IMR 4350 seems to have the key info on this [quote]
At 30,000psi of pressure you don’t need an explosion. Crap just starts coming apart.
The gas ignited when it got to the surface and settled into the rig.
From all acounts here is the screw up.
They assumed the cement held and they opened the BOP with that assumption. The cement didn’t hold and a gas bubble shot up to the well.
[unquote]
There was a guy on with I believe it was Mark Levin, he was on the rig. Somebody provided a link last night.
It was just an accident.