Halliburton and BP knew risk before spill

Gulf of Mexico well had ‘unstable’ cement

FT.com

Halliburton and BP had data weeks ahead of the Gulf of Mexico oil spill that showed the cement mixture the companies used to seal the well was unstable, but did not act on the information, according to a report by the US National Commission investigating the Macondo spill.

Tests performed for the investigative panel by industry experts strongly suggested that a mixture that was identical to the base cement slurry that Halliburton used on the well was not suitable. The deficiency “may have contributed” to the blow-out, which killed 11 men and pumped nearly 5m barrels of oil into the sea.

The first official finding by the federal panel raised new questions about why neither BP nor Halliburton verified the safety of the cement used before the cementing job was complete. Legal experts with knowledge of the matter say investigators at the US Department of Justice will use the commission’s probe as an important factual record.

Halliburton, which served as a contractor to BP and was responsible for cementing the well, has stated publicly that tests it performed on the cement mixture showed it was stable. But investigators on Thursday said in a letter to the commission’s board that Halliburton documents contradicted those claims. Shares in the US company fell 8 per cent.

In a press release, Halliburton said it did not believe that cement issues were the cause of the well rupture.

According to investigators, two cement tests that Halliburton conducted in February, which used a slightly different composition, showed the design was “unstable”. The result of one of the failed tests was emailed to BP on March 8 in a technical report, though investigative staff said there was no evidence that Halliburton highlighted the result.

Halliburton conducted two additional tests in April, seven days before the blow-out, which showed the cement was unstable, though the data did not appear to have been provided to BP. A final test – which may have been completed only after the cement was already poured into the well – found that the cement design was stable. The information was reported to BP after the explosion.

“The cement job may have been pumped without any lab results indicating that the foam cement slurry would be stable,” the letter said. “BP and/or Transocean personnel misinterpreted or chose not to conduct tests [to identify cementing failures] at the well.”

BP, Halliburton and Transocean, which owned the rig, did not comment.

BP’s own internal report highlighted the failure of the cement job, while Halliburton has claimed BP’s well design was principally at fault.