Macondo report draws mixed response

A federal investigation of the Macondo disaster does not pinpoint what caused the well's cement job to fail, but backs up earlier conclusions that operator BP and its contractors skirted safety measures that could have prevented the blowout. Russell McCulley reports.

The long-delayed report from the Bureau of Ocean Energy Management, Regulation & Enforcement (BOEMRE) and US Coast Guard joint investigation team, eventually released 14 September, compiles information gathered by forensic examinations, testimony from more than 80 witnesses and experts, and documents relating to the 20 April 2010 blowout in the deepwater Gulf of Mexico. The explosions and fire aboard the Deepwater Horizon rig killed 11 and led to the worst offshore oil spill in US history.

The report includes findings released earlier this year covering aspects of the disaster under Coast Guard jurisdiction: the explosions and fire on the MODU, evacuations, the sinking of the Deepwater Horizon rig and the safety systems of its owner, Transocean.

The multi-volume document also delves into the causes of the Macondo well blowout in 5000ft water depths at Mississippi Canyon block 252, finding that ‘a number of federal offshore safety regulations' were violated by license operator BP, Transocean and Halliburton, which performed the well's failed cement job.

The final report stands by the results of a forensic investigation of the well's BOP, conducted by DNV, which determined that a buckled drill pipe prevented the blind shear ram from completely closing. But investigators could not reach a verdict on the precise cause of the casing cement job failure, instead listing a number of ‘likely' causes: the swapping of cement and drilling mud in the shoe track; contamination of the shoe track cement; or ‘over-displacement' from pumping the cement past the target location in the well.

While the report alleges safety lapses among all three companies involved, BP ‘was ultimately responsible for conducting operations at Macondo in a way that ensured the safety and protection of personnel, equipment, natural resources, and the environment,' investigators said.

‘The loss of life at the Macondo site on April 20, 2010, and the subsequent pollution of the Gulf of Mexico through the summer of 2010 were the result of poor risk management, last-minute changes to plans, failure to observe and respond to critical indicators, inadequate well control response, and insufficient emergency bridge response training by companies and individuals responsible for drilling at the Macondo well and for the operation of the Deepwater Horizon,' the report said.

BP released a statement acknowledging its role in the accident and calling on ‘other parties' to do the same.

‘BP agrees with the report's core conclusion – consistent with every other official investigation – that the Deepwater Horizon accident was the result of multiple causes, involving multiple parties, including Transocean and Halliburton,' the company said.

Transocean put out a statement taking issue with the investigation team's comments on the company's maintenance and safety practices aboard the rig.

‘The report confirms that the primary cause of the incident was the catastrophic failure of the cement in the Macondo well, and finally puts to rest all previous allegations that improper maintenance of the BOP contributed to the tragedy. As the report rightly concludes, the magnitude of the hydrocarbon release made the ignition and explosion onboard the Deepwater Horizon unavoidable,' Transocean said.

‘We take strong exception to criticisms of the Horizon drill crew, nine of whom perished fighting to save their fellow crewmembers and the rig, for the actions they took in the face of such an unprecedented emergency.'

Halliburton said the evidence presented in the report pointed to a failure of the well's shoe track cement, not the annular foam cement, and that the well completion was done in accordance with BP's ‘operational decisions'.

‘Such operational decisions included placing too light of a drilling mud in the rat hole, causing likely swapping with heavier shoe track cement; setting production casing in the vicinity of a hydrocarbon interval; ignoring industry standards by not properly conditioning or circulating the well prior to the cement job; and not drilling a larger hole diameter. The report further specifically states "the Panel concluded that the nitrified cement in the annulus likely did not fail",' Halliburton said in a statement obtained by OE.

‘The Bureau of Ocean Energy Management report incorrectly attributes the operation decisions to Halliburton. Every contributing cause where Halliburton is named, the operational responsibility lies solely with BP,' the statement said. OE