Report cites Transocean and Halliburton for key failures on doomed rig.
BP has released a controversial report outlining what the company believes led to the deadly explosion and collapse of the Deepwater Horizon Rig.
The BP analysis indicates a series of events, not a single factor, that caused the disaster.
The report also says no single company is responsible for the tragedy.
It cites eight key failures that led to the explosion and collapse of the well.
Most of those, according to the report, were the responsibility of rig operator Transocean or Halliburton, the company that cemented the well.
The BP analysis continues to defend the single casing well design of the rig, use of fewer centralizers during cementing, just six instead of the 21 recommended by Halliburton, and the decision to replace heavy drilling mud with water.
All of those were moves Congressional leaders have labeled as cost saving measures that led to the disaster.
A written response from Transocean touches on those factors and calls the bp investigation 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."
The report does acknowledge that BP personnel on the rig accepted faulty well integrity tests and failed to recognize increasing pressure and an influx of hydrocarbons in the riser until it was too late.
The most important investigation into the incident is still on-going.
Federal agents are examining the failed blowout preventer recently pulled from the floor of the gulf as the Justice Department looks into fines and possible criminal charges in the case.