Why did the blowout preventer not close ? That's its function and purpose - to prevent blowouts from traveling past the wellhead. No explanation has been given for that. The rumor was that a rig hand said BP knew it wasn't working and continued anyway.
How come the cementing job blew out ? Was it sufficiently cured ? I've heard comments that they did not allow sufficient time for a full cure. Also that it was the wrong cement. What's the truth ?
Why did they use seawater to balance the well ? A critical factor in drilling is controlling the pressure in the wellbore. A major factor in that is what fluid is being used. Typically the "mud" used is really a highly engineered concoction, with sufficient density to restrain the oil and gas from travelling up the wellbore, yet light enough to keep it from flowing into the producing strata. But seawater is much less dense than the typical drilling mud. Were they trying to save a few bucks ? Or was seawater actually expected to balance the well pressures ? For sure it didn't work.
The ultimate boss on any drilling rig is "the company man", in this case a BP employee. He or she makes the decisions. In this case it seems three poor ones were made:
1)going ahead with a malfunctioning blowout preventer;
2)an improper cementing job either insufficiently cured or wrong design;
3)using seawater to balance the well.
Well, here’s the bottom line -— THEY HAVE TO FIND OUT WHAT CAUSED THIS RIG TO GO DOWN.
If an accident, what was the source ?
If a sabotage, who did it ?
If we don’t know the cause of this, we will not be able to prevent a next one from happening.
Has this been confirmed? I have read no evidence at all that the cementing job that Halliburton performed that sealed the area between the outside of the casing and the borehole has failed. I have seen and participated in lots of discussion that cementing of the casing itself was deferred under direction by BP until the mud was removed from the casing. That just doesn't make sense to me at all; I don't care what pressure tests they ran. They had apparently experienced several pressure spikes leading up to the incident even when driller's mud was in place, so how could removing that mud have had any positive results?
Also, there have been several discussions about three plumes of oil and gas coming up; but although the investigation may determine otherwise, I suspect these plums came up through the blowout preventer piping. Remember that the blowout preventer had apparently been modified by BP, and reports were that drawings of the modifications may not even exist. This appears to be common when construction folks take the engineers' design and implement it. That may very well explain why attempts at activating the BOP didn't work. Perhaps they were operating the wrong valves? Nobody knows yet, but when they retrieve the BOP, it needs to be examined in the open by a group of proper experienced professional so that nothing can be hidden.