Thus the industry has for decades relied on a dense mud system to keep the hydrocarbons in the reservoir and everything that is done to maintain wellbore integrity is tested, and where a wellbore integrity test fails, remedial action is taken.

WSJ: The Oil Disaster Is About Human, Not System, Failure

At 8:20 p.m. on the day of the explosion the pressure data suggest there was a constant flow of sea water being pumped into the drill pipe that was displacing the heavier mud system which was the primary pressure control for the well.

WSJ: The Oil Disaster Is About Human, Not System, Failure

When the oil and gas reached the rig, they were diverted not overboard, as might have been wiser, but to a system called the mud-gas separator which spewed gas back onto the rig.

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Given the two red flags that had been thrown up previously, one would have expected that as a precaution a cement plug would have been placed somewhere in the wellbore as a secondary pressure seal before this primary pressure control system (heavy mud) was evacuated from the wellbore.

WSJ: The Oil Disaster Is About Human, Not System, Failure

"Obama, to his credit, got through this system with very little mud on his suit, " said David Mendell, a Chicago journalist and the author of an Obama biography.

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