A Wall Street Journal investigation provides the most complete account so far of the fateful decisions that preceded the blast. BP made choices over the course of the project that rendered this well more vulnerable to the blowout, which unleashed a spew of crude oil that engineers are struggling to stanch.
BP, for instance, cut short a procedure involving drilling fluid that is designed to detect gas in the well and remove it before it becomes a problem, according to documents belonging to BP and to the drilling rig's owner and operator, Transocean Ltd.
BP also skipped a quality test of the cement around the pipe—another buffer against gas—despite what BP now says were signs of problems with the cement job and despite a warning from cement contractor Halliburton Co.
Once gas was rising, the design and procedures BP had chosen for the well likely gave this perilous gas an easier path up and out, say well-control experts। There was little keeping the gas from rushing up to the surface after workers, pushing to finish the job, removed a critical safeguard, the heavy drilling fluid known as "mud." BP has admitted a possible "fundamental mistake" in concluding that it was safe to proceed with mud removal, according to a memo from two Congressmen released Tuesday night.
Finally, a BP manager overseeing final well tests apparently had scant experience in deep-water drilling. He told investigators he was on the rig to "learn about deep water," according to notes of an interview with him seen by the Journal.
Some of these decisions were approved by the U.S. Interior Department's Minerals Management Service, which has come under fire for what President Obama has called its "cozy relationship" with the oil industry. But in at least one case, the decision made apparently diverged from a plan MMS approved. MMS declined to comment.
Some of BP's choices allowed it to minimize costly delays. "We were behind schedule already," said Tyrone Benton, a technician who operated underwater robots and worked for a subcontractor. He said that on the day before the accident, a Monday, managers "hoped we'd be finished by that Friday.... But it seemed like they were pushing to finish it before Friday."
He added: "They were doing too many jobs at one time।" Mr. Benton is suing BP and Transocean claiming physical injury and mental anguish.
BP started again in January, this time with Transocean's Deepwater Horizon, a warhorse rig that had worked for BP for years. BP filed a new drilling permit with federal regulators.
According to a company document seen by the Journal, BP approved spending $96.2 million and about 78 days on the well. The target time was much less—about 51 days. By April 20, the well was in its 80th day, owing to delays such as one that had begun on March 8.
That day, workers discovered that gas was seeping into the well, according to drilling reports from the rig reviewed by the Journal. Workers lowered a measuring device to determine what was happening, but when they tried to pull it back up, it wouldn't budge. Engineers eventually told them to plug the last 2,000 feet of the then-13,000-foot hole with cement and continue the well by drilling off in a different direction.
The episode took days to resolve, according to drilling reports, not counting time lost to backtracking and re-drilling. Each additional day cost BP $1 million in rig lease and contractor fees.
Other problems arose। The rock was so brittle in places that drilling mud cracked it open and escaped. One person familiar with the matter estimates BP lost at least $15 million worth of the fluid.
About 9:45, the seawater and remaining mud began to head back up the pipe. Witnesses say they saw mud shooting out of the derrick like water from a firehose. A worker on the rig floor made a frantic call to BP's Mr. Vidrine, who had gone to his office, according to his interview with the Coast Guard.
Transocean workers raced to tame the well. Nothing worked. This was no ordinary gas kick. It was far more ferocious.
Workers rushed to hit the emergency button to activate the blowout preventer's clamps and detach the rig from the well, according to witness accounts. They were too late. Gas flowing out found an ignition source, and an explosion rocked the rig.
