Friday, June 18, 2010

Well Bore Condition Update, kinda

On Monday, I posted an item on the integrity of the Macondo well that's currently spewing as much as 60,000 barrels of oil daily into the Gulf.  Some self-described experts in oil & gas drilling and production have expressed concern that the structural integrity of the well itself has been compromised and that the reason why the top kill procedure failed was because mud was escaping through cracks or holes in the casing of the well.  They point to the enormous amount of drilling mud used in the process as evidence that oil is escaping the well.  In yesterday's operations briefing, US Coast Guard Admiral Allen was asked about this, and here is the exchange:

[Brian Hartman, ABC News] Q: Yes, hi. Thanks, Admiral. Do you believe the well pipes themselves are broken or leaking at all? And do you have any concerns about the integrity of the blow out preventer, the well borer [sic], the sea floor that’s holding up the blow out preventer? Thanks.

ADMIRAL ALLEN: That’s a terrific question. Let me kind of take it in sequence. We have some idea of the condition of the blow out preventer and lower marine riser package. In combination, they call that the stack that sits above the well head itself. We know from some sonic testing that was done based on radiography equipment from the Department of Energy we have a partial closer of some of those rams but not a complete closer. And that was a problem for the top kill operation because we could not get enough pressure on top of the blow out preventer to force all of the mud down into the well bore to allow us to top kill it, if you will.

So we know that the, that there is, there is, and we also know that there is product rising up through the blow out preventer through the, where we cut the lower marine riser pipe. We’re not going to know the exact condition of that blow out preventer until we’ve capped the well, can remove the blow out preventer and bring it to the surface.

I’ve said on several occasions, I consider that blow out preventer almost the equivalent of this incident of the black box we would be seeking to find after an aviation accident because it can reveal a lot of information related to what happened at the time of the event. And the blow out preventer was key to that.

As you move below that and you go down into the well bore, I think that one thing that nobody knows is the condition of the well bore from below the blow out preventer down to the actual oil field itself. And we don’t know, we don’t know if the well bore has been compromised or not. One of the reasons we did not continue with top kill at higher pressures, there was a concern that if we increased the pressure too hard it might do damage to the casings and the well bore. What we didn’t want was open communication of any oil from the reservoir outside the well bore that might get into the formation and work its way to the sub sea floor and then result in uncontrolled discharge at that point. That has not happened and that’s the reason they’re taking such precautions and did not proceed any further with the top kill.

What we are doing is going down the very bottom of the well bore for this intercept and hopefully at that point they will start pumping mud in. And mud will first go up all the way and fill the well bore and then it will be forced down over the oil into the reservoir and then put enough weight of the mud to hold the oil in the reservoir. And then allow them to put a cement plug in after that.

So what I would tell you is we don’t know exactly the condition of the well bore. And that’s one of the unknowns that we’re managing around in terms of risks. And that’s the reason we didn’t go, didn’t go to excessive pressures on the top kill and decided that we’d deal with containment and then go for the final relief well.

Three things stand out here:  First, Allen says sonic and radiographic tests indicate that when the blowout preventer was engaged, the rams (hardware that mechanically crush and shut off the well pipe) were able to partially close the well, but not enough to prevent a massive flow of crude.  And secondly, Allen believes it was this partial blockage of the well that doomed the top kill procedure.

But thirdly, and most importantly of all, the actual condition of the well bore itself is not known, and probably won't ever be known, unless the worst case scenario--as described in the item I posted about Monday--actually plays out.   If the relief well is successful in stopping the flow, the well will be filled with mud and capped with cement, permanently sealing it forever and ever, Amen.  But if the relief well fails to stop the flow, the reason would almost certainly be a badly compromised well bore that lets mud escape the well.  Escaping mud would mean engineers on the surface are not creating enough pressure to contain the oil flow.

To make a long, sleeper of a post shorter, Allen's comments are somewhat encouraging, but since almost nothing has gone right in this slow motion disaster, there's still not a lot of confidence floating around out there.

Gimme some feedback in the comments.


Anonymous said...

We're screwed.