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Heading Out's Oil Spill Update - Including Oil Spill Discussion - May 7
Posted by Heading Out on May 7, 2010 - 10:23am
Sorry for the switch-- this is still the thread for oil spill discussion, but now includes Heading Out's update as well. It is hard to keep too many threads going at once, and we like to be able to discuss as many current issues as possible. - Gail
The last two days has seen what appears to be some progress in the capping of the Gulf oil leaks. BP is currently lowering the 100 ton dome that is intended to cap and capture oil from the middle leak of the three. The open end of the riser was also closed on May 4th by fitting a valve to the end of the pipe and closing it. There are however, two different results from the different methods of treating the problem.
Plan for sealing the second leak in the riser.
The oil is flowing out of the well, through the Blow-Out Preventer stack (BOP) which is mounted on the sea bed and into the pipe that would have initially carried the oil to the surface and the drilling rig. When the blow-out occurred, natural gas flowed up that riser, and was ignited as it left the pipe, on the platform. To help with understanding I am going to include a couple of items that I have been sent to try and give a better picture of the overall situation as well as where we are today.
Firstly, to help with some of the discussion on the structure of the rig there are a couple of pictures, first of a sister rig while aboard a ship, so that you can see the pontoons, and then with the Deepwater Horizon in the water.
When the rig is in the water the lower parts are submerged, and only the legs and platform are above the water.
When the fire began it was fueled by the initial flow of oil and gas that came up the riser from the wellhead on the sea bed, through the rig floor and engulfed the drilling mast. As I noted earlier, there is some indication that the ignition came after the power to the rig was cut, and then the emergency generators kicked in. However, initially, as can be seen from the form of the fire, the fuel was coming up the pipe from the sea bed.
Over time, the vessel began to develop a list, as the fire continued to be fought
And by this time, on the second day, the heat had burned out parts of the aluminum structure (see the helipad for example)
The rig, as you know, sank shortly thereafter.
I am going to add some illustrations to help those of us who don’t do this every day understand some of the terms and conditions that are referred to either in discussion or in the media. (Thanks to Roland V).
The first of these is the casing shoe, which is the piece of pipe that is threaded onto the bottom of the casing to help guide it into place.
Some of the components used for the casing and cementing of a well (Schlumberger)
The other area that I want to address is where the well starts on the sea bed. Remember that when we are drilling a well mud is used to cool the bit, clear the cuttings and stabilize the walls of the well. Well this normally flows up around the outside of the drill pipe, but when it gets to the sea bed it is captured between the casing that was initially set into the sea bed to stop if falling into the hole, and the high pressure drilling pipes. Thus when one looks at the area around the wellhead there are actually several pipes going into the ground.
The first of these is a relatively low pressure outer casing, that holds the surrounding ground in place as the well penetrates through it and down towards the rock with the oil in it. Within that there is a second, higher pressure tubing that will carry the fluids down to drill the well, which may be an additional 20,000 ft deeper (at 1 psi per foot rock pressure perhaps) and which must contain the oil and gas flow that will then come from that site. As an example, you can see, from this view of a Cameron assembly, through a window in the lower pressure casing to the higher pressure fittings inside.
It can also be seen in this drawing of a section of a competing design from Vetco
Vetco Subsea well assembly
Notice that there have to be seals between the high pressure drilling/production line and the lower pressure confinement casing/housing. Should high pressure fluid get into the space behind the outer casing, then it could be sufficient to crack it, and there is not always monitoring equipment in place, subsea that can check to see that this has not occurred.
There is also a passage so that the drilling fluid which flows down the central bore to the bit, can also has to come back out of the hole, and be confined as it is carried out of the well and back up to the rig where it is cleaned of cuttings and re-circulated.
It should be born in mind that the BOP sits on this assembly, and that the lowest leak is about 50 ft above the BOP, so that there are apparently no leaks in this section of the structure, as far as I can determine, at this time. The current condition of the riser above the BOP has been badly distorted by the collapse of the pipe to the sea floor. And the difficulty in fitting a cap over the assembly can be estimated from the condition of that area.
Photo of the top of the BOP (I have color corrected the image)
When the production casing is floated into the well the high-pressure drill pipe is removed, and the production casing floated into the well. It will have the assembly shown in the earlier picture, and will be sealed at the joints along its length so that the cement flows down to the shoe, and then fills the bottom of the well, and then flows back through the gap between the production casing and the rock walls, displacing the mud and filling that gap. The intent is to ensure that all the oil and gas will be forced to flow through access holes that will later be inserted through the production casing and the cement liner, using shaped charges.
There are a couple of considerations when the wells get this deep, the first being that the rock is very hot at that depth, and so the cement chemistry has to be carefully controlled to ensure that it stays liquid long enough to totally fill the gap that it is being injected into. The second area of concern lies with the pressure at which the cement is injected. Because the rock is under a lot of pressure initially, and can also be quite weak, the cement must be injected at a pressure that will be enough to drive it up along the gap, but not at too high a pressure. If the pressure is too high, then the rock around the well can be cracked. In that case some of the cement can be pumped into the crack, and the full volume fill may not be achieved, and the circulation path for the cement back to the well head may be lost.
The shape of the wiper plugs are slightly different to those that I showed in the earlier post.
The plugs are activated by first causing the plug releasing ball to be locked into the plug, sealing the flow passage, and then the pressure of the cement/driving mud will push the plug down the casing, wiping the walls as it goes. When the plug gets to the bottom of the well, the ball in the bottom plug is pushed out, and this allows the cement to flow into the gap (annulus) around the casing.
Some of this additional explanation, as I have said, is more to help fill out the background to the ongoing story.
At the present the large cap is being lowered to the second leak, and we may not know if this works until Monday. It has one advantage over the first step in the process. When the initial seal was put over the end of the riser, it closed the open end of the pipe. However the riser was split in two additional places. It is the intermediate leak that is the current target. When the pipe was capped the pressure driving the oil up out of the ground did not change. As a result, since the other two leaks are still open, all the oil that was going out of the three holes is now flowing out of two.
However when the intermediate cap is placed over the riser it will capture some of the oil, and depending on how the pressure in that cap is controlled, by drawing the oil to the surface, it might be possible not only to capture that portion of the spill, but also to reduce the pressure at that point a little, relative to the third split, so that the flow from it is also reduced a little.
It has been suggested that this idea is relatively novel, and the patent on the idea is relatively recent about 2000) though it appears to have been quite successful at shallower depths. The technique is a variation on the Riserless Mud Recovery System (RMR) that has been successful in a number of earlier wells, though at shallower depths. We will wait to see how it works this time, though I can't at the moment, see why it should not.
