from the rig down into the ocean floor buckled under the high pressure coming up from the oil reservoir. The drill pipe bent and curved, making it impossible for a final fail-safe system in the safety device, called a blowout preventer, to cut the pipe and seal the Macondo well.
The blowout caused an explosion on Transocean Ltd.’s Deepwater Horizon killing 11 workers and causing oil to gush into the Gulf of Mexico for 87 days. The rig lost power and burned for two days before it sank into the ocean.
The CSB, which typically examines the root causes of accidents at refineries and chemical plants, said the pressure behind the buckling drill pipe is a danger that neither regulators or the industry have considered before, leaving other rigs vulnerable as the threat of faulty blowout preventers remains undetected. The agency said it had access to data on the blowout preventer that other federal probes into the disaster did not, enabling it to form new conclusions about what went wrong with the device.
The CSB concluded that U.S. regulations governing offshore safety — even new rules set after the 2010 oil spill — do not address many key safety devices. U.S. regulators could, like other governments, beef up those protocols, the CSB concluded.
“What these technical findings and conclusions mean for industry is that the buckling of the drill pipe can actually occur when the well is successfully shut in by the drill crew, and remain undetected,” said Cheryl MacKenzie, team lead investigator on the Deepwater Horizon incident for CSB, during a press conference in downtown Houston on Thursday. “Similar deficiencies identified in the Deepwater Horizon BOP could remain undetected in BOPs today.”
The agency said it conducted interviews and collected nearly 1 million documents from 24 companies and other entities.
Conclusions in the report are not considered final and are only to help determine the agency’s potential recommendations to the Bureau of Safety and Environmental Enforcement and the American Petroleum Institute, two key bodies that oversee and influence the U.S. offshore industry.
Miswirings and battery failures
The findings could also overturn the prevailing theory that the two sharp blades within the blowout preventer, designed to seal a well in an emergency, were not activated until two days after the accident. The blades, known as “blind shear rams,” likely were activated on the night of the spill, said Mary Beth Mulcahy, an investigator for the CSB.
A miswiring disabled the blowout preventer’s control system, which was designed to activate the shear ram in an emergency. A separate miswiring caused another battery failure on an identical, redundant control system, but the two battery failures “canceled each other out.” That second battery failure triggered a shearing blade inside the blowout preventer, which attempted to cut the pipe. But it was unsuccessful because the drill pipe had been bent.
In the report, the CSB said the blowout preventer had been miswired before it was ever set on the sea floor, paralyzing certain key functions. Houston-based Cameron International manufactured the device and Swiss rig contractor Transocean owned it.
“Neither Transocean nor BP treated the Deepwater Horizon blowout preventer as a safety critical element,” the agency said in a written statement accompanying the report. “The component of the DWH blowout preventer meant to shear and seal the well was not suitable for the Macondo drilling operation, as it could not reliably shear the drill pipe.”
The CSB’s new findings show that as reservoir pressure climbed in the drill pipe, a mechanism called effective compression – pressure that can create curves in drill pipe that are invisible to the naked eye – elongated part of the pipe and bent it out of shape. The pipe fell off center inside the blowout preventer, and could not be cut by shear ram blades that would.
The Deepwater Horizon crew had managed to shut in the well with a pipe ram and prevent oil and gas from climbing up the riser, but not before the substances had escaped and eventually ignited at the rig. The drill pipe burst sometime after the last safety mechanism in the blowout preventer failed.
BP spokesman Geoff Morrell said CSB’s theory that the automatic emergency system worked despite the blowout preventer’s maintenance deficiencies “is based on flawed assumptions.”
“These theories ignore the physical evidence and testing performed during the BOP’s forensic examination and are contrary to the conclusions reached by other investigations,” he said. “Moreover, no party other than Transocean has ever concluded that the (emergency safety systems) worked despite the maintenance deficiencies.”
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The report comes amid legal challenges from Transocean, which had fought court battles to prevent certain data from getting into the agency’s hands. A federal judge in Houston ordered the rig contractor to hand over certain documents last year.
A federal judge in New Orleans could rule at any time on several factors that could determine how much BP owes in environmental fines, up to $18 billion. The London-based oil company has already set aside $42.7 billion to pay for oil spill costs.
Morrell said in an emailed statement the agency found “the Deepwater Horizon accident was the result of multiple causes, involving multiple parties, including Transocean.”
“Transocean, which owned the rig’s blowout preventer and was responsible for its maintenance, failed to, among other things, properly maintain the BOP and control the well,” Morrell said.
Transocean spokesman Brian Kennedy said the CSB report confirms the blowout preventer had been tested properly and had activated during the accident, “but was unable to seal the well because immense pressure buckled the drill pipe and prevented the blind shear ram from functioning as designed.”
“We respectfully disagree with other findings in the report, including and especially the CSB’s assertions regarding Transocean’s operational and safety culture,” he said.
‘Omits significant facts’
Other agencies and federal bodies, including a specially appointed commission, the Department of Interior and the U.S. Coast Guard, had investigated the oil spill more than a dozen times before the CSB’s report.
“There is nothing here that hasn’t already been exhaustively addressed by regulators and the industry,” said Brian Straessle, a spokesman for the American Petroleum Institute. “The report appears to omit significant facts and ignores the tremendous strides made to enhance the safety of offshore operations. Offshore drilling is safer today because industry and the government have enhanced spill prevention, containment and response, implemented new standards and rules, and focused on strong safety culture.”
The report also follows new regulations that require weekly testing of blowout preventers. But CSB says some tests could mask deficiencies in individual components because they rely heavily on redundant systems.
David Smith, a spokesman for the BSEE, said after the oil spill, the Obama Administration launched ” the most aggressive and comprehensive reforms to offshore oil and gas regulation and oversight in U.S. history” in an effort to bolster requirements from well design to workplace safety and corporate accountability.
The new set of rules “supports standards that emphasize a culture of safety, the development of oil spill response plans, enforcement of approved leases, plans and permits, and investments in the latest scientific research to enhance safety, reduce risk and keep pace with industry technologies,” Smith said.
In testing emergency safety systems within blowout preventers, the CSB noted that the many fail-safe systems masked failures of individual components of the device’s control systems. But testing those parts are not currently required by regulators, and similar deficiencies could be found in blowout preventers currently deployed to well heads.
Before the spill, regulators did not require operators to test emergency safety systems known as AFM/deadman systems, which activated the ram shear blades within the blowout preventer before the oil spill in 2010. The agency said it found deficiencies in those systems that escape even new required tests and that could affect units currently deployed.
Future volumes of the CSB’s report will look at the role of the U.S. regulator in the offshore industry, comparing it to other regulatory regimes across the globe, the agency said.
Michael Bromwich, former director of the BSEE, said the report comes after a number of earlier accounts “that served as the basis for meaningful regulatory and organizational reform in real time.”
“The (CSB) report finds a niche by focusing in great detail on the deficiencies of blowout preventers and on improvements that can be made in the government’s performance-based safety regulations,” he said. “If this focus stimulates continuing discussion on these issues, the report will have served a useful purpose.”