PSI?
Does anyone have a handle on pounds per square inch of pressure of the flow of oil (mud not heavy enough?) against the pounds per square of sea bed pressure, and then subsequent impact as the flow encounters considerably less pressure the closer to the surface the flow gets?
Update from comments in Oil Drum today:
Reservior quality oil is API 35 (right on edge between light & medium quality crude, few asphaltenes, which make the “best”, longest lasting tar balls) with lots of natural gas (3,000 GOS, 10,000 GOS is considered a gas well). The oil emulsifies with water easily, much better than most crude oils.
The reservoir pressure is 13,000 psi. (Temperature only 180 F from one report, unusually cold). 4 weeks ago the pressure was reported as 8,000 to 9,000 psi entering the BOP and just seawater pressure (@ 2,200 psi) + 400 psi exiting the BOP. This implies much more than just a frictional drop up 13,000′ of drill string, but some obstruction as well.
Since then sand entrained with the gas and oil has eroded the BOP and BP has stated that new observations of BOP pressures were “surprisingly lower” but gave no numerical data. OTOH, downhole, it is normal for wild wells to pull rocks as well as sand into the bore and clog things up.
However, this specific well has cased for production (later), which is designed to prevent being clogged up by produced rock and sand.
My GUESS is that the pressure drop downhole in the well bore is greater and drop across the BOP lower since Thad Allen leaked the pressure #s.
This also implies that the clogging the holes spewing that we can see does nothing, since they represent just a 400 psi drop. Raise that to 1,000 psi by reducing the size and that will feed back SLIGHTLY to the other, larger pressure drops.
One interesting observation is that the natural gas is dissolved in a super-critical fluid in the reservoir and begins to comes out of solution as it transits the BOP. Expanding gas is quite a force.
A major issue is inertia. Roughly 2 ft2 column coming up 13,000′ and a few feet/sec is quite a battering ram. Beyond that is a good sized reservoir. It has been sitting still for the last few million years, and now it begins to flow towards this new hole. Given the size (perhaps 100 million barrels) it will take months for all the oil to start flowing evenly towards the well. But that is another source of inertia which will continue to grow over time.
I am confused (me too) as to whether the Top Kill/Junk Shot is injecting mud & debris where the pressure once was seawater (@ 2,200 psi) + 400 psi or 8,000 to 9,000 psi.
I hope this helps a bit. I personally have very little hope for anything except the relief wells.
Dan
at 5000 ft water pressure would be about 2000 psi.
don’t know what the pressure of the gas is, but it would decrease as it rises… more or less exactly balancing the water pressure and expanding as bubbles. don’t know what happens to the liquid oil. suspect it just disperses by something like brownian motion. oil is much lighter than water. mud is much heavier. imagine they use mud as filler with the concrete to make it dense enough, and cheap enough, to have a chance of plugging the hole. but i really know nothing about this and only offer this as a place to start.
When the oil has escaped the hole at the sea bed, the pressures have been equalized. Any subsequent flow of that fluid is dictated by the local currents and the buoyancy of the fluid.
Mud has to not only be dense enough to overcome the pressure in the well bore but has to be injected at a high enough pressure to make it into the hole and take effect.
Think of a garden hose shooting water straight up. If you try to drop steel BB’s in it to stop the flow, depending on how fast the water is escaping, the BB’s will either sink to the bottom and clog the hose or be pushed aside by the water. If they are being pushed aside, you need to inject the BB’s with enough velocity to overcome the resistance of the flow.
Thanks MacD.
Okay. But the resevoir at the end of the pipe and hose is at one atmosphere or equal to the pressure to the other end of escaping water in the example. Is there a difference when the psi is considerably more at the resevoir end? How are psi, volume, velocity related, and the ‘hose’ which restricts flow related?
Liguids are not compressable. Volume is the same regardless
of pressure. The differential in pressures at sea bed (about 150 atmospheres or 2000 lbs/ sq in) and what ever pressure the petroleum reservoir is under (there were reports of “kicks” of 3600 psi which I assume mean “spikes” and refer to absolute pressures indicating differentials on the order of 1600psi) is responsible for the movement of petroleum to the sea bed. Velocity will depend on viscosity and “friction”. The differential in those pressures is equalized within feet of where it is released (hole in pipe). As stated by macD. And it surfaces at rates based on the differential in density (specific gravity) or again as macD says bouyancy (the inverse of density).
