use gas lift pump on BP Macondo blowout? 4

[Windward]

To capture the leaking oil and gas until it has been stopped, would a gas lift pump work? There is about 40% methane by mass in the leak. This high percentage of gas would create a very powerful gas lift.

Direct the leak -that is, after the oil/gas has left the wellhead and is in the water at the 5000 foot depth (in other words, I am not suggesting using gas lift in the well itself) - into the open bottom end of a pipe running down to the leak from a salvage vessel.

Once this flow starts moving up the pipe, the highly pressurized methane will continuously expand because the pressure above the mixture is constantly falling. This will reduce the average density of the mixture in the pipe. At steady state flow, it will be much lower than the density of the seawater outside of the pipe.

It would be a giant chimney but with a much greater driving force than if the fluids were gases only, because of the much greater densities and the much greater difference in those densities. If the average density in the pipe is 4/5 that of seawater, the driving force at the bottom of the pipe would be more than 400 psi.

The oil/gas/water mixture will exit the pipe at high velocity at the salvage vessel, perfect for separating the liquid from the gas in a cyclone.

No outside power needed, equipment far simpler and cheaper than what they have been trying.

I know that word - CLATHRATES. They will plug up the flow! But will they, with 400 psi driving it? And if they are a problem, do what they are doing with tophat and put some methanol into it, or some warm water. Not hard when we are looking at the complete destruction of marine life in the Gulf of Mexico and the consequences of that.

 

[zdas04]

bp has a toll free number. Call them. If the idea has merit they'll thank you for it. Last count they had over 4,000 ideas from the public that they were evaluating.

David

 

[Windward]

I submitted it several days ago and received their response yesterday:

"Your submission has been reviewed for its technical merits. Unfortunately, the team has determined that your idea cannot be applied under the very challenging and specific operating conditions we face. All of us on the Horizon Support Team appreciate your thoughts and efforts."

Of course they don't have time to explain why they think it wouldn't work. That is why I am asking for comments on this site.

There is some discussion of the gas lift effect on the Oil Drum today (June 4), although not in response to any of my posts there on the subject.

It is taken for granted at the Oil Drum that clathrate formation must be prevented. Therefore seawater cannot be allowed to enter the flow.

The Top Hat attempt now underway apparently does rely on gas lift to move the oil/gas. On Oil Drum there is speculation about unstable flow in the pipe leading from Top Hat to the salvage vessel due to unpredictable behavior of the methane as it expands, which requires extreme caution as the flow up the pipe is allowed to increase.

My main question is why there cannot be some seawater allowed into the flow. It seems to me that any clathrates would be swept along fast enough to prevent plugging. If some seawater could be allowed, there would be no need for a seal on Top Hat, or even a top hat. It could simply be an open pipe just above the leak, taking in the oil and gas and the minimum possible amount of seawater. All that cutting of the BOP and delay could have been avoided. The pipe could have been sent down almost as soon as the leak began.

IF the method works. Why didn't we know this already? Because the oil industry - and many others - have been allowed to regulate themselves.

 

[DrillerNic]

Well seeing as pipe freezing is an accepted way to plug flowing pipes in oil processing plants where vlaves have failed, and seeing as methane hydrates form almost instantly, and seeing as there is quite a lot of gas in the flow from the well, perhaps your assertion that "any clathrates would be swept along fast enough to prevent plugging" needs to be checked? Perhaps the well control specialists working on this have already done the calculations and found that your assertion is false? Just guessing...

There will be a gas lift effect from the methane in the flow, (but this well doesn't depend upon gas lift to flow as the reservoir pressure is more than enough to flow to surface- that's why it's blowing out!) but speaking as someone who has designed gas lift systems, the amount of gas injected into the liquid stream does have to be calculated pretty closely to stop a well from slugging. This isn't a designed system, so there will be concerns about the flow regime in the riser as they ramp up the flow up the riser.

 

[Windward]

Appreciate your comments, DrillerNic. You are way ahead of the experts on the Oil Drum in providing details and useful information on this idea.

Just from the internet, since I am not versed in this subject, one way to remove clathrates is to reduce the pressure and increase the temperature. Both of these processes occur naturally as the flow moves up the pipe at the Macondo blowout.

