Criminal investigators on the Justice Department's Deepwater Horizon task force are looking into whether oil company BP failed properly to report changes in a key pressure measurement that would indicate how difficult the well was to control, officials familiar with the investigation told the Houston Chronicle.
In particular, they point to an April 13, 2010, e-mail written by a BP geological operations manager explaining why BP stopped drilling in the Macondo Prospect oil field where the Deepwater Horizon drilling-rig explosion and fire occurred April 20, 2010.
The explosion and fire, which killed 11 workers and injured 16 others, led to the largest accidental oil spill in history. It took 87 days to get under control.
The e-mail came up during dozens of depositions taken in the massive collection of civil suits consolidated into a federal court in New Orleans, the Chronicle said.
The oilfield services contractor Halliburton Co., responsible for cementing operations, has pointed to the e-mail as proof BP officials knew they had a highly difficult well on their hands and were taking unnecessary risks, the newspaper said.
The central cause of the Deepwater Horizon explosion was a failure of the cement at the base of the 18,000-foot-deep well that was supposed to contain oil and gas within the well bore, a Sept. 14 Interior Department and Coast Guard report said.
The failure led to a cascade of human and mechanical errors that allowed natural gas under tremendous pressure to shoot onto the drilling platform, causing the explosion and fire, the report said.
The report said the oil giant was "ultimately responsible" for the accident, but said rig owner Transocean Ltd. and Halliburton shared some of the blame.
BP last week filed its first permit application for new drilling since the spill.