BP shares responsibility for Gulf oil spill in report

8 September 2010

It said a sequence of failures involving a number of different parties, rather than a single factor, led to the explosion and fire that killed 11 people and caused almost five million barrels of oil to flow into the sea earlier this year.

The report, based on a four-month investigation carried out by over 50 internal and external specialists, concluded that the accident arose from ‘a complex and interlinked series of mechanical failures, human judgments, engineering design, operational implementation and team interfaces.’

Failure of the cement barriers rather than the design of the well itself were found to be the initial cause of the oil leak, the report said, while the response of the rig crew and safety systems failed to control the effects of the accident.

BP’s outgoing chief executive Tony Hayward, who has been replaced following widespread criticism of his handling of the crisis, said: ‘Multiple parties, including BP, Halliburton and Transocean, were involved.

‘To put it simply, there was a bad cement job and a failure of the shoe track barrier at the bottom of the well, which let hydrocarbons from the reservoir into the production casing.

‘Based on the report, it would appear unlikely that the well design contributed to the incident, as the investigation found that the hydrocarbons flowed up the production casing through the bottom of the well.’

Once the cement was in place, a negative-pressure test was conducted to check the integrity of the barriers and the results were incorrectly accepted by BP and Transocean, even though well integrity had not been established.

Over a 40-minute period, the Transocean rig crew then failed to recognise and act on the influx of oil into the well until it was already flowing to the surface. Once the flow reached the rig it was routed to a mud-gas separator, causing gas to be vented directly onto the rig rather than being diverted overboard.

The flow of gas into the engine rooms through the ventilation system created a potential for ignition, which the rig’s fire and gas system did not prevent.

And once the explosion and fire had disabled the crew-operated controls, the rig’s blow-out preventer failed to seal the well automatically, probably because critical components were not working.

BP’s incoming chief executive officer Bob Dudley said: ‘We deeply regret this event. We have sought throughout to step up to our responsibilities.

‘We are determined to learn the lessons for the future and we will be undertaking a broad-scale review to further improve the safety of our operations. We will invest whatever it takes to achieve that.’

Based on its key findings, the investigation team has proposed a total of 25 recommendations designed to prevent a recurrence of such an accident.

These are directed at strengthening assurance on blow-out preventers, well control, pressure testing for well integrity, emergency systems, cement testing, rig audit and verification, and personnel competence.

The company said it expected a number of the investigation report’s findings to be considered relevant to the oil industry more generally and for some of the recommendations to be widely adopted.

BP’s chairman, Carl-Henric Svanberg, said: ‘I believe this report will be of significant value in helping the overall understanding of how this tragedy occurred.

‘It is of the utmost importance to the board to ensure that BP learns from this and further enhances the safety of its operations for the future.’

Transocean responded with a strongly worded statement. It said: ’This is a self-serving report that attempts to conceal the critical factor that set the stage for the Macondo incident: BP’s fatally flawed well design.

’In both its design and construction, BP made a series of cost-saving decisions that increased risk - in some cases, severely.’