"Mr. Newman of Transocean says in his prepared testimony that it "simply makes no sense" to blame the blowout preventer. At the point that the blowout occurred, "the well barriers—the cementing and the casing—were responsible for controlling any pressure from the reservoir," his testimony says."
Not sure what they were doing at the exact moment the kick occured, maybe they were in the act of displacing. Not true about the mud... mud has greater density, thus more more force on bottom hole. The mud was helping weight down the plug... when the mud was replaced with seawater, that weight was greatly reduced. And it doesn't take much pressure to cause what happened. In the House hearing they actually showed a Hal chart that measured the kick (around 2800psi) about 3 min before all hell broke loose.
Mr newman is correct the cement plug inside the pipe is suppose to keep anything coming up the inside until the production rig reenters the hole to set in production tools .The annulus or that space between the last set of casing is held by cement .My experience is 10 years in the oilfield drilling on land.
What I thought I heard today was that the decision was made to replace mud with water before final cementing to plug and pull off. Sounds to me like Halliburton and Cameron are off the hook. BP, as operator, would have designed the casing string, the cementing, and made the decision to cement the well after removing the mud. Sounds like a tragic error of judgment that might most times have been OK, but this time wasn't? I heard there was a rush to move to the next location. RIG's $500K/day dayrate affected BP company man's decision making?
I think there are 3 separate issues here 1) what caused the explosion, 2) why BOP not activated/functional during the blowout to prevent the explosion, 3) why BOP not fully functional after the explosion to stop the spill.
RIG CEO's testimony may exonerate CAM regarding #1. #2 and #3 still matter to CAM. The problem is made worse by the 3 weeks of spill after the blowout and explosion, the whole industry looks clueless after spending 3 weeks not able to stop the spill even with the best resource/technology/engineer.
There are some real good discussions on a blog called The Oil Drum you might check out. It seams to be leaning:
1) The cement that sealed up the casing failed. This is common, so it has to be tested very carefully (more cement is pumped in if need be). Somehow BP though the cement job was sound when it wasn't. After that as the removed some mud in preparation for closing the well this released pressure and the oil/gas rose up and blew out.
2) Human error. Once the cement job was known good they got sloppy and stopped watching carefully. There would have been clear indication of the impending blowout because extra mud had to come out first. They missed this. So nobody pushed the button.
According to the latest news the shear rams did activate.
From Forbes- "A BP spokesman says engineers have also made progress in understanding what went wrong with the blowout preventer. It turns out that the shear rams on the BOP did activate and close on the pipe, but that the oil is escaping out from around the sides of the BOP. "
The rams probably closed on a riser joint or on the drillstring which also would not be CAMS fault.