Doomsday Scenario – Could The Well Casing Crack?

gCaptain
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June 18, 2010

Cracked Well Casing Macondo

For the past few days in internet forums and chat rooms an email has been circulating that’s being dubbed “The Doomsday Scenario“. Doug R, the anonymous author of the post, suggests the integrity of the Macondo well’s casing has been compromised. Yesterday Admiral Thad Allen held a press conference and, while not addressing the rumors directly, did confirm that BP has, for weeks, had concerns about the integrity of the well. Admiral Allen stated;

As you move below that (the BOP ) 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.

In a article posted today at The Atlantic, Lisa Margonelli asks important questions about flow rate estimates and Tony Hayward’s recent testimony. She writes:

The most important question (and one Tony CAN answer) was only hinted at by Rep. Scalise when he asked if the casing around the well was cracking. Hayward’s response was a variant of “I don’t know” because, he said, they can’t see into the well. Scalise dropped the line of questioning without asking Hayward to offer his best explanation for the increasing flow rate of the well.

Why is the integrity of the casing or the ground around the well hole important? Because it says everything about whether the flow rate of this spill will increase, whether there are more disasters yet to come, and how long it could take to stop flow from this well with the relief wells. The question I’d like to ask Tony Hayward is this: To the best of your knowledge are we near the end of this spill? In the middle? Or perhaps, only at the very beginning? Continue Reading…

In their recently published proposal, James Cameron’s team had similar concerns:

We believe that bending forces applied when the Deepwater Horizon burned and drifted out of control must have significantly stressed the bottom joint— and the BOP may be structurally compromised at its base.

Shortly after the explosion, the DPS (Dynamic Positioning System) on the rig failed leaving the rig floating without control in winds and ocean currents. (Although there was sufficient time to get tugs on scene, we could not find images of tugs keeping the rig in position. The USCG tentatively confirmed that no tugs were used.)

This means that the ship’s drift was arrested solely by tension on the riser and possibly the drill pipe. This would have bent the flex joint to its maximum limit and put enormous lateral loading on the top of the stack, with the highest stress point at the bottom connection just above the base plate. The BOP would have been a 45-foot long moment arm, with the entire force of a drifting drill rig applied to one end, generating powerful bending loads.

…..Leaks at or below the seafloor would be extremely difficult to contain. In the absence of knowing all the data available to BP engineers, it was deemed prudent for us to accept that figure and recommend plans that would work within the limits imposed by BP.

gCaptain questions Cameron’s conclusion given the fact that both the wind and current were minimal during the period in which the Horizon was floating disabled. But these concerns do lead us to one giant question; “What are the consequences of this doomsday scenario?”. Here are dougr’s thoughts:

All of these things lead to only one place, a fully wide open well bore directly to the oil deposit…after that, it goes into the realm of “the worst things you can think of” The well may come completely apart as the inner liners fail. There is still a very long drill string in the well, that could literally come flying out…as I said…all the worst things you can think of are a possibility, but the very least damaging outcome as bad as it is, is that we are stuck with a wide open gusher blowing out 150,000 barrels a day of raw oil or more. There isn’t any “cap dome” or any other suck fixer device on earth that exists or could be built that will stop it from gushing out and doing more and more damage to the gulf. While at the same time also doing more damage to the well, making the chance of halting it with a kill from the bottom up less and less likely to work, which as it stands now?….is the only real chance we have left to stop it all.

It’s a race now…a race to drill the relief wells and take our last chance at killing this monster before the whole weakened, wore out, blown out, leaking and failing system gives up it’s last gasp in a horrific crescendo. Continue Reading…

There is also the question “What is BP’s worst case scenario?” And, in asking this we are not referring to the official answer contained in a BP press releases, rather we are curious about the watercooler chatter being whispered by petroleum engineers and geophysicists. One gCaptain forum contributer might have the inside scoop.He tells us;

The DWH well has been a source for great debate among my family.. according to my father who retired after 30+ years of geology and geophysic the potential for this well to breach has been a reality since it blew out. His comment; “this is not new science..the longer it remains beyond control the greater the degradation and potential”..the “new science” is the learning curve we are now being taught in dealing with this at extreme pressures at extreme depth..one grass root principle of the physics of nature is that everything and everyone responds different when subjected to pressure.

