Oil spill commission releases preliminary conclusions on cause of Macondo well blowout
Staff for the national oil spill commission released preliminary conclusions today regarding the cause of the April 20 Macondo well blowout, which led eventually to the massive Gulf oil spill.
Commission staff said they have found no evidence to suggest that there was an effort by BP or any other company involved in the oil spill to prioritize profits over safety, as a ProPublica/Frontline investigation into BP’s corporate culture suggests.
The staff also said that BP and Transocean misread a key pressure test of the Macondo well, just hours before the blowout, though Fred Bartlit, the commission’s chief counsel, could not determine why the test was misread. At the same time, commission staff pointed to data that showed there were problems with the cement mixture used in the well, arguing that the test results “should have prompted redesign of [the] cement slurry.”
Here are the preliminary conclusions:
- Flow path was exclusively through shoe track and up through casing.
- Cement (potentially contaminated or displaced by other materials) in shoe track and in some portion of annular space failed to isolate hydrocarbons.
- Pre-job laboratory data should have prompted redesign of cement slurry.
- Cement evaluation tools might have identified cementing failure, but most operators would not have run tools at that time. They would have relied on the negative pressure test.
- Negative pressure test repeatedly showed that primary cement job had not isolated hydrocarbons.
- Despite those results, BP and TO personnel treated negative pressure test as a complete success.
- BP’s temporary abandonment procedures introduced additional risk.
- Number of simultaneous activities and nature of flow monitoring equipment made kick detection more difficult during riser displacement.
- Nevertheless, kick indications were clear enough that if observed would have allowed the rig crew to have responded earlier.
- Once the rig crew recognized the influx, there were several options that might have prevented or delayed the explosion and/or shut in the well.
- Diverting overboard might have prevented or delayed the explosion. Triggering the EDS prior to the explosion might have shut in the well and limited the impact of any explosion and/or the blowout.
- Technical conclusions regarding BOP should await results of forensic BOP examination and testing.
- No evidence at this time to suggest that there was a conscious decision to sacrifice safety concerns to save money.