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CSB initial report into Macondo incident highlights problems with blowout preventer

06 June 2014

The first part of the US Chemical Safety and Hazard Investigation Board (CSB) report into the April 2010 Gulf of Mexico disaster, published on June 5, concludes that problems with the Macondo well’s blowout preventer (BOP) were a direct cause of the incident. The blowout killed 11 members of the crew on the BP-leased Deepwater Horizon drilling platform and led to an 87-day long oil spill, the biggest in US history. 

The CSB report differs from some others in that it concludes the buckling of the drill pipe likely occurred during the first minutes of the blowout and that the BOP’s blind shear ram attempted to cut the pipe, but the pipe buckling prevented the shear ram from cleanly cutting and sealing the pipe.

“The shear ram actually punctured the buckled, off-center pipe, sending huge additional volumes of oil and gas surging toward the surface,” the report says.  Some of the other investigations concluded the blind shear ram did not activate at all.

Other flaws included two separate instances of bad wiring which contributed to the failure of two backup batteries on the pods designed to make sure the blowout preventer’s blind shear rams activated. This was blamed on faulty maintenance by Transocean, owner of the Deepwater Horizon.

The CSB is an independent federal agency charged with investigating industrial and chemical accidents and it hired outside consultants to assist in the Deepwater Horizon case. The board has struggled against other agencies during the BP oil spill investigation to gain access to damaged equipment, and it went to federal court to get its subpoenas enforced. It does not issue citations or fines but makes safety recommendations.

The CSB said it relied on information from a variety of sources, including relatively recent court cases, and some information, including a full set of BOP testing data, that was not available to the compilers of previous reports on the incident.

The board spread the blame across a number of the companies involved. Halliburton was responsible for a failure of the cementing job to temporarily seal the well, while the BOP made by Cameron International lacked the capacity to reliably cut and seal the drill pipe, even if the pipe had not buckled and had been properly centred.

The CSB also said that Transocean and BP failed to perform regular inspections of emergency systems.

Transocean has refused to cooperate with the board, saying the agency lacks jurisdiction. The agency filed suit, and a federal judge ordered Transocean to respond to its subpoenas for documents and interviews. Transocean has appealed.

The report says that in certain circumstances the buckling of the drill pipe could impact any offshore operator, even those who maintain their blowout preventers and other equipment to a high standard. CSB investigators identified the type of pipe buckling involved at the Macondo wellhead as “effective compression”, and concluded there were straightforward methods to avoid this type of buckling if it is recognised as a hazard.

BP, which said it fully cooperated with the board, said that the agency’s “core findings” were “consistent with the conclusion of every other official investigation: that the Deepwater Horizon accident was the result of multiple causes, involving multiple parties, including Transocean.”

But BP spokesman Geoff Morrell took issue with part of the report, which he said was “based on flawed assumptions” that the so-called deadman device to activate the blowout preventer had worked notwithstanding the “maintenance deficiencies.”

The report makes numerous recommendations to the US Department of Interior’s Bureau of Safety and Environmental Enforcement (BSEE), the US federal organisation established following the Macondo accident to oversee offshore safety.

These recommendations call on BSEE to require drilling operators to effectively manage technical, operational, and organisational safety-critical elements to help reduce major-accident risk to an acceptably low level.

The report also proposes the American Petroleum Institute revise API Standard 53, Blowout Prevention Equipment Systems for Drilling Wells, and provide new guidance for management of safety-critical elements in general.

The American Petroleum Institute said in a statement: “There is nothing here that hasn’t already been exhaustively addressed by regulators and the industry. The report appears to omit significant facts and ignores the tremendous strides made to enhance the safety of offshore operations.”

CSB chairman Rafael Moure-Eraso said:“Although both regulators and the industry itself have made significant progress since the 2010 calamity, more must be done to ensure the correct functioning of blowout preventers and other safety-critical elements.”

Two forthcoming volumes of the CSB’s Macondo investigation report are planned to address additional regulatory matters as well as organisational and human factors safety issues raised by the accident.

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