The report from Transocean Ltd. said the April 20, 2010, Deepwater Horizon explosion and resulting oil spill was sparked by a succession of well design, construction, and temporary abandonment decisions that compromised the integrity of the well and compounded the risk of its failure. Transocean said many of the decisions were made by well owner BP in the two weeks before the incident.
The 854-page report doesn't say Transocean holds no blame for what caused the disaster, but it comes pretty close. In one of the few references to something Transocean workers didn't do correctly, the company report noted that none of the people monitoring the well, including the Transocean drill crew, initially detected the flow of oil through the well. However, the report said that once the crew did realize the well was flowing, it "undertook well-control activities that were consistent with its training." Transocean said the explosion was inevitable at that point.
Transocean said its evidence indicates that BP failed to properly assess, manage and communicate risk. On one key aspect - the failure of the blowout preventer to keep oil from leaking into the sea - Transocean seemed to suggest it takes no blame.
BP's own internal report on the disaster blamed a cascade of failures by multiple companies. Government investigations also have spread around the blame.
The findings by all sides will be argued about for months and perhaps years to come as numerous lawsuits make their way through court. The companies involved in the disaster have sued each other seeking to recoup losses or expected losses from the disaster. Fines ultimately imposed by the government could be in the billions of dollars, and the companies involved have been trying to shield themselves as much as possible.
The Transocean report said the findings don't represent the company's legal position, but they are consistent with many of the arguments the firm has been making for more than a year, and they are likely to be cited by Transocean in future proceedings.
BP officials did not respond to several requests for comment.
A key member of Congress and some Gulf residents reacted to the Transocean report with skepticism.
"I would look at it with a sense of suspicion, just from the simple fact that, obviously, there's a monetary gain or loss depending upon what they show their findings to be," said Chris Roberts, a Jefferson Parish, La., Council member whose jurisdiction includes the resort island community of Grand Isle.
As he headed to a demonstration at the Louisiana state capitol by a coalition of fishermen over the oil spill wrecking their livelihoods, Byron Encalade, president of Louisiana Oystermen's Association, said he thinks "there is a degree of responsibility on all parties."
In Washington, Rep. Edward Markey, a Massachusetts Democrat and ranking member of the House Committee on Natural Resources, called the Transocean report "the newest salvo in the continuing circular finger-pointing contest" by the companies involved.
In addition to owning the well that blew out, London-based BP was leasing the rig from Transocean. Eleven rig workers were killed and the government estimates some 206 million gallons of oil spewed from BP's Macondo well a mile beneath the sea before the well was capped three months later. It was the worst offshore oil spill in U.S. history, staining hundreds of miles of shoreline, hurting fishermen and businesses and prompting new rules for deepwater drilling. BP has already spent or committed tens of billions of dollars to clean up the mess and compensate victims.
The Transocean report was the culmination of work by an internal investigation team comprised of experts from various technical fields and other specialists. Transocean said the loss of evidence with the rig and the unavailability of certain witnesses limited its investigation and analysis in some areas.
Among Transocean's findings:
- BP did not properly communicate to the drill crew the lack of testing on the cement or the uncertainty surrounding critical tests and procedures used to confirm the integrity of the barriers intended to inhibit the flow of hydrocarbons from the well. A hydrocarbon is a compound consisting of hydrogen and carbon that is found in oil and gas.
- BP adopted a technically complex nitrogen foam cement program for sealing the well. The resulting cementing job was of minimal quantity, left little margin for error, and was not tested adequately before or after the cementing operation. Further, the integrity of the cement may have been compromised by contamination, instability, and an inadequate number of devices used to center the casing in the wellbore.
-Cement contractor Halliburton and BP did not adequately test the cement slurry used to seal the well.
-BP also failed to assess the risk of the temporary abandonment procedure used at Macondo. At the time of the explosion, BP was making sure the well was sealed so it could temporarily abandon the site and perhaps come back at some point in the future to produce oil from the exploratory well. Transocean said BP generated at least five different temporary abandonment plans for the Macondo well between April 12, 2010, and April 20, 2010. After this series of last-minute alterations, BP proceeded with a temporary abandonment plan that created risk and did not have the required government approval.
As for the 300-ton blowout preventer that failed to stop the oil from leaking, Transocean said its investigation determined that the device and its control system were fully operational at the time of the incident and functioned as designed. Its report said minor leaks identified before the incident did not adversely affect the functionality. Transocean blamed the high flow rate of hydrocarbons from the well for preventing the device from sealing on the drill pipe. Transocean, as owner of the rig, was responsible for maintaining the blowout preventer.
The official U.S. government investigation previously blamed the failure of the Cameron-made blowout preventer on a design flaw and a bent piece of pipe. It also suggested that actions taken by the Transocean rig crew during its attempts to control the well around the time of the disaster may have contributed to the piece of drill pipe getting trapped.
At least one outside expert said at the time that the government findings cast serious doubt on the reliability of all the other blowout preventers used by the drilling industry.
BP wasn't satisfied that the official investigation conducted all of the necessary tests to determine the cause of the blowout preventer failure. It got court approval for additional testing, which has been conducted in recent weeks.