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.

 

[whammett]

Sloan, E. D. Clathrate Hydrates of Natural Gases. New York: Marcel
Dekker Inc., 1990.

An old book, but you can probably find some things in there to support your argument Windward.

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

 

[Windward]

Thanks for that reference whammet, sounds like it is just what I need as I continue to develop the idea.

 

[DrillerNic]

Warross, lets look at your ponins, one by one....
1> The BOP was damaged and not repaired about a month earlier.
If this is teh suspencted damaged thte annular preventer, don't forget there are two annular preventers on a 15k BOP stack, (like the Deepwater Horizon had), so there's spare annular. And annular preventers are designed to cope with pipe being stripped through them. So maybe there was some damage to the elements on one of the annular preventers, but perhaps the rig crew had no reason to believe the annular preventer was compromised, and there's a spare one anyway?

2> They knew that they had a hydraulic leak in the BOP but continued working

Again, risk management- how big a leak? Did it compromise the functioning of the entire BOP stack or one of the invidiual preventers? As subsea hydraulic control systems vent to sea anyway when a preventer functions, the leak was probably not throught important

3> They knew that the pressure was down in the BOP hydraulic system and continued working.

Again, it's not a sealed system- it vents to sea. Provided sufficent pressure could be supplied from the surface accumulators and koomey unit pumps, perhaps it wasn't seen as an issue?

4> When the cementing crew came onboard, they did not know and were not told that the BOP was in bad order.

I fail to see why the cementers should be told this. I've never ever had a cementer ask about the condition of the BOP when they come to cement my wells

5>A bad decision was made to replace the drilling mud with sea water to save money.

No, no no no.
The riser was displaced to seawater in order to deliberately reduce the pressure inside the casing to below the reservoir pressure to do an inflow pressure test on the casing. At this point the casing was set & cemented and had had two sucessful positive pressure tests, so the casing appeared to be in good shape. I don't know the exact method of the inflow test, and possibly BP could have done it another way (close the BOP to isolate the riser & displace just the choke & kill lines to seawater?) but the principle of doing an inflow test on production casing is accepted.

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.

Currently one of the ideas about the source of gas is a gas bubble formed behind the 9-5/8" x 7" production casing during the cementing operations, and the (pressure tested) casing hanger seal let go during the inflow test. If this is so, then the failure could have occured a couple of days later (they were in the process of suspending the well ready to go home), when teh riser would be displaced to seawater to recover it to surface. And in that scenario, there would have been no comminication with the BOP at all....


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.

I think you mean the driller.... I wouldn't expect the cementers to be anywhere near the BOP control panel. And perhaps the damaged annular preventer failed. But there's another backup annular preventer. And two pipe rams, designed to seal around the pipe. And a blind/ shear ram. why did all of the BOP preventers fail to close fully?

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.

Or possibly because they didn't have time to space out to ensure there wasn't a tool joint across the shears? No shear ram anywhere an cut tool joints.....



There are lot of unknowns about this disaster.... why did the deadman switch fail, for example. But so far, we don't really know much at all, so I'm prepared to wait until the inquiry reports before blaming people and shouting about short cuts.

 

[waross]

The apologists always come out. I based my comments on statements made by various people who were there.


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

 

[Windward]

Just before the blowout, the experts on the Deepwater Horizon (DH) could not agree about how to handle the well. But this is unsubstantiated, if the standard of proof is a jury verdict. As DrillerNic says, we, including experts such as himself, could wait until we have every last detail about the blowout before assigning blame or discussing what happened. But he doesn’t and we won’t.

The immediate job is to stop the blowout and deal with the damage. There were two posts on the Oil Drum yesterday that I investigated: Operation Sombrero and a show on Discovery Channel called “Disaster in the Gulf”.

Operation Sombrero was an attempt to deal with the Ixtoc blowout in 1979. It was a gas lift pump, the subject of this thread. So far as I can tell, it worked. The best source of information on it that I can find is the book Offshore Pioneers: Brown and Root and the History of Offshore Oil and Gas. Google Books provides an excerpt, but just as it gets interesting, Google skips the important pages. If anyone can legally post the missing information, please take the time to do it:

http://books.google.com/books?id=TW...EwBjgK#v=onepage&q=operation sombrero&f=false

The Ixtoc well was in 150’ of water in the Bay of Campeche, southern GOM. Compared to the DH situation, the water pressure was low and the temperature was high. In other words, Sombrero probably didn’t have any problem with clathrate hydrates of natural gas. I hope no one will object if I continue to call them clathrates. At least it is short.

