British Petroleum sucks... except when they have to !

[Externet]

British petroleum sucks... except when they have to !

 

Where is the mystery in installing a sucking pump at the surface to suck the petroleum from the leaking pipe joint so it sucks seawater in instead of leaking petroleum out ?

[Cap'n Refsmmat]

I suppose it's difficult when there's about 20 gallons per second flowing out of the wellhead, that you have to pump 5,000 feet vertically. You're limited by the height -- if the pressure at the bottom isn't high enough, it simply won't push the oil up, and a pump at the top is limited.

 

For example, if the pressure at the bottom and top were both atmospheric, and your pump lowered the top to a vacuum, you'd only get 14.7psi acting on the fluid at the bottom, no matter how much harder the pump worked. It can't pump any harder. Similarly, pumps on the drill ships are limited by the pressure at the bottom.

 

The only way to get over that is to put a pump on the seabed, which is hard.

[Externet]

Thanks.

If the petroleum well flows freely at -say 20 gal/second; installing a 40 gal/second pump at the surface (not above the surface) will not counteract the leak ?

[Cap'n Refsmmat]

Let me give an example. Let's suppose we have a twenty-centimeter diameter pipe that just has water in it, density 1000kg/m³. At the bottom, the pressure is 100kPa, about atmospheric pressure.

 

The volume of that pipe is [math]0.01 \pi h[/math], where h is how tall it is and the answer is in meters. (0.01 is 0.1^2, the radius squared.) The mass would be 1000 times that, [math]10 \pi h[/math].

 

Suppose we pump all the air out of the top of the pipe, so there's a vacuum. The pressure difference is 100kPa.

 

The force on the water column at the bottom will be [math]100 \mbox{ kPa} \times \pi r^2[/math], or 3141 Newtons. 3141 Newtons divided by g is 320kg, which is how much mass that force could hold up.

 

So we let [math]320 = 10 \pi h[/math], solve for h, and get about 10m.

 

For that pressure difference, a perfect pump could only pump water a maximum of 10m, no more. It's dependent on the pressure difference -- no pump can make the top of the pipe less than 0 Pascals, so you cannot increase that pressure difference without a pump at the bottom of the pipe.

 

Now, in the oil well 5,000 feet under the ocean, the pressure at the bottom is much higher, but the principle is the same.

[ydoaPs]

Surely the natural separation due to density differences could be utilized to aide the pumping effort. If the oil is coming to the surface anyway, why not pump from there?

 

I actually thought this was going on.

[Cap'n Refsmmat]

A lot of it doesn't seem to be coming to the surface, as is evidenced by the large underwater plumes of oil that have been discovered.

 

I suppose if they could get a perfect seal around the leaking pipe, the pressure from beneath would push the oil straight up into the drill ship. But getting a perfect seal is hard.

Edited June 11, 2010 by Cap'n Refsmmat

[ydoaPs]

A lot of it doesn't seem to be coming to the surface, as is evidenced by the large underwater plumes of oil that have been discovered.

 

Yeah, I should have anticipated the water becoming emulsified in the saltwater.

[Externet]

Thanks again.

Something does not click at all

 

Allow me to put this in other form:

 

A one mile long vertical pipe into the ocean, with open bottom end, open top at the surface.

To me, any pump placed in the pipe at the surface will suck the pipe column contents as effortlessly as if there was no pipe and sucking from the sea surface. (Well, a tiny difference by flow resistance)

 

If instead, at the bottom end, petroleum at whatever pressure is rushing upwards, it would be even easier to pump !

 

Without disagreing with your figures. It just does not make sense.

 

I worked several years constructing shrimp farms, intalled several 30" pumps on 300HP with brutal flow figures I cannot recall right now; the impeller was about 2 metres under the surface in high tide and perhaps a few centimetres above in low tides. The pumping height was about 5 metres, but hell they delivered a brutal flow without any help pushing water into the inlet!

 

Edited - added : Like these---> http://www.deltadelfini.com/eng/products/axial_mixed.html

This is the setup : http://www.deltadelfini.com/eng/products/around.html

Edited June 11, 2010 by Externet

[Mr Skeptic]

For that pressure difference, a perfect pump could only pump water a maximum of 10m, no more. It's dependent on the pressure difference -- no pump can make the top of the pipe less than 0 Pascals, so you cannot increase that pressure difference without a pump at the bottom of the pipe.

 

Now, in the oil well 5,000 feet under the ocean, the pressure at the bottom is much higher, but the principle is the same.

 

Not really, it's a different principle. You can't pump more than 10 m above the surface of the water. However, because the pipe would be underwater, the pressure difference will just get transferred down rather than counteracted by gravity. In fact, if you assume that the density of the fluid in your pipe is lower than the density of the seawater, it will flow upward even without a pump.

[Cap'n Refsmmat]

Not really, it's a different principle. You can't pump more than 10 m above the surface of the water. However, because the pipe would be underwater, the pressure difference will just get transferred down rather than counteracted by gravity.

Could you clarify?

 

In fact, if you assume that the density of the fluid in your pipe is lower than the density of the seawater, it will flow upward even without a pump.

Right, although if you have a perfect seal at the bottom, I don't think that would happen.

[Externet]

Cap'n : Perhaps you are thinking on a pump with an impeller <10m above the fluid surface, were you have partial vacuum primed column.

 

If pumping was limited to 10 metres, how does the Empire State gets water supply at its 101 floor ?

[Cap'n Refsmmat]

They pump from the bottom, not the top. You push the water up instead of relying on the pressure from the top.

 

Hard to put a pump 5,000 feet underwater.

[Externet]

:confused: Sorry, I do not understand your rationale.

 

The sea surface would be the "bottom" of the "pushing" pumping they have to implement to suck seawater into the leaky joint below !