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Piggy Oil Companies:
I do not think oil companies clean up the oil because they care about the environment. I think they just want the oil back! If our economy gets any worse, we are just going to look at an oil spill as an opportunity for cheaper gas. We will all drive down with our tanks and clean it up ourselves. However, to add insult to injury, the oil companies only have to spend up to 75 million for the clean up. Which I am sure they will just make it back by charging us more at the pump. Leaving them with zero accountability. Let me guess, the American Tax Payer has to pay anything that goes over 75 million? THAT’S CALLED A BAIL OUT! Apparently, the oil companies are also too big to fail. I think there should be a law that says that oil companies have to give American’s free gas that is equivalent to whatever they spilt. Now that sounds more fair to me! However, they instead make a 10 BILLION DOLLAR profit. When gas went up in the 90s, President Clinton responded “It looks like someone is playing politics.” Who knows, maybe that was the day that a law being passed that stipulated they had to pay more than 75 million. Maybe they rose the gas rates to remind the President that they have the power to create and economic crisis, with one stroke of a pen. HOW DARE THESE OIL PIGGIES HOLD OUR PRESIDENTS AND THE AMERICAN ECONOMY HOSTAGE WITH THREATS OF ECONOMIC SABOTAGE!
Piggy Banks:
But there is a bigger spill on the horizon my friend. This spill is going to effect every coast line in America. It is called the GREAT FORECLOSURE SPILL! It will also keep bubbling and bubbling and bubbling foreclosures. It is still going to happen, even though the American Tax Payer funded TARP with a potential 581 BILLION DOLLARS as BAIL OUT money to the piggy banks. I mean if the government is in the lending business, why not have just loaned it to the American homeowner directly? I mean these piggy banks caused the whole mortgage crisis in the first place. TARP gave one bank $45 BILLION DOLLARS! Now that bank is potentially “playing politics” with the modification process. While dealing with the piggy banks, President Obama and Bush had the same look of fear on their face as President Clinton did with the oil companies.
HOW DARE THESE PIGGY BANKS HOLD OUR PRESIDENTS AND THE AMERICAN ECONOMY HOSTAGE WITH THREATS OF ECONOMIC SABOTAGE!
I dedicate to both the Piggy Oil Companies and Piggy Banks the following song by George Harrision and John Lennon. Appropriately titled “Piggies” I invite you to listen to it on youtube as you read the words
http://www.youtube.com/watch?v=NTmeHM-Hojg&feature=related
Have you seen the little piggies
Crawling in the dirt
And for all the little piggies
Life is getting worse
Always having dirt to play around in.
Have you seen the bigger piggies
In their starched white shirts
You will find the bigger piggies
Stirring up the dirt
Always have clean shirts to play around in.
In their ties with all their backing
They don't care what goes on around
In their eyes there's something lacking
What they need's a damn good whacking.
Everywhere there's lots of piggies
Living piggy lives
You can see them out for dinner
With their piggy wives
Clutching forks and knives to eat their bacon.
I AM FIGHTING BACK!
You can read my story or show your support in your comments at: Unitedlawgroup.com
under the John Wright vs. Bank of America Lawsuit
Please send an email to BofA CEO with “I SUPPORT JOHN WRIGHT VS. BANK OF AMERICA” : brian.t.moynihan@bankofamerica.com
Sincerely,
Johns-wright@hotmail.com
At least try to get your facts straight. It is OK to be against the oil companies, and you are certainly entitled to your own opinions, but you are not entitled to your own facts. Facts are facts.
If the oil is recovered quickly it can be cleaned and input into the refinery process but the price a refinery will pay for that oil is very low, if anything, and certainly way less than the cost of recovering it.
If the oil has weathered beyond a certain point it can not be used in a refinery and the normal process of disposal is a controlled burn at a land fill. This is an additional cost that BP will have to pay for in addition to recovering the oil. Hopefully they will locate a waste fueled power plant that can utilize the remaining oil but I'm not aware of any such power plants on the Gulf Coast.
BP is NOT limited to $75 million for the clean up and environmental damage. Their liability is unlimited - they have to pay the entire cost.
The $75 million is a limitation of economic liability - to pay fishermen, motel owners, etc who have been economically damaged by the spill. And BP has stated they will not hide behind that limit. For that we will have to wait and see.
Meanwhile a number of politicians and commentators continue to take the $75 million of out context and misrepresent what the law actually says.
It pretty much degrades to asphalt, and I'm sure it could be used for that, but fortunately there isn't a large market for refined petroleum products collected from spills. I just saw a CNN video of supposedly the first tar balls washing up on a barrier island. Looks even more like asphalt than the petroleum that regularly washes up on Southern California beaches from natural seeps. I'm used to seeing that, so that didn't look very alarming to me.
I am doubtful that BP will assume full responsibility for this event. Until they are convinced that the cannot rescue the well, yes... and so long as the economics show a profit. However, my background tells me that there is some slight of hand going on here. BP PLC is a limited liability company. It is publicly traded, and it does distribute profits to shareholders. However, there are also BP America and BP Global that I know about. Other BP's, well, I expect there are some more.
The PLC is the entity used for risky ventures. If they make a great profit, wonderful! BP Global, or whoever is major shareholder with the public, takes the lion's share, I am sure. OTOH, I work with tax laywers who specialize in asset protection every day. They create these limited liability companies for this purpose. Profits go to shareholders; if there is a major loss, bankruptcy is no big deal and they get on with life!
Believe me, if this cleanup would mean a huge loss, you will see BP PLC filing Ch-7 faster than an oil slick on the GOM!
Craig
They know they can't rescue the well - all they can do is throw money at it until they kill it.
The cleanup will mean a huge loss, already estimated into the billions of dollars.
BP is legally on the hook for the cleanup and the transferring of assets and/or bankruptcy to get out of that would probably see top executives facing jail time.
In addition it would probably put the BP group out of business. Even though they are a British company by far the largest single portion of their assets, oil fields, reserves, etc are in the US and just about all of that channels through the MMS and US government, regardless of which legal entity they are using. Default on this could get them blackballed, not only in the US but probably by other governments.
Where they have some wriggle room is in economic damage claims which are limited to $75 million. They have said they will honor legitimate claims without regard to that limitation - but time will tell.
They also have a couple partners that will probably be hurt worse than BP because they are smaller - Anadarko at 25% and another small company at 10%.