I believe it should be possible to deal with the clathrates at DH, so that a gas lift pump would work to capture all of the leaking oil and gas. I am still working on the idea, but my approach is to use the heat from the flared gas to heat the incoming seawater at the leak high enough to prevent clathrate formation. I have not yet been able to obtain a copy of the book that whammet noted above, but I have no doubt that it would provide all of the information needed to develop this idea.

Regarding the show on Discovery Channel, which I haven't seen yet, I was looking for information on it at their website and found this:

http://news.discovery.com/tech/simple-squid-solution-could-contain-oil.html

It is something like a gas lift pump, although the inventor seems to be oblivious to the high concentration of natural gas in the DH blowout. He is relying on the density difference between oil and water.

The man is trying to patent this idea. I say it won’t work because:

1. If the flow could be started, there would soon be enough pressure difference between the inside and outside of the plastic tube to collapse the tube.

2. He thinks that the oil will placidly collect on the surface for skimming. He doesn’t mention the natural gas blowing up with it. I wouldn’t want to be a skimmer on that operation.

 

[DrillerNic]

Windward- the disagreements on the rig before the suspension operation could have been about anything

1. Whether to do the inflow test as part of the suspension operation, with a cement stinger, or if to do with a dedicated work string with a check valve in it

2. the details of how to do the inflow test for example displace the riser to seawater with the drill pipe, or RIH with a mechanical packer, set just below the BOP, close the BOP displace the kill & choke lines to seawater, unset the packer.... I don't know the exact layout of the wellehad and BOP, so I don't know what methods they could have used.

3. or it could have been about something completely unrelated- a crew change flight being cancelled!

So far, we just don't know.

 

[Windward]

DrillerNic, agreed. There are many conflicting reports. Was it just bad luck after standard procedures were followed, or was it caused by a criminal corporation whose only motive is profit? Was it because those in charge of the operation had been diverted from their duties to entertain the BP executives who had arrived for a party? I don't watch the hearings, but Oil Drum reports that a BP executive has pleaded the fifth and others have refused to show. Even these facts don't prove anything.

Some knowledgeable people now fear that the casing might deteriorate to the point where the blowout becomes uncontrollable. You understand the technical reasons for this better than I do, and I hope you will comment.

If this occurs, the only recourse left is to capture the oil after it leaks, as I am proposing with the gas lift pump. The main objection to this device is that methane hydrates would plug it up, because the water is cold and the pressure is high. There is chart of the conditions for the formation of methane hydrates at

http://www.netl.doe.gov/technologie...MethaneHydrates/about-hydrates/conditions.htm

This chart indicates that these hydrates would form at the Deepwater BOP. I believe that the water is just a degree or two above freezing at the 5000' depth. It would have to be warmed to nearly 70F at that pressure to prevent clathrate formation. This might be accomplished by using the heat from the flared gas, or by injecting oxygen at the leak and causing a controlled fire in the flow.

The chart does not indicate how fast or how much clathrate would form. That is also critical information for my proposal. Maybe they wouldn't form fast enough to plug the riser, if it was big enough. One poster on the Oil Drum contributed the very interesting point that the hole in the original Top Hat, or 100 ton containment dome - which reportedly failed because of clathrate pluggage - was only 1" in diameter, even though it led to a riser that was at least 6":

http://www.theoildrum.com/node/6588#comment-647701

It certainly appears that they put a 1" orifice in this device. What do you think about this?

 

[zdas04]

The term "criminal corporation" sure is easy to throw around. If a corporation is "criminal" can you send the logo to jail? How about the documents of incorporation? This kind of talk is simply errant nonsense. A corporation cannot be happy, sad, criminal, honest, dishonest, full, hungry, or any other human condition. It is a stack of paper. Period.

Courts will decide if there was criminal activity. If there was, then that activity was performed by PEOPLE. Individuals with a physical being and free will. It is sloppy, lazy language to assign human conditions to corporations. But damn, isn't it easy. You can say "BP is a criminal organization" and in one fell swoop you can condemn 110,000 employees, a dozen board members, and many millions of stockholders. You know, those employees, board members, and stockholders are just folks trying to make a living. The vast majority of them are law abiding citizens who pay their taxes and participate in the community. Labeling us (I'm a stockholder of bp, I retired from the company, and my son currently works for them) as criminals is grossly inappropriate and I am deeply offended.

