A series of decisions raised risks at BP’s Macondo well, culminating in the fatal explosion of the Deepwater Horizon drilling rig, a presidential commission said today.
Although the panel won’t release its final report until Jan. 11, it outlined its 13 preliminary findings today. They are:
1. Flow path was exclusively through shoe track and up through casing.
The commission’s initial determination that flammable natural gas flowed up through the center of the well, rather than the annulus between the drill pipe and the well hole, matches the conclusion of BP’s internal investigation.
2. Cement (potentially contaminated or displaced by other materials) in shoe track and in some portion of annular space failed to isolate hydrocarbons.
The cement job at the bottom of the well and outside edges of the well failed to provide a full barrier between it and oil and gas.
3. Pre-job laboratory data should have prompted redesign of cement slurry.
Laboratory tests of the nitrogen-injected foam cement used at BP’s well more than a month before it was applied at the site indicated some stability problems. That should have prompted a second look, said Fred Barlit, the commission’s chief counsel and top investigator. “We think maybe more time should have been spent getting consistent results,” Bartlit said. “Most of the lab results show this stuff works better … if you stir it for three hours and then you foam it.” But that didn’t happen on the rig — when the order is reversed.
4. 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.
“BP conceded in its report that maybe if it had done a risk assessment at that time … maybe they would have run the cement bond log instead of sending Halliburton home,” Bartlit said. “But we don’t know what the cement bond log would have shown.”
5. Negative pressure test repeatedly showed that the primary cement job had not isolated hydrocarbons.
Workers on the rig misinterpreted a crucial negative pressure test as being successful.
6. Despite those results, BP and Transocean personnel treated negative pressure test as a complete success.
7. BP’s temporary abandonment procedures introduced additional risk.
Commission investigators questioned whether BP boosted risk by constantly changing its plan for securing and abandoning the well at the conclusion of drilling. But Bartlit also faulted BP’s decision to set a temporary abandonment plug unusually low, near the payzone.
8. The number of simultaneous activities and nature of flow monitoring equipment made kick detection more difficult during riser displacement.
It is unclear whether data that could reveal kicks — or incursions of gas into the well — was actively monitored when drilling was completed and workers were in the process of displacing drilling muds with seawater in preparation for temporarily abandoning the well.
9. Nevertheless, kick indications were clear enough that if observed they would have allowed the rig crew to have responded earlier.
10. 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.
11. 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.
Workers on the Transocean rig chose not to divert the fluids coming up from the well over the rig — a choice that may have allowed gas to vent onboard, where it could ignite. A decision to trigger emergency devices also may have helped prevent a disaster, but, Bartlit noted, by the time gas got to the surface, there was a mile of riser pipe filled with it.
12. Technical conclusions regarding the BOP should await results of forensic BOP examination and testing.
Although the blowout preventer was a crucial line of defense against a disaster, we still don’t know enough about the one that failed to slash through drill pipe and cut off flowing gas at BP’s Macondo well. The blowout preventer is now at a NASA facility in Louisiana where it awaits a battery of tests.
13. There’s no evidence at this time to suggest that there was a conscious decision to sacrifice safety concerns to save money.
“We don’t see a person or three people sitting there at a table considering safety and cost and giving up safety for cost,” Bartlit said. But, he added, that doesn’t mean the costs of the project — about $1.5 million dollars every day — wasn’t in the back of some workers’ minds. “We know that a million and a half dollars a day is a lot of money,” Bartlit said. Workers on the rigs and at shore “want to be efficient, and they don’t want to waste money, but they don’t want their buddies to get killed. I don’t believe people sit there and say this is really dangerous, but the guys in London will make more money. It’s more complicated than that. What we’re saying is that the human beings who made the decision — shoreside and on the rig — we don’t see a conscious decision where human beings made a tradeoff of safety for dollars.”