They may, or may not, have some recourse against Transocean, Halliburton and Cameron International. Other than that they are self-insured.
We can hope you are right, and they have to pay. OTOH, I am not sanguine about it. We are speaking about legalities, and courts. The Courts of the U.S. are owned by the corporatocracy - the legalities would be clear as to limited liabilty. No Court in the land would set precedent that this limitation could be broken.
Yes, BP would be blackballed. They would set up a new corporation, new name, new spin and go on with life absent the bit they pay out here and the few assets that are actually held by BP PLC. Just my opinion, but based on seeing quite a bit of this played out in courts over 25 years or so.
Or do you think that John Roberts and Clarence Thomas would rule in favor of the little guys, the fishermen say, against their buddies?
Not bloody likely!
Craig
Corp vs Corp anything can and does happen though, and a large chunk of the liability will be of that type.
Wright4ulg,
Perhaps you've noticed that oil prices have fallen by about 13% over the past week? Or that oil and gasoline prices fell by something like 70% in late 2008? From this you should be able to conclude that oil companies can't simply raise prices to cover costs.
No private business should be allowed to go above a certain level, lets say 1000 employees or $1 billion revenues. There have to be a limit. What is the maximum number of slaves owned by a non-royal-family person in rome? perhaps 500. Today's corporations' owners own a hell lot more slaves. They are slaves because they are almost fully depending on incomes from their jobs and often its very very difficult to maintain even half the living standard when you are fired. The next employer always ask what happened to your previous job.
If we have to be slaves of large corporations since large corporations are needed for progress, for example oil exploration and production company have to be big and so is the case in many other fields too, then let us be slaves of govt rather than a private business owner. A govt is obliged for many things like providing free education and medical that a private business owner is not. A govt can be brought to justice in many different ways including elections, protests, strikes and even revolutions but its very much hard to bring a private business owner to justice especially when the entire law system in modern world is controlled by money, you have very little chances to win a case in court if you can't hire an expensive lawyer, true witnesses can be silenced and fake witnesses can be introduced. On top of all that media is private corporations and in most likelihood would support a private corporation after some back-office deal and your individual voice would be unheard in the noise generated by media.
What to do? Govts should own and control all large corporations, large being a relative term should have a precise definition like the one I proposed above. Govts itself should be mostly run at local levels where people know each other and very little intervention should be made from top levels of govt. Also all govt owned corporations should have their own laws which are passed by govts and should be hard to change to enforce stability and ensurity.
When you have a large corporation, say having 200,000 employees its true can't be run at a local district level simply because of its size and also because of vast geographical area it operate in. Still a govt owned organization run even by a federal govt is much more likely to be useful to general public than a privately owned business.
Its often said that a govt run organization would be less efficient and more likely to run in losses than a privately owned business. It would not be the case if employees are given a share in profit, a significant share like 20%. Also a corporation should be given chance to run independently without political interventions from govt and only when it break a law its brought to a court by govt. A corporation should be brought to court only when it break a law, a corporate law made by govt and which is not often changed. In the routine run the corporation should run by engineers and everything need to be documented. Infact most inefficiency would be gone once the control is given to engineers from the economists. Thats counter intuitive to economists though but thats how reality works. Better still if engineers at the upper positions are bound to have an economist degree too. An economist degree in context is mostly a mba.
"...No private business should be allowed to go above a certain level, lets say ..."
thurs or fri... an amendment to the financial reform bill by sen tester (D) montana... failed... including two republicans - shelby & corker - who voted yes...
the amendment would have limited the size of financial institutions based on a formula based on their outstanding liabilities and / or a percentage of gdp...
the amendment was introduced in the senate... to limit the size of banks... and the democratic majority... aided by two republicans... could have passed it filibuster proof... but... the of the democratic majority... of 57-8-0r-9... less than 35 democrats voted for the amendment.
there you have it... "...No private business should be allowed to go above a certain level, lets say ..." NOT. the U.S. Senate - just said NO.
next idea? (sarcasm).
Rumour is, the 700 points down in 15 minutes at Dow Jones on thursday, is linked with the bill. Precisely banks and other large corporations who do almost all the trading shut down their computer which resulted in lack of buyers and prices had a free fall. More details here. We been telling since almost a century that europe and america is controlled at throat by jews, alas...nobody there listen.
On one of the posts, someone had quoted an eyewitness as saying he saw the drill floor vanish and then the generators sped up and exploded. I think that was the way it went. I’m in no tying to discredit an eyewitness’s account to this horrible event. This is just my opinion and an alternative viewpoint.
The generators were probably had a large electrical load. This may have been from the rotary table, mud pumps, or other large electrical machinery. When the explosion occurred the electrical load was suddenly dropped from the generators and consequently, the gas turbines sped up until the governors could grab it and bring the speed back to normal speed. This would take several seconds. I have been on ships where large cargo pumps or lifting of the BOP would suddenly come on line with the result the generators would bog down and the lights would dim until the governors can bring the generators back up to speed. This takes several seconds.
I don’t think the gas turbines could over speed. First, the heavy generator because of its large inertia would not allow the gas turbines to over speed. Second, the gas turbines have an over speed trip. After about 10% over speed the turbine will shut down.
Once again this is just an opinion. An eyewitness is pretty good in a court of law.
I agree. If you were ever in a hydro-electric generating station when the line breaker opened (as in an electrical storm) or a generator breaker opened you get a real speed up before the governors can slam the water doors shut. It is a real thrill if you are close to the unit.
In this case the sequence of events before and after the gas ignition will be examined very closely. If there was physical destrucxtion of any part of the electrical system that probably would be all the spark that was needed. It would be good to pinpoint the point of initial explosion but likely there was too much destruction. Not even worrying about doing forensics by ROV at 5000'.
Hopefully they will interview the eyewitnesses in a non-adversarial situation. Stress can colour the accounts even if the person is trying to be totally honest.
Thinking about the eleven families who are grieving today.
I have seen the explosion of the internal combustion engines attributed to the air intake suddenly changing from pure ocean breeze to an explosive mixture of air and natural gas. I think this process could happen faster than an engine over speeding due to loss of load. Maybe an explosion in the intake manifold could explain what observers report.
The specs for the deepwater horizon show it had 6 large wartsilla engines powering large ABB AC generators to create power for the propulsion motors and equipment on the rig.
Emergency power was handled by a much smaller 3408 Caterpillar unit.