In the arrangement I am suggesting, to get the flow started and avoid clathrate plugging until it is no longer possible (ie., when the flow is further up the pipe, but then I am assuming this would be the case), warm water and methanol injection might be enough. I believe they have done both at Macondo, but details of application, temperature, flow etc, are not available so far as I know. In any case, their object is to avoid seawater influx at all costs, and the warm water and methanol is not being used in any proposed system similar to the one I am suggesting.

If methanol injection is expensive, in this case the expense would be negligible compared to the damage that could be avoided.

I realize that the current Top Hat is using pressure from the well and not relying on gas lift, although there must be considerable gas lift occurring also. My approach is to let the well leak and avoid stressing the BOP and piping, then collect the leak after it is in the water.

Hope you can comment further.

 

[Windward]

I am posting this before seeing any further replies.

Regarding BP's expertise in clathrate formation, I wonder what the justification was for the original 100 ton containment dome. It plugged with clathrates almost immediately. If BP knew this would happen, then the effort was for public relations only.

If they weren't sure that it would happen, and thought that it was worth a try, maybe they don't know as much about clathrates as we might suppose. In that case, maybe my suggestion was dismissed for no good reason.

Possibly it was not even examined, and the reply I received was a standard form sent by email robot. Experience tends to erode one's trusting nature.

 

[waross]

The expanding methane in the riser to the surface has the effect of reducing the net flow.
With a few thousand PSI rising to possibly 15,000 PSI if the leak is restricted, and the specific gravity of being less than water anyway, why do we want a gas lift? I we use air for the gas lift we can have the excitment of an explosive mixture instead of a flamable gas reaching the flare stack.



Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[whammett]

Ok. Currently BP is deliberating installing a larged cap to try and draw more of the oil from the cut riser. They are currently capturing roughly 623,000 US gal per day of oil(based on yesterday's take of oil). There is roughly 20,000 bbl of oil leaking out per day(current estimate, gathered via CNN), which is 840,000 US gal. However, the are unsure whether to attempt this because the down time it would take to remove the existing cap and install the new one, allowing oil to flow freel again, might be more than collecting an extra proposed 50,000 to 100,000 US gal per day is worth in the long run.
Two days are proposed to install the new cap. Thats an estimated 840,000*2= 1.68 mil gallons of oil being leaked in 2 days. Is it worth the extra 50-100,000 gallons per day collected?
IMO, if whats happening now is working, tweak the current idea, but its pointless trying something completely different unless the cap hits a "snag", or there is a 99% chance of success. Good luck with the latter.

"Scientists dream about doing great things. Engineers do them." -James Michener

 

[Windward]

waross, not sure if you were thinking that I was proposing air as an alternative gas for the lift. I am not, for the obvious reason you mention.

Why am I proposing gas lift? Because it would take the strain off of the BOP and well piping/casing. There is tremendous uncertainty about the condition of this equipment. That is the main reason they are going so slowly in raising the flow in the current top hat, and nearly half of the oil is still leaking with this arrangement.

If the leak is allowed to enter the seawater and could be collected as I suggest, then there is no connection to the wellhead and no need to go through the tremendous and time consuming effort of trying to attach some kind of collector to the wellhead. The pressure and other conditions in the seawater at the point of the leak are exactly known and calculations would be on a reliable basis.

If the method works, it might capture all of the oil and gas along with some seawater. It could be used at future blowouts of this kind, tested and ready to go. If it works, the oil companies ought to be required to have the equipment in place at all times, in case of a blowout. We have learned that no such method is available yet.

 

[whammett]

"nearly half of the oil is still leaking with this arrangement"

Not true, check my numbers.

And also, they quit using the term top hat with the last 2 failed attempts. This is just a cap, with no flat bottom. This is just me being picky. To all their own.
___ ___
| | instead of _| |_

With that being said, I agree with your statement, if done correctly it could be very beneficial.

"Scientists dream about doing great things. Engineers do them." -James Michener

 

[Windward]

whammett, good information in your posts. If I had known that they are capturing 623,000 and leaking 840,000, I would have said "more than half" is leaking.

