On 28 October, Fred H Bartlit, the chief investigator for the National Commission on the BP Deepwater Horizon Oil Spill, sent a letter to the commission outlining some of the preliminary results learned from an analysis of the cement used in the Macondo well.
The letter from Mr Bartlit explained that the commission instructed Chevron to run tests on a batch of cement slurry provided by Halliburton, which was similar to that used in the Macondo well. When Chevron's tests found the mix to be unstable, investigators asked that Halliburton hand over all the data on the tests it had run on the cement.
The letter stated: ‘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.’
In response to the letter, Halliburton released a statement that the commission tested off the shelf cement and additives, whereas the company tested the unique blend of cement and additives that existed on the rig at the time its tests were conducted. It added it has been unable to provide the commission with cement, additives and water from the rig because it is subject to a federal court preservation order, although the materials will soon be released to the Marine Board of Investigation.