I have to be careful what I say because I work for Caterpillar on design and engineering of these particular engines and packages. I can say this though:
The Petroleum versions of Cat engines are equipped with extensive safety features to avoid all sorts of bad things from happening. Specifically they have lots of automatic shutdown systems. With most diesel engines an off switch by itself wouldnt be enough to shut off an engine that is breathing natural gas into its intake manifold. So for this reason we also include what are know as "air shut offs" which act as simple gate valves to slam shut the supply of air into the intake manifold when engine overspeed occurs (or when anyone hits the big red button). With these in place it is in-theory impossible to overspeed and destroy the engine.
I cant tell if the witness was describing the main engines - or the much smaller single Cat engine, but I do know that the smaller Cat engine shouldnt have been able to overspeed like that if the air shut-offs actuated. Of course we also know that the cement casing shouldnt fail, Nor should the BOP. I would imagine that the Wartsilla engines are also protected by similar systems (i'm fairly sure its mandated by government regulations)
If an air shut off device failed (or was improperly installed) its easily possible that a diesel engine could overspeed not from having load removed but simply because the govenor is no longer controlling the supply of fuel. The fuel is no longer being supplied by the engines fuel system but by the enviroment the engine is in. In addition it ought to be apparent that diesel engines are not designed to run on natural gas and with high compression ratios found in diesel engines natural gas tends to be quite destructive to the engine due to detonation of the air fuel mixture in the combustion chamber. The 3408 engine would have been rated to run at 1800RPM to generate 60Hz electric power for the emergency systems (mostly lights and comm equipment). That particular engine will stay together until about 3500-4000RPM.
Phil,
Would the Cat unit be sitting cold and only set to start on auto if the main power failed? If so should I assume a delay in starting similar to a transportation unit while the glow plugs heat? It is unclear but there doesn't seem to be that kind of delay in the events as described but that could be clarified in more detailed interviews in the future.
Also, I have never seen an MG unit react to a load dump but again would not be surprised that it would be similar to having full throttle on a tractor for instance and then hitting the clutch. The ICE will definitly overspeed and activate any speed governors the same as a NG rich air intake might cause. In the end it would still activate the safety systems you describe. All of this probably is of little concern in finding out how the blow out happened but is perhaps very important in finding out why the explosion happened and how to make other rigs safer.
I also find it difficult to accept the generators went into overspeed and destructed. The T-G sets (turbine-generator, or diesel-generator) are designed to withstand overspeed for at least 30 seconds on full load rejection (loss of connected load). But the protection and control would have disconnected and started shutting down in under one second. More likely the appearance of generators destructing was they were blown off their mounts and then blew apart.
All the electrical and instrumentation devices on the rig would be explosion proof or intrinsically safe. 99% sure the circuit breakers would be vacuum bottle type, so no external spark there. However, cable(s) could have been ripped loose, or even an extension cord ripped from the explosion proof receptacle, and these could have caused the igniting spark.
But, in all my ignorance, I'll still maintain the drill string and riser had lost its grounding bond, (probably from the severe kick), either partially or completely, and the static charge caused by the high pressure water and gas rising up to the surface arced to another part of the rig. Just a WAG, but with the stated pressure the saline fluid and gas were under resulting in enormous velocity, the static charge could easily have got to 20,000-50,000 volts. Short air gaps can arc over at 2,000 volts.
"However, cable(s) could have been ripped loose, or even an extension cord ripped from the explosion proof receptacle, and these could have caused the igniting spark."
This is a very plausable cause of the ignition if the reports of massive physical damage preceeding the explosion are correct. A possible sequence could be main generators trip off line, back up tries to do its job and arcs out through damaged conductors or the arc and ignition could have happened during the event that knocked the generators off line in the first place. I hope that eventually the real causes and time line will become public knowledge.
That would make sense. In the four-stroke cycle while the piston is compressing the air-fuel mixture it would prematurely ignite, or possibly the hot cylinder walls - especially in diesel - would ignite the air-ng mixture while the piston is starting the compression part of the cycle. As each piston is in a different part of the cycle, the gross effect on the ICE would be to blow the pistons and engine apart. Essentially, igniting at least 1/2 of the cylinders at once while the piston are out of position.
Concerning the remaining leaks, there was a monitored radio transmission to the effect that...
"The box was about 4,000 feet (1,200 meters) underwater before dawn Friday, with another 1,000 feet (300 meters) to go, Coast Guard Petty Officer Shawn Eggert said."
http://www.marconews.com/news/2010/may/07/giant-box-close-being-over-oil...
Buoys are placed on the bottom to aid in placement of the box.
If the dome placement or pressure leaks around the perimeter kick up a bunch of sediment would this not put operators at full stop until they can see again?
Best hopes the results of the operation does not cloud the remote view of the scene too much.
The media says buoys but I'm sure they mean short baseline subsea acoustic transponders which can be used for extremely accurate positioning on the sea bed. They look a little like bouys when they are placed on the seabed by the ROV with the transponder floating up a foot or so above the weight holding it to the bottom.
The mud anywhere near the mouth of the Mississippi is very deep, sometime a hundred feet or more, and very soft. It will certainly kick up and I'm sure they will be all stop until it clears. The time of clearing is dependent on the current and could be from 30 seconds to 5 or 10 minutes. This will probably have a number of time during the positioning of the dome.
It is one of several reasons why it will take several hours to lower the dome the last 50 feet.
They will do everything slowly and methodically to try to avoid any mistakes and minimize the risk of damage to any of the equipment.
I'm curious if the Discoverer Enterprise is standing off and already lowering the modified drill string down to about 4,000 feet or more so they can move over the top of the dome after it is in place or if they will wait until they a stable on position before they start to lower the string.
Deep water operations are S-L-O-W. For instance if it turns out the ROV needs a special tool that was not sent down originally the time to get to the surface, install the tool and return to the bottom is a minimum of at least 2 and probably 3 hours.
shelburn, thanks for that very helpful explanation.
About Enterprise and that modified drill string, re the discussion yesterday about getting the flow established once the box is set and seems to be funneling things along, what do you think the procedure will be to establish the flow and get the seawater in the string out of the way?
It just seems that any restriction when the string is attached is going to encourage the overpressure from the well to find another way around and through the silt.
I don't know the specifics about establishing the flow but as oil enters the drill string it will displace the water in the string and establish the buoyancy necessary to start the flow. I doubt this would take more than a few minutes once the top of the dome if filled with oil.
If there is any gas entrained in the oil then that will greatly accelerate the process and controlling the pressure and flow will be required.
