The internal BP report detailing the series of failures that led to the Deepwater Horizon explosion and Gulf oil spill was released on the company's website on Wednesday.

The 193-page report concludes that decisions made by “multiple companies and work teams” 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.” It delineates eight specific safeguards that should have averted the fire and spill — all failed or were ignored due to human error. The report places blame on both BP employees and protocol while shifting large amounts of responsibility onto contractors Halliburton and Transocean.

"This report is not BP's mea culpa," said Massachusetts Rep. Edward J. Markey, a member of a congressional panel investigating the spill. "Of their own eight key findings, they only explicitly take responsibility for half of one. BP is happy to slice up blame, as long as they get the smallest piece."

A chronological picture of the events of April 20 is still unfolding, but the failures included the proper cementing of the well, as well as the mechanical failures and human error that caused the BP crew to mistakenly believe the well was properly sealed.

Following the incorrect conclusion that the well was sealed properly, natural gas hydrocarbons entered the well chamber and rose past all safeguards into highly unsafe areas, including the engine room, where it eventually combusted. The report confirms that employees critically misinterpreted the pressure integrity test, not only allowing the leakage to continue uninterrupted but performing other tasks that exacerbated the problem. With proper well monitoring or well control responses, this issue could have been rectified, but employees were slow to notice issues and by the time corrective measures were taken, they were too late and insufficient.

Moreover, once the gas ignited on the Deepwater Horizon, equipment to contain it failed or was already bypassed.

Finally, the blowout preventer failed due to the explosion, preventing an employee-initiated attempt, and the self-sealing measures (set to be automatically activated under well failure) did not occur in part because the batteries controlling it were dead. Or, in BP-speak, they "had insufficient charge ... at the time of the accident."

Transocean's name appears more than 75 times in the report, and Halliburton is referenced more than 100 times. One contractor whose name is nowhere to be found? Schlumberger.

The report gives no reference to the fact that a Schlumberger crew was on board the Deepwater Horizon mere hours before the explosion and were hurriedly whisked away before completing the Cement Bond Log test to ensure the integrity of the well. Reports have surfaced that conditions on the rig caused the Schlumberger crew to exit early via a helicopter sent by the company, though a Schlumberger spokesman has said the crew departed on a regularly-scheduled BP helicopter.

The BP report says upfront that the errors and failures were not presented with an eye to legal liability standards, though certain absences and name omissions speak volumes. Though the report makes numerous references to employee error, it never references who was making the decisions to ignore data that indicated problems, or who was responsible for maintenance or monitoring of equipment that was compromised.

"Basically, what BP is trying to do is come up with both a legal and a (public relations) explanation," NPR Science Correspondent Richard Harris said. "A lot depends on whether (BP) was grossly negligent or whether this was a whole series of accidents."