Gasses are compressable and volume is dependent on pressure & temperature. See boyle’s law.
http://en.m.wikipedia.org/wiki/Boyle’s_law?wasRedirected=true
Liguids are not compressable. Volume is the same regardless
of pressure. The differential in pressures at sea bed (about 150 atmospheres or 2000 lbs/ sq in) and what ever pressure the petroleum reservoir is under (there were reports of “kicks” of 3600 psi which I assume mean “spikes” and refer to absolute pressures indicating differentials on the order of 1600psi) is responsible for the movement of petroleum to the sea bed. Velocity will depend on viscosity and “friction”. The differential in those pressures is equalized within feet of where it is released (hole in pipe). As stated by macD. And it surfaces at rates based on the differential in density (specific gravity) or again as macD says bouyancy (the inverse of density).
Gasses are compressable and volume is dependent on pressure & temperature. See boyle’s law.
http://en.m.wikipedia.org/wiki/Boyle’s_law?wasRedirected=true
Liguids are not compressable. Volume is the same regardless
of pressure. The differential in pressures at sea bed (about 150 atmospheres or 2000 lbs/ sq in) and what ever pressure the petroleum reservoir is under (there were reports of “kicks” of 3600 psi which I assume mean “spikes” and refer to absolute pressures indicating differentials on the order of 1600psi) is responsible for the movement of petroleum to the sea bed. Velocity will depend on viscosity and “friction”. The differential in those pressures is equalized within feet of where it is released (hole in pipe). As stated by macD. And it surfaces at rates based on the differential in density (specific gravity) or again as macD says bouyancy (the inverse of density).
Gasses are compressable and volume is dependent on pressure & temperature. See boyle’s law.
http://en.m.wikipedia.org/wiki/Boyle’s_law?wasRedirected=true
Rdan,
I’m not quite sure what you are saying in your first sentence, but let me try to take a stab in simple terms.
In general, greater pressure differential means greater volume and velocity at the opening. The smaller the opening the smaller the volume and velocity. There are limits to these numbers.
As MarcoPolo points out frictional forces in the “hose” or well bore (which depends on its length) as well as the viscosity of the fluid are important considerations to get actual numbers.
If you want me to give you generalized equations so you can see the mathematical relationships, well, I’ll have to go back to my fluid dynamics books to be sure of the accuracy. Sounds like work on a Memorial Day weekend. 🙂
Dan
one point they didn’t make clear. if you have a five thousand ft pipe with concrete in it, the pressure at the top may be one atmosphere (14 psi, but at the bottom it is more like 5000 psi.
there are issues, as you may have noticed, when you put your thumb over the end of the hose it sprays farther. my guess is that the psi in the hose is “potential” and is not realized as long as a large volume is coming out the end at essentially air pressure. but when you restrict the opening, the pressure inside the hose has a chance to build up to whatever pressure the water is under where it enters the hose, plus whatever “head” is added by the height differential. i doubt these niceties have much to do with pumping concrete to the bottom of the ocean.
a real engineer could explain this. but i did meet one, with a masters degree in hydrology, who thought the fire hose pulled the firemen toward the fire because of friction of the water. another non partisan expert.
The complexity of the “leak” is, I think, being over looked. WQe keep hearing that the plan is to plug the leak, but when you see the televised image of the leak you notice that there are several leaks along what appears to be the bent pipe coming out of the so-called blow out preventer. That’s not clear. This page of diagrams from the NY Times is useful in understanding the full complexity of the problem.
http://www.nytimes.com/interactive/2010/05/25/us/20100525-topkill-diagram.html
Note that there is a bent pipe at the top of the apparatus and that the apparatus is described as 40 ft of multiple pipes. The next plan, and what seems like it should have been the first plan, is the cut off the bent pipe. I may be wrong, but it seems that the bent pipe is now being described as the source of the leak(s). What I wonder about is how on Earth did anu one expdect to “cap” the 40 ft structure of the blow out preventer? And why not cut the entire mechanism at the bottom where the main pipe exits the sea floor. What isn’t clear is whther there is oil leaking from the many pipes of the preventer or just the bent pipe at the top. What is clear is that it seems as though the Three Stooges have been called in to plan the “repair.” The linked page makes it pretty clear that the first two efforts were a “pipe dream”
of a repair. Forgive the pun.
jack
well, i didn’t know the details but it always seemed to me that a pipe slipped OVER the broken pipe would allow the oil to rise to the surface (it’s lighter than water) and get put into ships just like it’s spozed to be, and then the oil wouldn’t spread into the water. but i didn’t say nothin on accounta i don’t know nothin.