It is certainly possible that they have some contingency plans involving pumps or N2 injection or something similar. The one thing I'm certain of is that the starting the flow has been considered and reviewed.
Incidentally, I haven't noticed any gas in the photos/videos on the internet but then I don't think they have shown many pictures of the highest leak where the gas would go.
Thanks again.
Couple more questions if you have time.
Does the virtual representation in the bottom clip 'capturing the leaking oil' (similar to HO's diagram above) on this site match with your understanding of generally where the first dome will be applied?
http://www.examiner.com/x-48107-Gulf-Oil-Spill-Examiner~y2010m5d7-Oil-Sp...
Also just for reference. Does this video of the leak (which starts at 2:15 in this clip) probably represent only oil w/o gas entrained?
http://www.energyboom.com/policy/underwater-video-oil-pipeline-capped-gu...
Once sealed to the seabed, it will take a couple of days to get everything hooked up, Pack said. Then, it will take time to "get the balance of liquids right." That's because as the oil flows out of the ground and travels higher up the pipe, gases that are beginning to come out of solution can form hydrates. These hydrates are like ice crystals and can reduce the internal diameter of the pipe and so block it (like plaques blocking an artery). In order to prevent the formation of hydrates, warm seawater is being pumped down in the space between the drill pipe (where the oil is flowing to the ship) and the outer pipe.
from this /Live Science article.
So it appears the entrained gas coming up from that depth is a tricky entity.
I was having a bit of problem with your back of napkin calc in your post farther down. The 33 feet of freeboard you are refering to--is that how much dome must be below the leaking pipe to form the seal that will force the hydrocarbons up the riser, or the amount of pipe that must be above the sea to get flow from the pressure differential, or just the distance from the water to the works and of no real significance. I read it twice but was a little too dense to follow your path.
The 33 feet of freeboard is just my guesstimate of the distance from the ocean surface to the piping on board the drill ship. That last little bit is probably a 12 to 15 psi reduction in the pressure at the surface - assuming it is 100% oil with no gas.
thanks
best drawing I could find. I do find it all a little confusing as a BP spokesman says the tricky part is sealing the box to the bed and you and other point out there is no way it can be sealed or it will blow the box off the bed (or as I posted another day the pressure will push a hole through the mud around the box unless somehow the seawater column in the pipe can be drawn up enough to keep the pressures in check). This drawing definitely show the mud seal above the door. I'd certainly like to see a better diagram of what is really goint to happen. Those two smaller blue arrows seem important but from where do they originate or did the artist screw up and have them going the wrong direction and they were supposed to be coming from the outer riser casing as the warm mix being pumped down from the surface..but that doesn't make sense as it is supposed to be a glycol mix so I would assume it would be in a more controlled loop. Like I said I'm a bit confused.
Best, or at least the prettiest, drawing I've seen.
It is frustrating trying to get good information through the media filter.
This looks like a good drawing but it shows it installed over the end of the drill pipe which has been capped.
The area around the mouth of the Mississippi is just a huge delta of super soft, super deep mud. The flaps - properly know as mud mats - are standard for anything going into that bottom. Even offshore platform templates in that area sink about 100 feet into the mud until the mad mats at the second level hit bottom and then they are piled in.
If you look at the drawing it shows the leak in a position where it would be well below the mudline.
As I believe it is designed I give it a 50%+ chance of working, probably a higher chance of partially working.
If it is "sealed" to the leak and the bottom I would reduce that chance to less than 5%, maybe to 1%.
Stabilizing the dome is critical and the penetration into the seabed will help that. Certainly the photos I've seen of the dome do not show any attempt to make it capable of sealing to anything. But it would be easy to take the concept it has to be stable on the bottom and say "sealed to the bottom".
It is also highly probable that the BP spokespeople, including upper management, don't understand the technical details and can easily use the wrong word when under pressure from the media.
I don't think most of the media is deliberately malicious, they are usually ignorant of the technical aspects and don't properly fact check because they are trying to beat a deadline. The people who do know what is going on don't like to talk to them because what they say ends up being distorted so the reporters end up interviewing dozens of pseudo-experts and people holding dead turtles from beaches a hundred miles from the spill.
New method:
BP Lowers Dome in Effort to Catch Oil,MAY 7, 2010, 7:45 A.M. ET, WSJ
Another article on top-kill
http://www.wdsu.com/news/23469509/detail.html
Regarding the cavalcade of contingencies preceding ultimate shutdown the BP CEO seems to me to be doing his level best to manage expectations.
“This will not work perfectly at all when we first do it,” Hayward said."
Bloomberg has what seems a fairly good recent summary of the blowout, but I would appreciate what others think. It has a graphic for the relief wells to be drilled, which unfortunately I can't get to enlarge.
It puts the Macondo field in perspective, although stating Thunderhorse is producing at 300,000 bpd and is the second largest US producer...
http://preview.bloomberg.com/news/2010-05-06/bp-s-deepwater-horizon-rig-...
Never mind, the link below is better than mine
The graphic can be found on the BP site:
http://www.bp.com/gulfofmexico
Unfortunately I cannot find the path to it right now, the direct link is:
http://www.bp.com/liveassets/bp_internet/globalbp/globalbp_uk_english/in...
Was this ever posted anywhere on Oil Drum?
Whistleblower: BP Risks More Massive Catastrophes in Gulf (April 30, 2010 - Truthout)
A former contractor who worked for BP claims the oil conglomerate broke federal laws and violated its own internal procedures by failing to maintain crucial safety and engineering documents related to one of the firms other deepwater production projects in the Gulf of Mexico, according to internal emails and other documents obtained by Truthout.
The whistleblower, whose name has been withheld at the person's request because the whistleblower still works in the oil industry and fears retaliation, first raised concerns about safety issues related to BP Atlantis, the world's largest and deepest semi-submersible oil and natural gas platform, located about 200 miles south of New Orleans, in November 2008. Atlantis, which began production in October 2007, has the capacity to produce about 8.4 million gallons of oil and 180 million cubic feet of natural gas per day.
---
Last May, Mike Sawyer, a Texas-based engineer who works for Apex Safety Consultants, voluntarily agreed to evaluate BP's Atlantis subsea document database and the whistleblower's allegations regarding BP's engineering document shortfall related to Atlantis. Sawyer concluded that of the 2,108 P&IDs BP maintained that dealt specifically with the subsea components of its Atlantis production project, 85 percent did not receive engineer approval.
Even worse, 95 percent of Atlantis' subsea welding records did not receive final approval, calling into question the integrity of thousands of crucial welds on subsea components that, if they were to rupture, could result in an oil spill 30 times worse than the one that occurred after the explosion on Deepwater Horizon last week.