David

 

[DrillerNic]

Windward- the nightmare scenario in any blowout is that the near surface casing fractures, and then the well fluids, instead of flowing up the well, start to flow into the rock and then to surface. The well can still be killed with a relief well, but any hope of catching any oil until the relief well reaches Target Depth are lost.

I don't know if good industry practise or BP procedures or Transocean procedures were followed. What I have seen in terms of the Daily Drilling Report and the mud log released to the US Senate doesn't indicate the awful well design, poor decision making and piss poor supervision that resulted in the Montara blowout off Australia a year ago, but we havn't seen all of the details of this incident yet.

Gas hydrates form almost instantly, in the vidoes I've seen. The easiest way to stop them is to eliminate water, or to inject glycol or methanol, which is much easier than heating the well fluids up from about 4° C to 20° C or so.

I don't know the details of the original containement dome, I'm afraid. A 1" orifice would see pretty small.... I am pretty disappointed that no-one remembered about gas hydrates and thought to put a chemical injection line on it, but I guess that's what happens when you are frantically designing and fabricating the thing ASAP.

I wouldn't put the for this on BP, but on the entire oil industry that has been drilling & producing in the deep and ultra deepwater for 20 years and has developed some astounding technology to do it- DP drill rigs, riser booster pumps, Steel Catenary Risers, Free standing risers, Production Spars, Deep Draught Semi Submersibles and so on. The deepest well in the world is 10,011ft of water,and the deepest producing well is in about 8000ft of water which is awe inspiring. The industry recognised the difficulty of deep & ultra deep well control and the particular hazards of drilling in deep and ultradeep water, but focuused on preventing a blowout- no-one in the main deep water areas, in the GoM, offshore Brazil, at any stage seems to have said, "But what if it does happen, What do we do then? Do we have the gear and the techniques ready?"

Everyone's faith was put in the BOP stack- that would always work....

 

[waross]

A question aboput hydrates Nic.
Are the hydrates frozen water with gas molecules trapped in the crystal structure?
If so, does the inclusion of gas molecules change the characteristics of the ice greatly?
Are the hydrates hard ice, slushy ice or something completely different.

In a lighter vein, it seems like hydrates may be a great way to separate the gas from the oil. Now we just have to separate the hydrates from the oil.
Possibly in a future design.

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

 

[zdas04]

Hydrates are the bane of gas production. They tend to be slushy and kind of fluffy. They can block a large pipeline in a few minutes, and the blockage can take days to clear. Since they generally have considerable gas, they don't expand and break pipe like water ice can.

David

 

[Windward]

DrillerNic, suppose BP, shorthand for the BP personnel who were involved, knew about hydrates and put a 1" orifice in the cap on Top Hat. If they didn't know about hydrates, I wonder what they are doing in the deepwater oil business. If they used a 1" orifice, I can't think of any reason for it if they wanted to capture the oil and gas.

I believe they are injecting methanol into the flow on the current cap and agree that this might work in a gas lift pump. (If they knew about hydrates when designing Top Hat, why didn't they inject methanol then?) It would probably take a lot of methanol or glycol. This would not be a problem if it could be recycled, but I wonder how they would get the stuff out of the captured flow. Glycol might be easier to extract, but I don't know whether recycling of either chemical at the site is feasible. I suppose they could take the oil ashore and extract the methanol or glycol and send it back out.

It seems to me that heating might be the best method to prevent hydrate formation. There is plenty of heat available in the flared gas, but it would take some work to get it down to the location of the leak. I would try a controlled fire in the flow first. It would be easier to send oxygen down to the leak than it would be to send heated water down. We know the stoichiometry, and how much gas and oil would have to burn to raise the temperature of the flow by about 40 Fahrenheit degrees. It wouldn't be much, even if the water was half of the total flow.

Not that I am certain that a fire could be sustained in this situation. I am only suggesting that it might be worth investigating.

An expert over at the Oil Drum, handle rockman, has seen the charts of the pressures and other factors in the final stages of the DW operation. Based on those charts, he cannot believe that they did not take drastic action to prevent the blowout. Other experts are saying the same, and also that BP (shorthand) went cheap on the well, which almost guaranteed a blowout.

waross, it looks like a "clathrate hydrate of natural gas", to use the proper term, is denser than seawater, since it collects on the bottom. I know you didn't ask that question, so I am just making an observation. The website I listed in an earlier post has a lot of information on the physical form of gas hydrates, but nothing that I can find that would answer your questions. I am investigating as time allows.

