BP report spreads blame across Gulf spill actors

Faulty cementing, a misread pressure test and an improperly maintained blowout preventer all contributed to the April 20 explosion that uncorked the worst oil spill in U.S. history, BP's investigation of the disaster concluded Wednesday.

BP said its team aboard the doomed oil rig Deepwater Horizon "incorrectly accepted" results of a negative pressure test aboard the rig before the blast, but the company's internal report assigns much of the blame to rig owner Transocean and cementing contractor Halliburton. The three companies have repeatedly pointed fingers at each other since the explosion, which killed 11 workers and resulted in an estimated 4.9 million barrels (205 million gallons) of oil spilling into the Gulf.

"The team did not identify any single action or inaction that caused this accident," BP's report states. "Rather, a complex and interlinked series of mechanical failures, human judgments, engineering design, operational implementation and team interfaces came together to allow the initiation and escalation of the accident. Multiple companies, work teams and circumstances were involved over time."

BP acknowledged that its team leaders aboard the rig should not have accepted the results of a key test of the cement seal on the well shortly before the explosion. Those well site leaders -- the "company men" aboard the rig -- have refused to appear before a Coast Guard-Interior Department board investigating the disaster, with one invoking his Fifth Amendment rights against self-incrimination and the other citing illness.

"In retrospect, pressure readings and volume bled at the time of the negative-pressure test were indications of flow-path communication with the reservoir, signifying that the integrity of these barriers had not been achieved," the report states. "The Transocean rig crew and BP well site leaders reached the incorrect view that the test was successful and that well integrity had been established."

BP owned the Macondo well, located in about 5,000 feet of water about 45 miles off southeastern Louisiana, and hired Transocean and Halliburton as contractors. Wednesday's report found weaknesses in the design of the cementing job that allowed oil and gas to burst out of the well, and states that BP investigators found signs of "potential weaknesses in the testing regime and maintenance management system" for the rig's blowout preventer -- the massive fail-safe device that failed to shut down the well.

BP's investigation found Halliburton used a "likely unstable" cement mix that was not fully tested before it was used. Mark Bly, BP's head of safety and operations, said in a video accompanying the report, said Halliburton "did not conduct comprehensive lab tests that could've identified potential problems with the cement."

But he added, "We believe that BP and Halliburton working together should have better identified and addressed the issues underlying the cement job."

"Improved technical assurance, risk management, and management of change by BP personnel could have lead to awareness and better decisions regarding acceptance and implementation of the cement proposal," Bly said.

The conclusions follow July remarks by outgoing BP CEO Tony Hayward, who said that the disaster "was the result of multiple equipment errors and human error involving many companies." Bob Dudley, who is replacing Hayward, said Wednesday's report "makes that conclusion even clearer."

"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," Dudley said in a statement accompanying the report. "We will invest whatever it takes to achieve that. It will be incumbent on everyone at BP to embrace and implement the changes necessary to ensure that a tragedy like this can never happen again."

There was no immediate response to the report from either Halliburton or Transocean. But in testimony before the Coast Guard-Interior Department board, Halliburton engineer Jesse Gagliano said he warned BP that its well design was inadequate.

In addition, e-mails from BP engineers, released by a congressional committee in June, suggest that the oil company had its own concerns about the well. Drilling engineer Brian Morel called it a "nightmare well which has everyone all over the place," while Mark Hafle called it "a crazy well."

Hafle told the investigative board in May that BP was confident about the safeguards on its Gulf well. But BP reported problems controlling the well and won a delay in testing the blowout preventer in March, according to documents released by the House Energy and Commerce Committee. Committee leaders said the documents suggest BP took a cost-cutting and speedy approach to drilling the troubled well.

Both Hafle and Morel invoked their Fifth Amendment rights against self-incrimination during the most recent round of hearings by the investigative board.

Don Van Nieuwenhuise, an oil geoscience professor at the University of Houston, said the report points "a clear finger" at Halliburton in particular. But the report isolates several points at which someone should have said, "Hey, stop," as he put it.

Van Nieuwenhuise told CNN's "American Morning" that BP's representatives on the rig usually have "the ultimate decision," but added, "Someone from Transocean, if they suspect something is wrong, they certainly have the right to speak up and contradict the company man."

BP's report faults Transocean's crew for failing "to recognize and act on the influx of hydrocarbons into the well until the hydrocarbons were in the riser and rapidly flowing to the surface."

"Indications of influx with an increase in drill pipe pressure are discernable in real-time data from approximately 40 minutes before the rig crew took action to control the well," the report states. "The rig crew's first apparent well control actions occurred after hydrocarbons were rapidly flowing to the surface."

And the report states that service records for the blowout preventer and the condition of critical components "suggest the lack of a robust Transocean maintenance management system" for the device, which is meant to shut down the well in case of trouble.

(Published by CNN - September 8, 2010)