underwater metal working

Bill, Here's a site with some more technical info:

Somebody tell that guy the nut's 3 inches and his socket is 75mm.

Those underwater cams are a bit frustrating for me because I don't know enough to figure out what they're trying to do to help the situation. I like the oildrum site because it provides a bit more context for me.

This young lady seems to have the best solution. I think she should have stopped by the patient office first, but yea or nay, she does have a novel, and very practical idea.

She calls the plan the "seabed retread."

They are even more frustrating for me, because they are offered only in a Windows format. I don't have a way to view those on my systems. The oildrum site at least has things which I can view and read.

I just tried the Linux box, and it can't view the video feeds either.

Enjoy, DoN.

Try this

It works on my Ubuntu box. The BP feed wouldn't work.

technomaNge

She may or may not have an ingenious idea, but I see no evidence of it in the article you linked. How would you place such a plug and how would it stay in place in a pipe that may have 20 ksig at the outlet?

"has anyone figured out what they are measuring in the Boa Deep C ROV 2 video feed?

robot arm is holding a bracket like device with a cable going to it, they touch it to the pipe below the BOP or above the BOP for a while and then go somewhere else - I'm imagining it's some kind of ultrasonic transducer, but perhaps someone knows for sure

Ah Sorry. Looks like part of the address went missing...

Anchor the rig to the pipe first, then just pull it in and inflate the seal.

Thanks -- it works on Sun's Solaris 10 with Opera as a browser too.

Again thanks, DoN.

The dangers of letting people of one specialty comment on another :-)

What she is talking about is called a "packer" in the trade and is a commonly used device to plug wells or isolate various zones in a well.

The problem comes about with how are you going to (1) get it into the riser, and (2) how are you going to poke it down past the leak. Remembering that once you get to the leak you have a lot of well pressure to overcome. If the riser is, say 10 inch diameter and you have a well pressure of, say 7,000 PSI then total force against the inner tubes is perhaps something like 750,000 pounds of pressure to push against to get the plug in place, depending on how much of the hole the inner tube device is closing off in the riser as you maneuver it into place.

Cheers,

John B. (johnbslocombatgmaildotcom)

That's some pretty scary numbers, John.

If that is a close estimate of the pressure, do you think they will actually cap this leak - or not?

so, what do you guys think the device in the Boa Deep C ROV 2 video at the spillcam site is measuring?

The reported depth I read was 35,055 ft. for the well drilled in 4,132 ft. of water.

Water pressure, using rule of thumb for salt water, is 0.44 lbs a foot, or sea bed pressure of .44 times 4,132 = 1818 psi.

Hydrostatic pressure at the bottom of the hole is .44 times 35,055 =

15,424 psi.

According to a good friend of mine who is an offshore drilling superintendent and is getting stuff from all the drilling guys he knows, the well was completed with 7 inch casing and they were using

16 lb. per gal. mud. which indicates some pretty fancy formation pressure.

Water weighs about 8.35 lbs. so 16 lb. mud weighs 1.9 times as much as water so bottom hole pressure would be 29,305 psi.

Now, this is all based on bottom hole pressure and the pressure decreases with every foot less depth so likely that actual well pressures are nowhere that high, but it is an indication of how high the formation pressure was,

If for example, the producing formation was at 10,000 feet, mud pressure, which is used to control the pressure, would be 10,000 X .836 = 8,360 psi. Formation pressure would be somewhat lower of course.

But to answer your question, no they won't "cap the well" unless they can somehow close the BOP. What they are doing is putting a cover over the well to contain the oil and vent it up to the surface and store it.

They are drilling two (I believe) relief wells that will intersect the blown out well and then they will pump in very heavy mud and effectively fill the casing with mud all the way to the surface which will stop the well flowing.

They have a pretty good idea of what pressures were all the way down the well, from their well tests, so they will likely use a mud that is heavy enough to kill the well with the mud, say 1,000 feet below the surface and then set a "packer" to hold the mud in place and then pump the top of the well full of concrete to make a permanent plug.

