Posted on 05/31/2010 2:38:39 PM PDT by omega4179
Very interesting.
(Excerpt) Read more at bp.com ...
I agree.. I think they’re just checking the overall well integrity with the addes backpressure of the cap.
Most likely, have not started trying to make the seal... yet.
7th
That is what we all are looking for, but I would really not count chickens before they hatch here.
agree
You don’t see the entire BOP rocking back and forth?
It turns out, apparently, there is no seal.
so.. what is this they are spraying? More Methanol? Does this mean, they have methane rock problems again? Or, are they conditioning the O-ring before making the seal?
See a more technical discussion here on an engineers news group:
http://www.eng-tips.com/viewthread.cfm?qid=272697&page=1
Relevant quotes - from engineers I trust far more than anyone on ABCNNBCBS on that thread:
“Based on an analysis of the fluid velocity out the vent, one of my friends at BP estimated a flowing “wellhead” pressure over 15,000 psig. That makes reservoir pressure in the neighborhood of 25,000 psig.
People keep saying “why can’t they just stick a plug in the pipe?”. It would be much like hanging a plumb bob on the end of a string and trying to force it into the end of an operating power washer.”
“I think the 25k bottom hole pressure estimate is pretty reasonable. I got 22.5 myself, but probably a little low because I didn’t add the 2166 psi water pressure (or the 14.7 psi atmospheric pressure).”
“The riser is 21” OD, 1” wt (19” ID). The drill pipe is 6-5/8 OD, 1/2” wt (5-5/8” ID).
No one knows where the drill pipe ends as far as I can tell (there seems to be a lot of confusion about this, they can’t tell where the bit was when the elevators stopped due to the explosion). I would assume that the flow out the end is both annular and drill pipe, and the the flow from the holes in the riser are just annular.”
...-—...-—...-—
My own calc’s follow:
Assume “only” 6000 psi flow from a 21 inch diameter pipe with 1 inch walls:
Inside diameter of the outside pipe = 19 inches, area = 283 sq inches.
Outward force = 283 x 6000 = 1,700,000 pounds force = 850 tons.
(Now, some experts think the pressure inside the inner pipe is 15,0000 psi. Once the outside pipe is plugged, this pressure from the inside pipe fills the outside pipe and must be resisted:
15,0000 x 283 sq inches = 4,245,000 pounds force or 2122 tons.
So any theoretical “plug” anyone on TV is talking about must not go only be able to go back INTO the hole against 850 tons of force coming OUT of the hole, but it must (somehow) grip the walls of the pipe and continue to resist those 2122 tons of force after it is down inside in the hole.
Crimping the pipe cannot stop the flow completely, but it could reduce it - the crimped pipe however will lose its ability to resist the inside pressure, and so is likely to crack completely open up and down the pipe at the crimped point. Cracking is particularly possible at the cold temperatures down 5000 feet below.
Crimping force: There are many complications in calculating the actual crimping (collapsing and folding and buckling and bending and shearing (cutting) the steel are all going on at the same time. As a rough estimate, think of the force needed to simply shear an equal flat plate of simple steel.
Assume 70,000 psi shear strength. Area of metal of the two pipes that need to be sheared = pi(r_outside^2 - r_inside^2)
= 3.14 *(3.3125^2 - 2.8125^2) + 3.14 * (21^2-19^2)
= 9.616 + 251.2
= 260.8 sq inches
Force to shear an equal strength plate (which is related to force to crimp the pipes but isn’t exactly equal to it) =
70,000 psi * 260.8 sq inches = 18,200,000 pounds force.
And this force must be applied in that single limited area of the crimp - you can’t spread it out over a wide area.
(Note: I don’t know the actual strength of the BP drill pipe - Cheap steel is only 36,000 pounds strength, but that type isn’t used (shouldn’t be used) for drill steel.
Dispersant
Sure there is. It is evenly distributing the oil plume around the entire cap.
Note to self - Correct 15,0000 to 15,000 psi internal pipe pressure.
The leak that looks real bad must be a relief that they have opened so that the hat can be piped and sealed?
Spraying dispersant.
Even if this seal doesn’t work or the pipe is too small, they can replace them. As long as the integrity of the well is good, they can fix the rest in short order.
That is ture, I just meant that there are an endless number of ways it can still go wrong. I personally would feel bad about jinxing it at this point, maybe that is just me. We can both try to keep up hope of course. At least it seens the seal has not broken yet and the oil has not completely broken it yet. Unless it just happned now.
This is true, sorry about that. And also, it is also cuase for great concern since any and all delays they have at this point are going to lead to big political and economic consequences.
*Cause for concern, damn it, now I’m getting so tense I can’t type worth crap
It’s leaking out around were the top hat sits on the BOP. A seal if there is one would prevent this if inflated or top cap locked down. According to info above I’m now not sure that this design of the top cap included a seal. I’m not sure why they wouldn’t. If pressure was a concern then just leave the top valve open but then you might have blockage from methane crystal formation.
This is getting stranger now. I had thought just an hour ago they were getting ready to put a seal on and that is what the O Rings and stuff were for. Did they actually not have a seal to begin with, or just now get rid of the seal ? Just when it can’t get crazier.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.