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With the anniversary of the Deepwater Horizon oil spill nearly upon us, research into the cause of the catastrophic chain of events, has yet to be fully disclosed. Tensions were running high once more last week, during the seventh round of a federal inquiry into the disaster, which took place in a suburb of New Orleans, Louisiana.

Focussing on the role of the blowout preventer (BOP), based on the results of a report by the Norwegian risk-management firm Det Norske Veritas (DNV), last week’s hearings before the federal investigative panel of the Coast Guard and the Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE) tried to shed some light on the happenings after the explosion, which unleashed the largest offshore oil spill in US history.

The BOP – did it fail or not?

Cameron International’s attorney David Jones, the company that manufactured the BOP for the Deepwater Horizon, asked the vice president and team leader of DNV’s investigation, Neil Thompson: "Dr Thompson, do you have any operational experience working on a drilling rig?" He answered: "I do not."

"Before your involvement in this investigations, had you laid eyes on a BOP?" Jones continued. And Thompson said: "I had not."

Even before the testimony began on Monday morning, 4 April 2011, Cameron International lawyers objected to the findings of DNV’s forensic reports, which examined the oil rig’s BOP, which had previously been recovered from the ocean floor. Thompson, however, testified that the device, consisting of valves, seals and hydraulic rams, did not work because after the force of the explosion, the drill pipe was not aligned just right.

Usually, when something goes wrong with a well, the BOP is supposed to clamp down, cut and seal the drill pipe, which was not the case after the Deepwater Horizon explosion, Thompson said. "The primary cause was that the drill pipe was off-centre in the well bore."

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By GlobalData

The BOP below the doomed oil rig had trouble triggering emergency disconnect functions when the rig lost control of the well. Nevertheless, the device actually offered more safety redundancies than other models, according to independent consultant Ralph Linenberger, who represented BP on a technical group advising forensic examiners.

Linenberger, who testified on Friday 8 April, before the panel, said the 2001 BOP model used by the Deepwater Horizon oil rig had double coils, both designed to fire to get emergency functions to activate. Control pods with electronic and hydraulic cables use batteries to disconnect from a rig in emergency situations whenever power and communications to a rig are lost.

DNV’s forensic examiners, however, had determined that the BOP’s two control pods had a dead battery and solenoid coils that did not always fire when tested after the accident.

Jason Mathews of BOEMRE, brought another interesting fact to light, when he said that the preventer used at the Deepwater Horizon oil rig was four years overdue for maintenance under Transocean‘s internal guidelines. The device had not been disassembled and refurbished since the rig was commissioned in 2001, which should have happened no later than the summer of 2006.

The US Interior Department is set to release be release its own report analysing the forensic report within the end of this week.

Transocean – ‘best year of safety’

Ahead of the hearing in Metaire, Deepwater Horizon rig owner Transocean, which lost nine workers in the blast, caused an outcry when officials described 2010 as its "best year for safety performance" and rewarded its directors with huge bonuses.

The company’s annual report, released the week before the seventh round of the federal inquiry, stated: "Notwithstanding the tragic loss of life in the Gulf of Mexico, we achieved an exemplary statistical safety record as measured by our total recordable incident rate and total potential severity rate."

"As measured by these standards, we recorded the best year in safety performance in our company’s history, which is a reflection on our commitment to achieving an incident-free environment, all the time, everywhere."

Following the statement, US politicians condemned the company for "insensitive wording" and forced the oil services company to officially apologise. Nevertheless, Transocean’s chief executive Steven L Newman received a $347,000 bonus and a base salary increase from $900,000 to $1.1m.

North Sea safety ultimatum

Only a few days later, however, Transocean was given a North Sea safety ultimatum by Health and Safety Executive (HSE) inspectors, who found that Transocean’s UK compulsory independent safety checks, known as verification schemes, are inaccurate and do not guarantee safety.

The HSE handed the company an improvement notice on 6 April, stating: "The current and proposed verification schemes for your installations operating in the United Kingdom Continental Shelf do not include an accurate list of safety-critical elements (SCEs) and do not ensure that safety-critical elements and specified plant are suitable."

SCEs include structures and equipment such as BOPs. Transocean, who has always maintained BP solely responsible for the oil spill, has now until 31 October to fulfil the notice – if not it will face further action from HSE.

Toll on human health still unknown

Meanwhile, a new review by professor at the Department of Environmental and Occupational Health at the University of Pittsburgh, published in the 7 April issue of the New England Journal of Medicine, suggested that the full magnitude of the environmental, economic and human health effects of the disaster may never be fully disclosed.

A large study, currently being conducted by the US National Institute of Environmental Health Sciences (NIEHS), could provide some answers but the fact that it was started six months after the incident happened, suggests that the initial levels of exposure to various chemicals have not been precisely recorded.

The 55,000 workers involved in the clean-up effort after the explosion could be left with unknown physical health consequences, caused by the chemicals dispersed in water, air and possibly also the food supply. According to the review, also mental health consequences have to be taken into account. The authors note that there have been more calls to mental health and domestic violence hotlines in the Gulf area since the oil spill.

One year after the disaster in the Gulf of Mexico, many factors that led to the biggest oil spill in history have yet to be discovered. Unlike the board meeting in Louisiana last week, the US presidential panel has already completed its investigation, blaming a series of time and money-saving decisions and management errors by Transocean, BP and Halliburton. The last word in the federal inquiry, however, will only fall in its final round in June 2011.