That is assuming that the well is flowing through the casing. If it is flowing around the casing string because the cement job failed between the outside of the casing and the formation then they have a new set of problems. However once they kill the well thy will have time to cope with the problems.

Cheers,

John B. (johnbslocombatgmaildotcom)

I didn't see it.

Cheers,

John B. (johnbslocombatgmaildotcom)

Some of the guys over on another site have been following this, over

100 pages worth and counting. Some of them are driller types and spotted that there's still drill stem in there, apparently the BOP couldn't shear through the end couplings, but mangled it enough so it won't come out. So NO WAY is anybody going to poke anything substantial down that hole now, probably that pipe is well and truly stuck in the BOP for eternity or until the works blows out like a soda straw cover. There's also some question as to the security of the various joints in the well casing in the depths below, it's not all one contiguous and same diameter pipe. If somebody plugs the end, the whole works may come shooting out of the hole. For the same reason, adding a lot of mass to the top may aggravate things, the BOP on BOP solution probably isn't in the cards no matter what, it's not attached to solid seabed platform. Would be like sticking a 10 story building on top of a soda straw. If the casing shoots out, game over until the relief well(s) plug things, or if. That oil is at several hundred degrees, thousands of psi and isn't something to really be dabbling with. Think underwater oil volcano if the works blows out. So the BP engineers are probably going through the motions, trying to recover what oil they can without disturbing the works too much, for PR's sake and depending on the relief wells to come through for them.

See:

what's supposed to be down that hole. Apparently there's some question as to how much cement was used to seal the various sections. Comes down to corners being cut on constructing the thing. Nobody's covering themselves with glory on this one, from the Prez on down. The US gov. has been taxing oil for just such emergencies, where'd the money go?(as if I didn't know!) And BP and their contractors look like they were cutting corners to cut costs. The only thing they're really getting out of this is a crash course in how NOT to stop an underwater oil leak at those depths. And the ROV operators are getting in a lot of really good practice time.

If you've got the time, you could read through the whole thread above, lots of pics.

Stan

I do know that they had a lot or problems in that hole due to lost circulation, i.e., they were getting mud flow into the formation and that they used a light weight cement.

Here is part of an e-mail I received from a mate who is a rig superintendent on a rig off Vietnam at the moment:

This well had been giving some problems all the way down and was a big discovery. Big pressure, 16ppg+ mud weight. They ran a long string of

7" production casing - not a liner, the confusion arising from the fact that all casing strings on a floating rig are run on drill pipe and hung off on the wellhead on the sea floor, like a "liner".

They cemented this casing with lightweight cement containing nitrogen because they were having lost circulation in between the well kicking all the way down. The calculations and the execution of this kind of a cement job are complex, in order that you neither let the well flow from too little hydrostatic pressure nor break it down and lose the fluid and cement from too much hydrostatic. But you gotta believe BP had 8 or 10 of their best double and triple checking everything.

On the outside of the top joint of casing is a seal assembly - "packoff" - that sets inside the subsea wellhead and seals. This was set and tested to 10,000 psi, OK. Remember they are doing all this from the surface 5,000 feet away. The technology is fascinating, like going to the moon or fishing out the Russian sub, or killing all the fires in Kuwait in 14 months instead of 5 years. We never have had an accident like this before so hubris, the folie d'grandeur, sort of takes over. BP were the leaders in all this stretching the envelope all over the world in deep water.

This was the end of the well until testing was to begin at a later time, so a temporary "bridge plug" was run in on drill pipe to set somewhere near the top of the well below 5,000 ft. This is the second barrier, you always have to have 2, and the casing was the first one. It is not known if this was actually set or not.

At the same time they took the 16+ ppg mud out of the riser and replaced it with sea water so that they could pull the riser, lay it down, and move off. When they did this, they of course took away all the hydrostatic on the well. But this was OK, normal, since the well was plugged both on the inside with the casing and on the outside with the tested packoff. But something turned loose all of a sudden, and the conventional wisdom would be the packoff on the outside of the casing.

Cheers,

John B. (johnbslocombatgmaildotcom)

more interesting discussion here

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