Watch the videos of the leak at the bottom. You can clearly see several blooms coming up from (?) what I think is the bent over pipe leading out of the blow out preventer. Keep in mind that the pipe, according to the diagrams, is a 21″ pipe. If the oil is escaping from the section immediately after the bend from the preventer it would be unreasonable to expect to be able to “cap” it in some way. The neew plan, if I understand the Times articel, is to cut the bent pipe just above the preventer apparatus with a diamond edged blade. Then with a clean section of pipe emerging from the preventer, to place a new pipe over that and allow the escaping oil to then be directed to tankers on the serface, I think.
I assume that there are no leaks in the preventer pipes. Otherwise how does caping a single pipe at the top solve the problem? I don’t understand why this new plan wasn’t the first plan.
jack
i haven’t seen the pictures, and i won’t. but a bell or something big enough to go over whatever is there and set on the bottom, or at least lower than the lowest leak, with a pipe at the top leading to the surface ought to conduct the oil to the surface because the oil is going to rise compared to the water, and if confined is not going to spread out all over the gulf. now those guys are at least as smart as me, so i don’t know why they didn’t do that in the first place.
Apparently the first plan to place some form of a cap over the entire blow out preventer apparatus did not work out because of the formation of some blockage within the open space of the bell like cap. Something to do with the accumulation of ice within the cap’s open space which then would block the oil from going up through an opening at the top. The new plan, if I understand it correctly, uses a smaller cap which is to be heated in some manner to prevent ice formation.
What one has to wonder is why did no one foresee such problems with potential corrective procedures before the development of the well to begin with? How do you engineer a deep water oil rig without knowing the potential difficulties that might arise when dealing with any potential disaster? Is deep water drilling so “fail safe” in the eyes of the oil industry? Or, are the people involved just so many assholes? No, I’m not referring to the engineers so much as the decision makers. Though one has to wonder where were the voices of caution to begin with? Assuming that oil is an essential product, why are such a bunch of screw ups involved at high levels of production? All we keep reading about is how unexpected this whole scenario is and was. A well head a mile deep under the sea and such a disaster was unexpected? I don’t think so. The unexpected part is that there is no good response plan that was in place before the entire enterprise got under way. I suppose the answer is in the profit statement for BP: last Q 2009, 4.29Billion; first Q 2010, 6.08Billion. At that rate BP can just buy the gulf coast states and write the entire thing off as a business expense.
jack
remember the challenger.
the engineers knew all along what had happened, but the only way they could tell the world was to lead their old professor Feynman to discover it for himself.
i don’t imagine BP is much different than the place i worked. a few bottom level engineers know what is going on… most are just drones… but they can’t tell even their immediate bosses who don’t want to hear anything that they could be held liable for if they knew about it.
i am guessing here, but aside from the possibliity that some things really were not “expected,” there is strong pressure to DO the job and make the money and keep your fingers crossed so tight you shut off circulation to your brain.
you can read the letters even here at AB. some people are just bulls. they charge ahead in spite of the risks. the fact is we need such bulls. the other fact is we need to find a way to keep them out of our china shops.
doesn’t help that most of us would rather die than drive an underpowered car.
U.S. Opens Criminal Inquiry Into Oil Spill
http://www.nytimes.com/2010/06/02/us/02spill.html?src=me&ref=us
Can you imagine? Now they’re going to investigate the possibility of any criminal activity as it may relate to the Gulf spill. How do you prosecute a corporation for operating under license to the federal government? It’s a great ploy. It takes the heat of the focus off of the event and turns attention to something that can’t exist. Holder will report back in two months or so and announce that though there had been many mis-steps along the way there was no actual criminal culpability on the part of any of the participants in this great and sad farce.
for every ft of water = 5lbs psi
and why does that live cam look like its looped they need to get a drilling ship and run a smaller drilling pipe into it about 500 ft deeper and have the pipe filled with plastic like c4 or centex it might work better then tring to save it for bp to cause more damage