While time will be the ultimate test of these theories gCaptain believes the USCG should prepare for the worst, the uncontrolled discharge of 150,000 BPD, while hoping for the best, the quick and successful drilling of the relief well.

UPDATE – Sat 19 June 10: A source close to gCaptain that wishes to remain anonymous sent us this observation:

I was looking at the ROVs from the BOA deep C working on the manifold on the bottom around 1330 central time & when the one turned away from the manifold there was a huge flow coming out between it & the well head. I hope it was a ruptured hose, because if it was coming out of the ground this well head won’t hold out another week.

UPDATE – Monday 21 June – The latest press conference transcript reads as follows:

Q: Admiral, good morning.

On the 18th you mentioned that there were some concerns or question about the integrity of the wellbore. I want to ask you if you have any information that raises those concerns in your mind. Have you got any reports from MMS or other engineers? What are the particular problems that you’re worried about and how might that play into effect when you’re going for the relief well or doing other operations?

So basically what’s your information on the status of the wellbore and how can that affect you going forward?

ADMIRAL ALLEN: Well, one of the issues is we don’t know the exact status of the wellbore.

A while back, in fact, many weeks ago when we were discussing the top kill operation, we were having a significant discussion and we had a two-hour conference call on a Sunday, which Secretary Salazar, Secretary Chu called a scientific summit. We were going through the parameters of the top kill procedure, and they were trying to establish threshold for how much mud they can put down there and how much pressure they wanted to create in the wellbore.

And there was some discussion at that point about the uncertainty of the—of the condition of the casings in the wellbore which you would want to do is drive so much mud down there and such a pressure that you might cause a problem and the problem was they didn’t know and they still don’t know the condition of the wellbore. For that reason, they erred on the side of safety on how much pressure they would exert, and when they got near those pressures without having success in killing the well—killing the well, that’s when they backed off.

So I’m not going to use any hard and fast scientific evidence or anything like that. I think there’s a general notion by everybody that there could be something in the wellbore that can be problematic. We don’t know because there’s no way to really check it. That’s the reason they ceased the top kill procedure where it was at and went to containment, and then relying now on the bottom killer, going into the bottom of the well near the reservoir to put the mud in and seal it from there.

When the mud goes in the wellbore, it will go up and down and fill it, and when it does that it’ll—if there’s any problem with the wellbore and the casings, it will just be mud going out into the formation or the strata and not oil. One of the reasons we’re venting the oil out of the containment cap right now is we don’t want to put too much pressure down in the well just in case there is a problem with the wellbore.

But it’s a generalized concern. I think everybody’s known it for a fair amount of time. It’s something just to be taken account when we’re laying out the plans.

Was that responsive?

Q: Is there any concern that you could have oil coming out of the formation if your—if your casing is compromised?

ADMIRAL ALLEN: I guess there could be, but I don’t think there’s any indication of that right now. That’s the reason they’re trying to produce all the oil that’s coming up through the riser pipe and venting the rest of it off. And that’s the reason they decided not to just put a cap on with another blowout preventer after the top kill was not effective, and I don’t think they knew to a virtual certainty what the condition of the wellbore was. They just did not want to take that chance.

….Q: Do you have any signs that the—there’s erosion? In other words, that the existing containment gear, the blowout preventer, et cetera, are failing in any way that could lead to a larger and larger flow? In other words, that you could be chasing a moving target in terms of flow?

ADMIRAL ALLEN: Nothing that we’re familiar with at this point. The entire arrangement is kind of listed a little bit. I think it’s 10 or 12 degrees off perpendicular so it’s not quite straight up. And that causes a little bit of a challenge in sealing this containment cap in the rubber seals around it.

But none that I’m aware of, but we will double check that. If there’s any change to that, we’ll make an announcement by tomorrow. But I think—I don’t think we have any indication that’s going on.

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