 

[docellen]

Interesting thread! I wish engineers were more involved in the public discussion. There is so much misinformation in the news.

There is also an article on Wikipedia "Offshore oil spill prevention" with some interesting background on this technology. There is a link in that article to a design for a new top hat, with a seal around the BOP flange, methanol injection, and hot water flowing around the riser pipe. It may be deleted soon, however. See the discussion page.

 

[waross]

Is there water entrained in the oil/gas mix causing the formation of hydrates or it just the mixing with sea water at the leak site that is causing the problem? If they are able to exclude seawater from the collection system, will the hydrate issues mostly go away?

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

 

[BigInch]

Wonder what the EPA said about adding glycol to the mess. When only capturing some pct of the oil, glycol could escape too, wouldn't you think. lesse of 2 evils, maybe, maybe not.

"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward CEO BP
"Being GREEN isn't easy." Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.liv

 

[Windward]

waross, a few days ago someone on the Oil Drum published a spreadsheet of the production at DW. I guess they brought up some oil and gas before the blowout. Anyway, there was zero produced water for the entire time. Maybe I am confusing this with a similar field in the area, will look for this chart when I have time.

So far as I can tell, since Top Hat they have been doing everything they can to keep seawater out of the flow. I believe they are not collecting as much oil as they could with the current hat, so that the oil leaking into the sea keeps the seawater out, and they are also injecting methanol. Of course, they don't have enough capacity to lighter all of the oil they are collecting, so that probably has something to do with the amount they are allowing to leak.

An AP news article today says that they have permission to burn oil at the surface now. Therefore they can capture more of the oil than they have been, burning what they can't lighter and keeping it out of the water column, which has got to be an improvement.

docellen, thanks for the Wikipedia reference. After searching around in the references there, I found a report of research conducted by MIT on the Operation Sombrero gas lift pump, which was used on the Ixtoc blowout in 1979 (see my post above on this device):

http://www.mms.gov/tarprojects/032.htm

From the report:

"Test results indicate collection efficiencies of over 90% using the double collector positioned twenty feet above the wellhead."

The report mentions further research:

http://www.mms.gov/tarprojects/085.htm

From that link:

"As oil and gas activities move into deeper and more distant waters, the use of conventional spilled-oil recovery equipment requires further analysis. The prospects are attractive for using large, self-contained collection ships which can deploy subsea collectors over blowing wellheads while remaining on station in heavy weather, recovering oil, and separating out water. An engineering concept and cost analysis of such a system was performed."

 

[Windward]

docellen, forgot to ask in my previous post:

"There is a link in that article to a design for a new top hat, with a seal around the BOP flange, methanol injection, and hot water flowing around the riser pipe. It may be deleted soon, however. See the discussion page."

I couldn't find this information, can you provide the link? Also wonder why the article might be deleted.

 

[DrillerNic]

Windward- If you ask me to guess, the original top hat dome was designed and fabricated by a specialist well control contractor, who used a shallow water design and scaled it up. Unless you come from a deepwater background, you wouldn't even think of hydrates, and I doubt if a specialist well control guy has been involved in deepwater much. The design then got passed to a BP guy who probably concentrated on the length of time to fabricate it and could it be deployed from the boat they had on site or whould he need to find a boat with a bigger crane before saying "Yes". Having been in a similar multi disciplinary it's-all-gone-tits-up-and-we-gotta-fix-it-NOW!!! team, basic things can get missed...

There might be some water in the well fluids, if they drilled to below the oil/ water contact.... without well logs I can't say, but often the first well targets the sweet spot and the second well looks for the oil water contact.

The main issue with using heat to avoid hydrates is that 5000ft is along way down for a surface heat tracing sytem, and burning the well fluids subsea would need a lot of oxygen or air supplied down there, it would be far from controllable and heaven knows what effects it could have.... what would happen to CO2 at this depth and pressure? The lowest risk approach to stop hydrates would be to inject hydrate inhibitors, which is done in producing gas wells and pipelines already, and so is understood and controlable.