Can't figure out what "instead of" means in your second post.

Top hat may be old hat, but I believe we know what I meant by it. Are they calling it a cap now?

 

[whammett]

Yes, they are referring to it as a cap now. Sorry for the crude image, that was my feeble attempt at trying to relate the diffreneces between the top hats and the new "cap" without actualy sketching and uploading a drawing. The first representing the cap, the second representing what they refered to the first two as "top hats".

"Scientists dream about doing great things. Engineers do them." -James Michener

 

[waross]

As I understand the situation, the BOP is partially closed and creating a large pressure drop. Large enough that capturing all the oil will not cause issues with the BOP.
As I understand it, they are concerned that the casing and cementing have been compromized. If they stop the leak by closing the BOP completely, the concern is that the cementing or the casing may fail from the increased back pressure.
A subsea casing rupture or a casing lift that also lifts the BOP may cause subsurface leaks so that instead of the leaking oil escaping from one pipe where there is a chance of collecting most of it, they may have oil seeping up through the sea floor over a very wide area. Worse, this oil flow may not be affected or reduced by the partially closed BOP as it is now.


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[waross]

Have you ever had a flatb tire and found that your spare was flat also. Have you ever started a trip into an outof the way place with bad roads and little help mavalable knowing that your spare was flat and embarked with no attempt to fgix the spare first?

There is technology available to control oil well kicks and blow-outs. It has probably been in use for over 50 years.
Called BLOW OUT PREVENTERS.
Most operators will not drill if the BOP is in bad order.
Let's look at the sequence of events.
1> The BOP was damaged and not repaired about a month earlier.
2> They knew that they had a hydraulic leak in the BOP but continued working
3> They knew that the pressure was down in the BOP hydraulic system and continued working.
4> When the cementing crew came onboard, they did not know and were not told that the BOP was in bad order.
5>A bad decision was made to replace the drilling mud with sea water to save money.
6> The well kicked. The kick may not have happened or may have been less severe had the mud been in place providing almost twice the back pressure of the sea water.
7> The cementing crew saw the kick coming and reacted in the proper manner to control it. They activated the annular device to contain the kick.
There was no annular device. It had been destroyed and not replaced.
8> There is a good chance that the activation of the missing annular wasted more hydraulic fluid and pressure.
8> The shears were eventually deployed. They did not complete their stroke. Possibly due to the depleted hydraulic oil supply or due to the reduced reserve operating pressure. Possibly both. Possibly the BOP was under engineered for the application.
bp can't handle the existing technology. How much more technology do you want to see them mess up??
This is not a technology frailure. There is enough techology and enough people that know how to use it safely. Just not in the bp chain of command.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Windward]

First, let me say that I wish I had never heard of Windows Vista.

waross, roger that, BP has committed many sins with this job and heretofore. As someone said on the Oil Drum, he didn't want to mention any names but a certain oil company seems to be experiencing the laws of karma.

Good clarification about the BOP, it is the underground piping they are most worried about. However, I have read that there is a significant failure rate with BOPs, something like 25%, even when they are not mistreated as BP apparently did this one. I would provide some kind of a link for this statement, but am having internet connection trouble. It is a wonder I got back to this site.

On the Macondo BOP, there is speculation that the shears happened to be over a joint in the piping. Shears are not designed to cut through a coupling, so it might not have helped if the hydraulics had been working. In response to this blowout, there is a proposal to require two sets of shears on the BOP, four feet apart, so that at least one of them will miss the coupling.

 

[waross]

I understood that there are at least two sets of shears for that eventuality.
bp's public relations to the contrary this is not a "One in a million" occurance. Kicks are common in some formations and areas and are routinely contained. What is more unlikely is the cavalier way that standard safety procedures were violated.
If the shears hit a joint, that would be less fluid and pressure for the second set of shears to close.
There are also sections that are designed to seal around the drill pipe.
The annular seal is the first response. I understand t6hat there are designs that will seal around a drill pipe, around a coupling, or seal a casing with no drill pipe in place.
But what it will not do is seal a well when it is in pieces on the mud screens.
The gate seal that has a profile and seals to close around a drill pipe is the second response.
Shearing the drill pipe is the last response.


