WASHINGTON — Houston-based Halliburton knew that the cement it was using to seal BP's Deepwater Horizon oil well was likely to be unstable, but it didn't tell BP or act on the information internally before the well blew up April 20, the staff of the presidential commission that's investigating the disaster reported Thursday.
In a letter to the commission's seven members, the staff says the failure of the cement was a key factor in the blowout, which resulted in millions of barrels of crude oil escaping into the Gulf of Mexico in a torrent that went largely unchecked for three months.
But the staff also took pains to point out that unstable cement wasn't the sole factor _ or even the most crucial one _ in the well's failure. That blame, the letter says, belongs to BP and Transocean, the company that BP had hired to drill the well.
"Industry experts inform us that cementing failures are not uncommon even in the best of circumstances," the letter says. "Because it may be anticipated that a particular cement job may be faulty, the oil industry has developed tests . . . to identify cementing failures."
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"BP and/or Transocean personnel misinterpreted or chose not to conduct such tests at the Macondo well," the letter concludes.
The letter adds to the growing body of evidence that at least at the Deepwater Horizon drilling site, the safety procedures that are intended to head off such accidents were ignored or overlooked. BP acknowledged in a September report that its internal investigation had found that cementing tests were misinterpreted or weren't run.
In its letter Thursday, the commission staff expressed concern that similar oversights were widespread in the offshore drilling industry.
"We want to report these results immediately to facilitate your consideration of their implications for offshore drilling safety," the letter says.
Oil drilling companies use cement to seal an exploratory well such as the Deepwater Horizon one as the last step before assigning a drilling rig to another location. Once the seal is in place, technicians remove heavy drilling mud from the well and replace it with lighter seawater. It was during this step that hydrocarbons surged up the Deepwater Horizon drill pipe, enveloped the rig in a cloud of methane and exploded, killing 11 rig workers and setting off the largest accidental spill in history.
Halliburton is one of the world's largest providers of oil well cementing services and its reach extends not only to the Gulf of Mexico but also to deepwater drilling sites throughout the world. A bad Halliburton cement job is suspected in the explosion last year of a well in the Timor Sea near Australia.
The letter, signed by commission counsel Fred H. Bartlit Jr. and two other staff members, came just two days after Chevron reported the results of efforts it made, using materials provided by Halliburton, to duplicate Halliburton's cementing mixture. In every instance, Chevron reported, the procedures it followed failed to produce stable cement.
"We were unable to generate stable foam from any of the tests," Chevron's cementing team leader, Craig Gardner, told the commission in a letter.
Chevron conducted the tests "as a public service" at the request of the commission, Bartlit says in his letter. "Halliburton agreed that the Chevron lab was highly qualified for the work," the letter says.
The Chevron results should have come as no surprise to Halliburton or BP, Bartlit's letter suggests. He says that when the Chevron results came in, the commission asked Halliburton for its own internal test results, which Halliburton provided. Those documents showed that at least three of four tests Halliburton conducted had found that the cement would fail, the commission staff letter says.
"The first two tests were conducted in February 2010," the letter says. "Both tests indicated the foam slurry design was unstable."
Halliburton did pass the data from one of the February tests to BP on March 8 in a technical report. But Halliburton didn't highlight the significance of the test and there was no indication that "BP personnel raised any questions about it," the letter says.
Another test conducted in April had similar results, but "it appears that Halliburton never provided the data to BP," the letter says.
A fourth test, conducted after Halliburton changed its testing procedures just days before the explosion, showed that the cement mixture would be stable, but it was unclear whether the testing had been completed before the cement was poured. The results of that test weren't provided to BP until after the well exploded, the letter says.
President Barack Obama appointed the commission earlier this year to investigate the causes of the disaster and recommend new regulations to prevent a similar crisis. The commission is co-chaired by former U.S. Sen. Bob Graham, D-Fla., and William K. Reilly, who was the head of the Environmental Protection Agency under President George H.W. Bush.
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