Full article here:
http://www.truthout.org/whistlelower-bps-other-offshore-drilling-project...
Is the lingo a little mixed up? 2,108 P&ID's?? (Process and Instrumentation Diagram) These are a master schematisc for the processes at a facility. Although I'm not an oil rig expert, given the size and systems on the rig I would expect maybe 20-30 P&ID's. Maybe a few more for the generator plant.
I think they are referring to Instrumentation loops, or loop drawings. That count sounds about right. In typical practice loop drawings are not signed off by a P.E. (P. Eng. up here in the GWN). Matter of fact, I don't think I've ever seen loop drawings signed by a P.E., but I don't work on oil rigs so take it for what its worth. Maybe I did see some for the Army Corp of Engineers signed off...
However the welds are a different story. Sounds like a contractor design-build job to me. This corner gets cut all too often and this is what happens. Not a shameless plug for professional engineers, but we are taking donations.
Start holding contractors to the same professional and public welfare accountability of P.E.'s and we'll see a whole different attitude.
This is slightly updated from yesterday’s post but I thought I would post it again for those who might have missed it.
I have been playing with some very rough calculations and trying to develop analogies that are understandable to laymen about what has happened and what is/can be done.
I’m not a downhole expert so I’ll leave that side to Rockman and others with the necessary experience.
I do have some relevant background as I retired a few years ago after almost 40 years in the offshore industry primarily in the underwater service side so I am very familiar with the ROVs, in fact some of the ROV operators currently working on the BOP used to work for me. I also was involved in building an oil capture and recovery dome (actually a pyramid) in much shallower water and was also involved in the Exxon Valdez cleanup and environmental surveys several years after that incident.
First off there is every indication that the BOP was activated and at least partially worked. It is almost a certainty that the “leak” is inside the BOP and as that oil leaks through the BOP it then finds its way through the damaged riser and drill pipe where it will exit out any open end or damaged area.
Therefore trying to repair the leaks in the riser does not decrease the flow but it can reduce the number of places where oil must be captured which is why they capped the end of the leaking drill pipe.
Every deepwater work class ROV has a sector scan sonar. Sonar can pick up oil leaks that the naked eye cannot see. The picture of oil bubbles painted on a sonar screen is like fireworks going off.
There was an ROV survey of the BOP and riser within hours after the rig sank. At that time there was no indication of any oil leakage from the BOP. And everyone breathed an extremely large, and extremely premature, sigh of relief.
Estimates made about leakage are primarily done from aerial surveys and satellite photos and are notoriously inaccurate as is clearly stated in the USCG manual on reporting oil spills. The gravity of the oil, the temperature, weather, currents, time, weathering of the oil and other factors all have a major impact on the size of a slick from a given amount of oil.
For example; if you are on a lake in very still water and pour a gallon - not a barrel, a gallon - of gasoline over the side in a matter of minutes you can have a slick covering a square mile – which will evaporate just a quickly, especially on a hot day. If you do the same with heavy crude like the Exxon Valdez spill it will probably take 500 barrels to cover that same square mile although with the fullness of time it will end up covering an area many times larger, and will take months to dissipate in the absence of heavy weather. This sweet crude is somewhere in between.
It was sometime the night after the sinking that oil leaks started appearing from buckles and holes in the riser. This was stated to be about 1,000 barrels per day. I would read that to mean the leak was between 250 and 3,000 bpd. And a 5,000 bpd leak is probably between 2,000 and 10,000 bpd. Until there is some way to measure the flow like running it through a pipeline it is impossible to have any accurate measurement of the leakage.
Factoid: If you assume that there over 5,000 psi of downhole pressure at the BOP - and everything I have heard indicates it is substantially higher than that - then a 1/4 inch hole is large enough to “leak” 5,000 barrels a day. That “leak” would probably cut off your arm if you passed it in front of it.
There is almost certainly sand in the oil and as that sand passes the leaking portion of the BOP it acts as an extremely high pressure sand blaster eroding away the area around the leak and enlarging it. So there is a perfectly rational explanation why the leak would escalate from 1,000 bpd to 5,000 bpd to ???.
Nobody was lying about the volume. The leak was, and is, getting worse.
How much is 1,000 bpd? It works out to 30 gallons per minute, about the output from 3 garden hoses running wide open, or about enough to fill a smallish backyard swimming pool in 24 hours.
Let talk about the dome a little. It would appear from the photos that the dome is designed to be large enough to encase the BOP if the broken riser were removed. It has mud mats 16 feet off the bottom so obviously the idea is to let it sink into the mud and seal the area around the leak.
It is to be connected to the drillship with a 6-7/8” drill string. I wore out a whole napkin making these calculations but if you assume the specific gravity of the oil at 0.89, the specific gravity of sea water is 1.026, the depth of 5,000 feet (actually this is of little importance in calculating the maximum flow), a freeboard of 33 feet to reach the drill ship deck piping you should be able to get about 24,000 bpd on the ship using the natural buoyancy of the oil. Most of my numbers, especially the specific gravity of the oil, are conservative so the actual output could be greater.
If there is any gas entrained in the leaking oil that will change the whole picture as the gas will expand approximately 150 times going up the drill string and act as a giant airlift so the problem won’t be getting the oil up the pipe but throttling back the flow onboard the drillship. Luckily, about the only place in the world you would expect to find the proper equipment just laying around is on a deepwater drillship.
The expanding gas also has a substantial cooling effect, enough to freeze the water entrained in the stream. So the design of the drill string has been modified t include a warm water jacket and methanol (antifreeze) injection.
They have a potentially dangerous situation separating the oil, gas and water but since the Discoverer Enterprise has processing equipment on board they should be able to handle that safely. The Enterprise also has dual draw works and drill floor so they are equipped to handle the drill string to a second dome.
This is obviously a disaster and it is quite possible that a human error or series of errors, coupled with possible equipment failure are to blame.
Does BP have culpability due to trying to move too fast? At over $500 a minute they certainly have the incentive to move fast. We don’t know - yet.
Is Transocean to blame for some sort of negligence in not properly monitoring the mud return or some other aspect of cementing process? We don’t know - yet.
Was Halliburton’s cement job faulty? We don’t know - yet.
Did Cameron International’s BOP fail due to manufacturing or design fault? We don’t know - yet.
Is a combination of one or more of the above? We don’t know - yet.