 

As if there was a swimming pool at the Empire state floor zero. You place the pump there, not at floor 101 !

Edited June 11, 2010 by Externet

[Cap'n Refsmmat]

No, the surface of the ocean is the top of the pipe, and the leaking well is at the bottom. You'd place the pump at the bottom for the best results.

[Mr Skeptic]

Could you clarify?

 

Sure. Pressure contribution from fluids is [math]P = \rho g h[/math]. A pump produces a pressure difference via a different method of course, but it doesn't really matter which, just that it creates one. Anyhow, the fluid will flow from an area of higher pressure to an area of lower pressure. The atmospheric pressure of course should not be forgotten.

 

So, you add up all the contributions to pressure and see what it adds up to. First the atmospheric pressure, then add on the pressure contributions of the respective fluids. If the outer fluid is air and the inner fluid is water, then the pressure contribution inside the pipe adds up to a lot more than the pressure contribution from outside the pipe. Given enough height, the difference will eventually equal the the pressure contribution from the pump. At that point, the pump cannot pump.

 

However, if the outside fluid is more dense than air, it would make more of a contribution. Or, if you simply have warmer stuff that is less dense, it will rise. It's basically the same stuff as buoyancy.

 

Right, although if you have a perfect seal at the bottom, I don't think that would happen.

 

Yeah, I'm not sure how that would work. If done poorly, the bottom of the pipe could get crushed.

[padren]

Why not put it all in place as if you were going to pump it, then fail and say "oh well, at least it's not leaking into the ocean" while you take the time to get the relief well going?

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The only way to get over that is to put a pump on the seabed, which is hard.

 

Don't they use a double-hull pipe, and push something heavier down through one hull from the top, to displace the oil to create the rising pressure?

[Cap'n Refsmmat]

Don't they use a double-hull pipe, and push something heavier down through one hull from the top, to displace the oil to create the rising pressure?

 

What I understand is that the double-hull pipe has hot water in the outer hull, being pumped down to prevent any methane hydrates or ice from forming in the cap in clogging it. I don't know if it's also pushing the oil back up.

[ydoaPs]

Wouldn't a positive displacement pump work better in this case then since it pumps the same amount of fluid per stroke regardless of pressure on either side of the pump?

 

For those not familiar with the distinction, impeller pumps are like fans for liquids; their capacity depends on the pressures. Positive displacement pumps are like a syringe(in fact, you can make a simple one with a syringe type plunger assembly and two check valves) and pump the same volume of water no matter what.

[JohnB]

Possibly a silly question, but why do you need a powerful pump?

 

Since the oil is coming out under presuure and is generally lighter than water, it's trying to rise anyway. If you placed a large inverted funnel over the leak with a pipe leading to the surface, wouldn't the oil come up the pipe?

 

Granted the pressure might not be enough to displace all the water in the pipe, but that could be pumped out allowing the oil to rise. The more water pumped out of the top of the pipe, the more the oil will push up from underneath. If you are pumping out the pipe, then the pressure inside the pipe will be lower than outside the pipe and the oil would preferentially stay inside and rise.

 

After that you just pump the oil into tankers at the surface.

 

It's not a fix, but a stop gap while you get the equipment in place to plug the leak.

 

Or am I missing something?

[Realitycheck]

With the cabling and electricity required to power these robots, a good pump certainly seems doable. Just build a new cap with the pump on the bottom.

 

What I don't understand is where they are coming up with these new flow-rate numbers. Surely, they are trying to say that it would flow 40,000 barrels a day if it were not capped. They are capturing 15,000 barrels a day pretty consistently. Looking at the thing, it is leaking, maybe a gallon(or two?) per second, max? Of course, this is too much, but that equates to 2,000 barrels a day additional.

 

How is it that the flow through the cracks (with a mile of water beating down on it at that) could so greatly exceed the unimpeded flow through the pipe in water?

Edited June 16, 2010 by agentchange

[Zolar V]

The burst pipe was leaking around 400,000 barrels of oil a day. that was reduced to 200,00 barrels of oil a day. so my question is, do we even need a pump? if we would have lowered a pipe that encompassed the base of the leak, the natural pressure of the oil would have been enough to push it to the top. basically were just using the same principle that every oil rig uses. then the question wouldn't be what do we do with the leak it becomes we need to have 24/7 transfer of oil from the pipe to the refineries.

 

imo the only reasons why we did it the way we did was money. they tried to do the cheapest thing possible, also i suppose having a ceo decide isn't the best decision being that he is probably not knowledgeable about anything that would come anywhere near this problem

[Cap'n Refsmmat]

They lowered a cap that covered the base of the leak. It got clogged with methane hydrates and crap. Hence this method.

[Realitycheck]

Yes, here they point out that the revised flow rate is uncontrolled. The highest flow rate ever recorded was about 120,000 bpd back in the age of the gusher.

 

http://en.wikipedia.org/wiki/Blowout_(well_drilling)

 

Somewhere else I read that the typical flow rate for this type of well is about the same 15,000.

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Consecutive posts merged Edited June 16, 2010 by agentchange
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[Externet]

As far as I understand, the initial damaged riser pipe did not get a clean cut because they used the wrong saw, positioned at the wrong place and they ended snipping it instead leaving a irregular cut; they never used a thick silicone covered new pipe with conical fit as to force mate and seal the joint; and the 21" leaking well outlet pipe got a 4" new riser 'attached' to recover what they are recovering until they gamble the next action.

 

http://bp.concerts.com/gom/riser_cut_explained.htm

 

http://bp.concerts.com/gom/successful_install_lmrp_cap_060510.htm

 

http://bp.concerts.com/gom/enterprisetopcap060610.htm

Edited June 17, 2010 by Externet