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Windward]

Well, waross, looks like its you and me now. What do you think of the gas lift idea I proposed to start this thread? It all comes down to clathrate formation. Is it an insoluble problem for this method?

As I mentioned above, if BP knew that clathrates would always plug up the pipe in these conditions no matter what, why did they try the first containment dome? If it was just PR to gain a little time, then the PR failed along with the dome.

If they thought that the dome might work, then either they are complete fools regarding clathrates, or they had some reason to be believe that the plugging could be prevented.
If so, then there should be a way to implement my idea.

As I mentioned in an earlier post, the BOP and well piping are left alone when using a separate pipe for the gas lift, and the big worries about damaging the well by attaching something to it are over.

They can collect all of the oil and gas after it has leaked until they can stop the leak. Not only that, the method would work in similar situations, which are bound to happen.

 

[waross]

Hi Windward.
As I understand it, this started with a "Kick" and as I undestand that, a kick is a sudden unintended gas lift.
The challenge is to collect as much product as possible without including water in the mix. As I understand the dynamics, conditions are very good for the formation of clathrates and I suspect that the cooling caused by the expanding gas may lead to ice buildups as a further problem. I believe that at this point, it may be as well to leave well enough alone.
Perhaps the easiest way to effect a "Gas lift" would be to simply heat the cap and encourage the gas already present to expand and start the lift.
Trying to change the cap now to achieve a better seal is probably the most effective way to deal with the problem. Unfortunately the increased discharge during a change and the possibility of failure may result in a net loss in collection at the end of the month.
Once the oil has escaped, the collection difficulty increases enormously.
Your position and focus is to collect the escaping oil. My position is that the best solution is to collect as much as possible before it escapes.
Everyones problem is the Peter Principal as it applies to bp culture. I am sure that there are a lot of very good engineers working for bp. Unfortunately, when promotion time comes, the best engineers are often left doing the real work while the less productive are promoted. It ain't fair but that's life.
I may be wrong. There is so much information not available to the general public that engineering a solution is almost impossible.
What is the well pressure?
bp won't say.
What volume is leaking?
bp has prevented this from being determined. There was a team of scientists on route to measure the leakage rate with proven technology. They were turned around and the big lie started that measuring the rate of leakage was impossible.
Peter Principal and culture may have been responsible for this mess. (How do you spell hubris)
The engineers trying to solve this have the triple anchors of Peter Principal, culture and now, goverment interference. I think that they are doing as well as can be expected.


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[junkcatcher]

Seems to me, as waross said, we don't have the numbers from BP and others; but they do have the numbers.

From the symptoms, I can only guess that the flow to the Discoverer Enterprise is flow-limited, choked, somehow. Has BP done the flow study to determine how much oil and gas the flowline can handle? What about the flare line? Is it operating at its sonic flow limit?

Seems to me that in order to properly design the flow system from the BOP Cap to the ship, BP would have first done an open-flow study of the well to realistically know what is the amount of oil and gas that is probably coming up from below. That would establish the required capacity of the Cap and its connecting line to the ship.

Surely BP did this. Surely BP didn't create a problem by designing a line and onboard flare and separator system that didn't have that capacity.

Are we missing something here?

 

[Windward]

Many good points there, waross. Corporate culture and the unstoppable demand for oil has resulted in one tremendous disaster. Just one aspect of it is that the people who are going to suffer the most will never get anything close to the relief they deserve, and they will have to wait decades for it, if they live that long.

junkcatcher, as I understand it from the Oil Drum, the cap and riser are delivering more flow than the processing equipment can handle, so yes, they apparently made some mistakes. And the captured oil flow is still less than the leaking oil flow. The way things are going, the reputation of engineers is going to be reduced to the lawyer level.

Also on Oil Drum, we are reminded that the work on the recovery vessels is very dangerous, especially because of the unpredictable flow rate and the constantly changing fractions of oil and gas. oceannomad said: "There is an old oilfield adage which I hold dear - Courage is proportional to the square of the distance away from the wellbore."