There are unsubstantiated reports that the kick registered over 30,000 psi. If the BOP stack saw that kind of pressure it could be a important factor, both in determining what happened and how to prevent it from happening again.
For those who are appalled that BP had no contingency plans in case of a spill I guess you think the skimmer vessels, the miles and miles of boom and the couple hundred trained oil spill control personnel that you see on TV just materialized out of thin air. In fact they have been on standby for a couple decades. They train, work on small spills and prepare for this type of disaster. As Rockman says; think of them as a fire department, paid for by the oil companies, under duress provided by the US government.
For those who are appalled by the lack of government response consider that the US Coast Guard was underway in minutes after the blow out and their spill response personnel as well as the teams and equipment from the oil industry were already on site standing by before the rig sank.
For a week after the initial incident, from the blowout April 20 until April 28 things weren't going well with the BOP still leaking and the weather slowing recovery operations but it is fair to say that the incident was reasonably "under control". There was no need for Obama to get directly involved, mobilize the Dept of Defense, etc.
On April 29 everything started going to hell, a true worst case scenario. That morning it was obvious the leakage from the BOP had increased dramatically. Even worse the weather changed and strong offshore winds start moving the oil directly towards some of the most sensitive barrier islands in Louisiana. Not only did the wind change direction but by evening it also increased to the point it effectively shut down all skimming and recovery operations and most boom deployments.
The media, which had only superficial coverage up to this point, got heavily involved and disseminated a great deal of information that was technically just plain incorrect.
There is a certainly an expectation that there may be someone to blame for the uncontrolled blow out with its loss of life and potential for extreme environmental and economic damage. But, it is my opinion, with some understanding of the complexities and technical and operational challenges involved, that both the oil industry and the government operational people have responded to the incident quickly and professionally. I wish I could say the same for the media, the politicians and the bloggers.
The only operation after the blow out that I might question was the decision to keep pumping water into the rig. Would it have been better to let it float and let the oil burn? But with the rigs engines and thrusters dead the only thing holding it in position was the riser so the potential of it further damaging the BOP probably played into that decision. It is always easy to Monday morning quarterback, especially if you don’t understand the technical or operational problems, but they have some of the best and most experienced people in the world working the problem.
BP has stated they will pay for the cleanup and environmental damage (as required by law) and will pay any legitimate claims for economic damage. This is a reasonable requirement. During the Exxon Valdez disaster we saw numerous outlandish claims from “fishermen” who couldn’t tell you the difference between the bow and the stern and “landowners” and “tourist industry people” who had never been to Alaska until after the spill.
There is a lot of press about a $75 million cap on BP’s liability. This has been taken out of context as it does not apply to the cleanup or environmental damage – there BP’s liability is unlimited. The $75 million is in reference to economic damage and BP has stated they will not hide behind that limit. Time will tell but at this time I take them at their word.
I’m sure this will require some effort on the part of people filing claims. For instance if you are a charter boat owner or fisherman I expect BP will require you to submit business records proving you are really in that business and substantiating the amount of business you had before and after the event. It is fair and reasonable for BP to protect themselves from scams just as it is fair that those who have been economically damaged by this event be given reasonable compensation.
I have a much greater problem understanding why the 200+ lawyers currently meeting to decide how to split up the pie should be entitled to the hundreds of millions of dollars in fees they will eventually receive.
We are lucky that this happened to one of the very few companies in the world that has the financial resources to pay the billions of dollars this will cost. This is similar to the Exxon Valdez where Exxon, despite their overwhelming arrogance, did pay all the cost of the cleanup but fought paying many of the economic damage claims I thought were valid and all of the punitive damages.
If either spill had happened to a foreign tanker firm or an independent oil company, the taxpayers would have ended up footing the cleanup bill, the people economically affect would have been out of luck and the companies would have already declared bankruptcy.
Great comments - thanks so much.
I incline strongly toward pessimism by nature, but over the past 48 hours or so I have actually found myself cultivating some serious hopes that this particular spill might very soon be under control (say within 2-3 days). How high would you rate the likelihood of such hopes?
PS: I used to post on TOD regularly, but it has been a long, long time.
Even if the coffer dam works there is still the issue of oil flowing from the drill hole, and that means any number of possible problems before they either engage the BOP, install a new BOP, or cut the flow through the two additional drill holes. That is up to three months of work, and hurricane season is coming folks.
This is a refreshing levelheaded response and I thank you for it. Let's hope that the administration and public listen to reason as well and make good dispassionate decisions and not attempt to further wreck the economy by reacting disproportionately to the disaster.
I hope that BP is as transparent as possible with what went wrong, how to prevent this in the future and how they are going to do right by all those affected and that the media doesn't get suckered in by all the ambulance chasers that just want to make a buck off of everyone's misery.
Thank you Shelburn for the best post ever written on the oil spill. It's all I need to know.
Indeed a great report Shelburne. Mucho thanks. And I can set your mind at ease over the water pumped on to the fire. The drilling rig itself has no buoyancy. In fact, it has almost no capacity to hold water. Imagine the steel frame of a building under construction and that's a fair picture. And now imagine that building sitting on two submarines. The subs would represent the two giant pontoons that actually float the rig. Can't sink a sub by spraying water on it. You may recall the statement that the rig was listing at 70 degrees. Obviously no vessel can list at that angle. What apparently happened is that the explosion ruptured one of the pontoons and it filled with sea water. The rig was actually floating on its side and not listing. Eventually the other pontoon ruptured and took on water . That was when the rig sank out of sight.
Rockman –
I have to respectfully disagree with you.
Before I do that let me say that I have followed your posts on Oil Drum for a long time although I have rarely posted myself. I find them highly informative and more than a little entertaining. Your clear and detailed explanations of what happens downhole have taught me a lot.
Although it is possible that a pontoon was ruptured during the explosions I doubt that happened. If it had I think the rig would have sunk much sooner.
The possibility of the cooling water from the work boats sinking the rig depends entirely of the condition of the water tight integrity of the rig when the crew abandoned ship. I doubt they stopped to close all the watertight doors.
I have worked on the design engineering for a couple semisubmersible MSVs and done a bunch of stability cals on them. The same characteristics that make a semi such a stable drilling or work platform in their submerged configuration also make them inherently unstable once they start to list.
A semi has a very small cut water plane when it is in the submerged condition and since the pontoons are below that water plane they do not contribute to the stability of the vessel, they only support the deck load, until the list is great enough to bring a portion of the pontoon to the surface.
