WASHINGTON — Halliburton officials knew weeks before the fatal explosion of the BP well in the Gulf of Mexico that the cement mixture they planned to use to seal the bottom of the well was unstable but still went ahead with the job, the presidential commission investigating the accident said on Thursday.
In the first official finding of responsibility for the blowout, which killed 11 workers and led to the biggest offshore oil spill in American history, the commission staff determined that Halliburton had conducted three laboratory tests that indicated that the cement mixture did not meet industry standards.
The result of at least one of those tests was given on March 8 to BP, which failed to act upon it, the panel’s lead investigator, Fred H. Bartlit Jr., said in a letter delivered to the commissioners on Thursday. “There is no indication that Halliburton highlighted to BP the significance of the foam stability data or that BP personnel raised any questions about it,” Mr. Bartlit said in his report.
Another Halliburton cement test, carried out about a week before the blowout of the well on April 20, also found the mixture to be unstable, meaning it was unlikely to set properly in the well, but those findings were never sent to BP, Mr. Bartlit found after reviewing previously undisclosed documents.
Although Mr. Bartlit did not specifically identify the cement failure as the sole or even primary cause of the blowout, he made clear in his letter that if the cement had done its job and kept the highly pressurized oil and gas out of the well bore, there would have been no accident.
“We have known for some time that the cement used to secure the production casing and isolate the hydrocarbon zone at the bottom of the Macondo well must have failed in some manner,” he said in his letter to the seven members of the presidential commission. “The cement should have prevented hydrocarbons from entering the well.”
The failure of the cement set off a complex and ultimately deadly cascade of events as oil and gas exploded upward from the 18,000-foot-deep well. The blowout preventer, which sits on the ocean floor atop a well and is supposed to contain a well bore breach, also failed.
In an internal investigation, BP identified the faulty cement job as one of the main factors contributing to the accident and blamed Halliburton, the cementing contractor on the Macondo well, as the responsible party. Halliburton has said repeatedly in public testimony that it tested and used a proper cement formula and that BP’s flawed well design and poor operations caused the disaster.
Jesse Gagliano, a Halliburton technical adviser, told federal investigators in Houston in August that the company was confident of the cement job and said that BP’s decision to use six well-stabilizing devices known as centralizers contributed to the failure of the cement work.