[Update: Looking again over the letter from the commission’s investigator, Fred Bartlit, it’s not obvious how clear Halliburton’s one warning to BP on the cement test were. From the letter:
Halliburton provided data from one of the two February tests to BP in an email dated March 8, 2010. The data appeared in a technical report along with other information. 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. There is no indication that Halliburton provided the data from the other February test to BP.
If Halliburton really failed to highlight the problems with the cement test to BP, and simply buried the data in a vast technical report, that would seem to shift more of the blame to Halliburton—although at the end of the day, it is still BP’s well. And as Bartlit notes at the end of his letter, since there’s always a risk that cement jobs can be faulty, there are tests that can be done to doublecheck the quality—and BP and Transocean, the company actually operating the Deepwater Horizon, did not seem to perform these tests. More info will be forthcoming as the companies respond, but right now it’s not looking good for Halliburton—the company’s share prices are already down by 8%.]
Original post: In the first official finding of responsibility for the Deepwater Horizon catastrophe—the worst oil spill in U.S. history—the presidential commission investigating the accident found that both Halliburton and BP knew before the explosion on April 20 that the cement mixture that was meant to seal the Macondo well was unstable. Despite that fact, they still went ahead with the work, setting the stage for the accident. The staff found that Halliburton—in charge of cementing the Macondo well—had conducted four laboratory tests that indicated the cement mixture standards wasn’t up to industry standards. The results of at least one of those tests was given to BP on March 8, yet BP failed to act on it. Another Halliburton cement test was carried out about a week before the Deepwater Horizon blowout—and the test also found the cement was unstable—yet the results were never sent to BP.
All of this new information comes from tests done by the oil company Chevron at the request of the White House-appointed National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling. (Download Chevron’s report as a PDF here.) In a letter to the commission—which is led by former Environmental Protection Agency head William Reilly and former Florida governor and senator Bob Graham—lead investigator Fred H. Bartlit summed up the results of the tests (download the letter as a PDF here):
(1) Only one of the four tests discussed above that Halliburton ran on the various slurry designs for the final cement job at the Macondo well indicated that the slurry design would be stable;
(2) Halliburton may not have had—and BP did not have—the results of that test before the evening of April 19, meaning that the cement job may have been pumped without any lab results indicating that the foam cement slurry would be stable;
(3) Halliburton and BP both had results in March showing that a very similar foam slurry design to the one actually pumped at the Macondo well would be unstable, but neither acted upon that data; and
(4) Halliburton (and perhaps BP) should have considered redesigning the foam slurry before pumping it at the Macondo well.
It’s not news that a problem with the cement was one of the main reasons the Macondo well suffered a catastrophic blowout—in its own internal investigation, BP identified the faulty cementing job and placed much of the blame on Halliburton. For its part, Halliburton has always defended its cementing job, and shifted the blame back to BP for a poor well design. But the tests done by the commission clearly show that there was something wrong with the cement Halliburton had been using. Halliburton gave the investigators samples of the same cement recipe that had been used on the Macondo well. (Chevron’s labs and experts were used for independent tests—which marks the umpteenth time during the spill and its aftermath that the government has had to essentially rely on the industry to police itself, because Washington lacks the proper expertise.) That mixture at Chevron failed nine separate stability tests that replicated the conditions of the Macondo well. The cement never passed.
It’s not clear why BP failed to act on Halliburton’s first warning, nor is it clear why Halliburton apparently failed to inform BP of further test failures closer to the date of the blowout. (Neither company has commented yet.) At the same time, as Bartlit wrote to the commission, the faulty cement is unlikely to be the sole cause of the blowout:
We want to emphasize that even if our concerns regarding the foam slurry design at Macondo are well founded, the story of the blowout does not turn solely on the quality of the Macondo cement job. Cementing wells is a complex endeavor and industry experts inform us that cementing failures are not uncommon even in the best of circumstances. Because it may be anticipated that a particular cement job may be faulty, the oil industry has developed tests, such as the negative pressure test and cement evaluation logs, to identify cementing failures. It has also developed methods to remedy deficient cement jobs.
BP and/or Transocean personnel misinterpreted or chose not to conduct such tests at the Macondo well.
Coming during a week when BP was once again under fire for its previous safety problems—and just a few days after new BP CEO Robert Dudley defended his company’s safety record—the oil spill commission’s investigation shows that something went seriously wrong aboard the Deepwater Horizon. We know now this accident could have been avoided. What’s frightening is that there’s no way to be sure it couldn’t happen again.
More from TIME on the Gulf oil spill: