Report outlines eight reasons for the tragedy
No single factor caused the Deepwater Horizon oil tragedy. Rather, a sequence of failures involving a number of different parties led to the explosion and fire which killed 11 people and caused widespread pollution in the Gulf of Mexico earlier this year.
That is the main finding of a report by BP into the cause of the Gulf oil spill disaster
BP's internal inquiry spreads the blame across “multiple companies and work teams” (including BP, Halliburton and Transocean) who contributed to the accident which it says arose from “a complex and interlinked series of mechanical failures, human judgments, engineering design, operational implementation and team interfaces.”
Led by Mark Bly, BP’s Head of Safety and Operations the investigation uncovered eight reasons for the explosion and disaster that ensued.
The cement and shoe track barriers – and in particular the cement slurry that was used – at the bottom of the Macondo well failed to contain hydrocarbons within the reservoir, as they were designed to do, and allowed gas and liquids to flow up the production casing;
The results of the negative pressure test were incorrectly accepted by BP and Transocean, although well integrity had not been established;
Over a 40-minute period, the Transocean rig crew failed to recognise and act on the influx of hydrocarbons into the well until the hydrocarbons were in the riser and rapidly flowing to the surface;
After the well-flow reached the rig it was routed to a mud-gas separator, causing gas to be vented directly on to 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;
Even after the explosion and fire had disabled its crew-operated controls, the rig’s blow-out preventer on the sea-bed should have activated automatically to seal the well. But it failed to operate, probably because critical components were not working.
BP’s outgoing chief executive Tony Hayward said: “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. The negative pressure test was accepted when it should not have been, there were failures in well control procedures and in the blow-out preventer; and the rig’s fire and gas system did not prevent ignition.”
“We have said from the beginning that the explosion on the Deepwater Horizon was a shared responsibility among many entities,” BP’s incoming chief executive Bob Dudley said. “This was a tragic accident that resulted in the loss of 11 lives and impacted the communities and the environment along the Gulf Coast region. We deeply regret this event.”
The investigation team proposed a total of 25 recommendations designed to prevent a recurrence of such an accident.