The Rising Influence of Rising Affluence

[Kadaicher1]

The Horizon blowout. I have been waiting to see what happened when the crew diverted the flow of gas at surface. They were using oil based mud. Restrictions in the Gulf are so strict that no one will make the decision to direct the drilling fluid overboard.
From WSJ
http://professional.wsj.com/article/SB10001424052748704505804575484053238831866.html?mod=wsjproe_hps_LEFTWhatsNews

"Workers had made another fateful decision in the first moments of the blowout: They had directed the gas and drilling fluid coming out of the well through a system on board the rig rather than straight overboard. Normally, that would have been the right decision. Dumping oil-based fluid overboard is a violation of federal law and could have drawn a substantial fine. The system on the rig was designed to capture the fluid and get rid of the gas.
But in this case, the sheer volume of gas overwhelmed the system. Transocean said in a statement that sending the flow through the on-board system was "the appropriate course of action for crew to take based on the information they had at the time." The company said that it wasn't clear whether workers diverted the gas overboard once they had realized the extent of the problem.

Within minutes, gas had surrounded the rig and was being sucked into the engines. Somewhere, likely in the engine room, the gas hit a spark and ignited."

A decision to divert oil based mud over the side, if in error, could be a career ending decision. This needs to be looked at in my opinion.
Back in '84 when the Zapata Lexington burned and killed 4 crewmembers, a similar decision was made for the same reason. Keeping oil based mud out of the sea.
If a kick gets through the BOP it will always overwhelm the system, considering the huge expansion of gas from the depth of that BOP. There is only one place for it and that is overboard. Maybe they need to stop the use of oil based drilling fluids.
We havn't come very far in 26years.
http://www.ocsbbs.com/accidents/86-0101.pdf
page5 & 6
From what I have read, it looks like they closed the annular, which is normal procedure. Then the next step of correct procedure can be a little tricky. Once the annular is closed, the pressure building underneath the annular element assists the close. It may be necessary to take the pressure very low to initially get the pipe to move.Then you bleed the annular close pressure back till the pipe will strip through the annular. When a tool joint goes through the annular the resistance can be seen, now you know where the tool joint is, a ram is closed and the tool joint rested on top of the rams. The rams can be locked in the close position. They didnt get that far. Maybe the gas was already through when they started the procedure, or they let the gas through during stripping, or the annular leaked because of poor condition of the element and/or too low initial closing pressure.