BP Plc’s internal investigation of the Deepwater Horizon rig disaster found company engineers misinterpreted pressure data that indicated a blowout was imminent, according to a person familiar with the report.
BP managers aboard the Transocean Ltd.-owned rig misread a test of the Macondo well’s stability on April 20 and began replacing drilling fluid, which is heavier than oil and natural gas, with seawater, said the person, who spoke on condition of anonymity because the report’s findings haven’t been publicly released.
The seawater was too light to prevent natural gas that had begun leaking into the well from shooting up the pipe to the rig, where it exploded and killed 11 workers. The damaged well eventually spewed more than 4 million barrels of crude into the sea, enough to fill two supertankers.
BP intends to announce the findings of their internal probe in the next 10 days, the person said. Scott Dean, a U.S.-based spokesman for BP, didn’t return messages left after regular business hours on his office and cellular phones.
The 200-page report was compiled by a team of BP investigators led by Mark Bly, the London-based company’s head of safety and operations. The report concluded BP bears at least partial responsibility for the incident that led to the largest oil spill in U.S. history, the person said. Bly’s team also found that Transocean shares the blame, the person said.
Bly’s team began conducting interviews and reviewing internal documents just days after the Macondo well erupted about 40 miles (64 kilometers) off the Louisiana coast in the Gulf of Mexico.
Interviewees included BP vice presidents, offshore managers and engineers who designed the well in the company’s Houston office, according to testimony last week at a joint U.S. Coast Guard-Interior Department investigative hearing.
The catastrophe spurred probes by the U.S. Justice Department and several Congressional committees. BP suspended billions of dollars in dividends to preserve cash to pay for damages from the oil spill and efforts to stop the flow of crude a mile (1.6 kilometers) beneath the sea surface. The company saw the value of its stock tumble as much as 54 percent.
Four months after the incident, deep-water oil exploration remains on hold in the Gulf while federal regulators mull tougher safety rules to prevent future accidents. The Macondo field held an estimated 50 million barrels of crude before the spill.
The findings in BP’s internal report track the same series of events and decisions being examined by the Coast Guard-Interior Department panel, which finished its fourth round of public hearings last week in Houston. A fifth round of sessions is scheduled for early October.
The 8-member panel asked BP representatives on Aug. 26 to turn over a copy of the Bly report as soon as possible. The panel has been relying in part on notes from interviews BP conducted with employees involved in the Macondo well, including Donald Vidrine, the senior manager overseeing the project aboard the Deepwater Horizon on the night of the disaster.