Finally, the ship on location now (the Deepwater Discovery, I think) is a drill ship, with limited tank capacity- usually when it does a well test the fluids from the well are just burnt (it's great fun, and a little scary, doing a welltest off a mobile drilling rig; the noise and the heat from the burners as you burn 8000bopd is incredible). According to the BBC BP are hoping to get an FPSO (basically an oil tanker with production facilities on the deck) on location..... isn't it lucky that the MMS has just approved the first FPSO for the GoM so it's not going to be too hard to get permission for that... with a shuttle tanker from a North Sea FPSO to ferry the oil to shore. I wonder if the Jones Act will be waived if necessary for the FPSO or the shuttle tanker, or will that cause more delays???

 

[zdas04]

Nic,
Good point about getting the heat down to where the hydrates are a risk. A long time ago, I was in a flow assurance class with a bunch of the Engineers who did the early flow assurance work on Crazy (later "Thunder") Horse in the GoM and they talked about the energy requirements that they were working under. People don't realize how big a heat sink the ocean is. One of the things they were looking at was jacketed pipe with superheated high pressure steam in the jacket. This looked promising until the simulation got near the bottom and all the steam condensed and the pipe collapsed in on itself. I never did hear what they ended up doing. Getting enough heat down that deep is a VERY difficult problem.

David

 

[Windward]

DrillerNic, that is a somewhat plausible explanation for the 1" orifice. If it is true, then it is more evidence that BP (shorthand) has been, among other things, at the very least incompetent in dealing with this disaster. If they didn't inspect the finished containment dome, or if they did and failed to notice the 1" orifice, then they ought to be removed from any control whatsoever of the DW response. It was a guy posting on the Oil Drum who saw the 1" orifice in a video. If he can see it, let’s put him in charge.

However, I am dubious that you have found the right explanation here. If there are shallow water designs for a gas lift pump collector in addition to the Sombrero, which I doubt - see my comments under handle windward at

http://www.theoildrum.com/node/6609#more

- do you suppose they would have used a riser as small as 1"? At the Ixtoc blowout, 150 foot depth, the Sombrero collector cone was almost 40 feet in diameter at the widest point. I don't know the riser diameter yet, but from pictures of the device it must be at least 1 foot.

I am also skeptical of the objections to heating the flow to prevent hydrate formation. Consider the proposal to heat the flow by injecting oxygen to maintain a controlled fire. How much oxygen would it take? For an order of magnitude calculation, suppose that the oil and gas is leaking at 100,000 bpd, to use the highest estimate I have seen yet. Suppose that an additional 100,000 barrels of seawater are entrained in the flow. Assume that the specific heat of this mixture is 1 btu/lbm/F. To raise the temperature by 40 fahrenheit degrees - as explained in the Oil Drum post noted above - we must supply heat at the rate of 117,000,000 btu/hr. This would require the combustion of about three tons per hour of the hydrocarbons. That would require about twelve tons of oxygen per hour. This seems to be lot, if the consequences of this blowout are ignored. When they are considered, twelve tons an hour is nothing.

If you have evidence that such a fire could not be lit, sustained and controlled, please provide it. As I said in my Oil Drum post, we haven’t done the research, even after the warning thirty years ago at Ixtoc that we must have some way to capture the oil and gas from a blowout

When zdas04 writes “people don’t know how big a heat sink the ocean is”, he is making the same error he accused me of making in an earlier post. How does he know I don’t realize it? While I believe that oxygen injection for a controlled fire is the best method to investigate, I don’t believe that we can rule out heating seawater at the surface and sending it down. The claim that the pipe would collapse from steam condensation is just wrong. It seems to result from an incomplete analysis of the situation.

Regarding the Jones Act, I believe that it has been overruled to allow foreign ships to operate at the blowout. There are those who would repeal the Act. They are the same people who brought on the DW disaster, global heating, the current and previous financial disasters, the criminal wars in Iraq and Afghanistan (I am a veteran of the Vietnam war. I can see these current wars for what they are. What did we learn in Vietnam? Say no to bullshit. But not enough of us have learned it.), the corruption of the US Department of Justice and many other outrages that have made the collapse of our civilization inevitable.

Also, if there had been no Jones Act, I would not have been able to get a job on the Bridgeton (ULCC) in 1989 when I sorely needed that job, although that job opened up because of the first Gulf War, which would not have happened if there had been rational and responsible people in office these past thirty years. Those who would repeal the Jones Act would only save some money for those who don’t need it. Why don’t we outsource their jobs to China? It would certainly improve matters the world over.