On a ship shape the CG (center of gravity) is relatively close to the CB (center of buoyancy) and they have a large cut water plane so they tend to roll a great deal in comparison with a semi. Because a ships hull is wide as a ship rolls its CB shifts towards the side of the roll increasing the uprighting moment. Ship shapes can take a 45 to 60 degree or even greater roll and still want to come back upright.
On a semi the GC is very high and when they list the CB only shifts very slightly (until a pontoon breaks the surface) so it only takes a little uncontrolled flooding, especially if it concentrated in one pontoon, to impart a severe list to a semi.
Once the CG passes the CB the deed is done and the semi will capsize.
As a general rule (with lots of exceptions) ships sink from the weight of water in them and semis (in submerged configuration) capsize from instability, which requires a lot less flooding.
I guess we'll just have to agree to disagree shelburn. Though not a marine engineer I've been on many semis and I don't recall enough water tight areas that would even come close to keeping a rig floating if the potoons breached. I'll just pull a number out of the air and guess that at least 80% of the space on the rig isn't water tight. Not only not water tight but designed to drain to the sea. The mud room alone on a semi probably has more volume than all of the water tight spaces combines. But even your explanation doesn't explain how it sank if the pontoons didn't fail.
But your background in such matters should trump mine easily.
You could certainly be right. If there was not an open path of some type that allowed the water into the pontoons then you are absolutely right.
I would agree with your 80% non-water tight spaces. Normally only the pontoons and legs are considered water tight When you get water in the quarters areas it is a bit late to shut the doors and probably time to start swimming. And yes the pontoons must have flooded or the worst case she would have turned turtle and floated on her back.
But the history of capsized, or almost capsized, semis almost always goes back to a door(s) or valve left open. Thunder Horse almost became such a casualty.
shelburn -- your open door/hatch got me thinking. I know you're aware of keeping water tight while underway. I've only been on a semi when on station and everything was wide open: loading hatches, sliding bulkheads, huge vents, etc. About the only thing going for it is that the door ways always open out so water pressure would tend to push them closed. But it's not difficult to imagine that in the excitment of evac no one bothered to dog them.
Given the events leading to the blow out fit the "Perfect Storm" line I suppose the combination of water spray and lack of water tight conditions could fit too.
All pure speculation for the moment. After the well is killed and the spill cleaned we might get some answers from the rig inspection.
I understand that in the explosion on the drill deck just after the blowout, several heavy motor-generator sets 'exploded' and fell overboard. One of these could have hit a pontoon on the way down. The pontoons are outboard of the edge of the drill deck and are light aluminum structures designed to hold a few atmospheres pressure.
When BP gets arround to inspecting the wreakage on the bottom it may be obvious what caused it to sink. I wouldn't expect to see gashes in the pontoons from their settling on a soft mud bottom or from fire hoses squirting water.
Interesting question for a nautical engineer: how big a hole is needed to sink a drill rig like this in time from April 20th to 22nd?
The entire underwater structure of the Deepwater Horizon is watertight, this includes all of the space below the upper hull (deck box). There were no spaces designed to drain into the sea.
Within the pontoons were pump rooms, access spaces, and thruster spaces. Surrounding these spaces were the ballast tanks (38 in the pontoons and 4 in the horizontal braces). If you look at the floodable space in the pontoons themselves you have the empty ballast tanks and working spaces. Assuming that the watertight dampers and doors were closed (a reasonable assumption), that means that you can only flood a limited volume of the pontoon, which also assumes that the breach is not in a pressed up ballast tank.
With water being sprayed on the main deck, you would get accumulation in the spaces of the upper hull that were breached by the explosion. With free surface effect (imagine a pan filled with water) the water would collect and make a list worse. The torque from this water load would have been concentrated above the center of gravity making the effect worse.
To use numbers stated above, 3 garden hoses can add 1,000 Bbls of water per day. That is approx. 150 m³ of water, or 150 metric tonnes (I love metric conversions). The fire monitors being used to fight the fire could have placed significantly more water than this on the deck over the course of the day.
My guess is that the structure of the upper hull failed after extended exposure to high heat. The rigidity of the upper hull is necessary for the structural integrity of the rig. As the steel in the area of the moonpool is continuously heated, the steel would become weaker until it would no longer be able to supply the necessary rigidity. The stresses on the upper hull probably would have been exacerbated by the unequal loading caused by the list.
Why would a capsized rig sink, since the buoyancy is not in the superstructure? Wouldn't it simply be upside down in the water, with both pontoons at the surface then?
I'm guessing that the burning oil and gas caused the pontoons to lose their integrity and allow water into them. The other problem is that the pontoon were already submerged, so they were half way to sinking on their own regardless of any type of disaster.
There are a variety of images of the sinking here:
http://www.rigzone.com/news/incident_images.asp?inc_id=1
Since list means generally, "to tilt to one side," you're playing with semantics when you describe the drilling rig as floating on its side.
If fire boats spraying water on the drilling rig could add enough weight to sink it, then rain would do the same. It is more likely one of the pontoons was damaged.
Thanks shelburn
cf crude "500 barrels to cover that same square mile"
Any information or guestimates on the area covered by one of the leaks when it reaches the surface after rising from the ocean floor, compared to how it spreads out from there?
What are the practicalities of containing the leak at the surface?
e.g. at what point do the waves become too high or wind or currents to strong to contain an open ocean leak?
david -- the boom system they use in the GOM becomes much less effective in seas of 4' or greater. I gather that was the immediate problem after the spill started. One would think an alternative method might be considered for future problems. A 4' sea is not uncommon in the GOM especially during th winter.
BP indicates they have recovered 5,000 barrels of oil in oil/water mixture with 90% water. i.e. only 1 days worth flow.
WSJ MAY 7, 2010, 4:28 P.M. ET Dome Being Installed In Gulf; Rig Reviews Show Nothing Urgent
I can't really guess what the size of each oil leak is when it reaches the surface. I'd venture it depends greatly on how much the oil adheres to itself during the trip to the surface plus the currents it encounters on the way up amd the amount of entrained gas which will expand greatly thereby spreading the oil stream.
What I can say is that the oil can move as much as a mile away from the leak area before it reaches the surface and as currents change they could be chasing it all over. The depth of the leak certainly compounds the problem. Also where the oil surfaces is a dangerous area as the oil may be thick enough to ignite, not to mention the gas, and the fumes are dangerous to any one close by.
Weather is a major factor. It is relatively easy to recover a spill from a calm body of water.
On the other end of the spectrum a storm is Mother Natures way of cleaning up a spill. In Alaska areas that were prone to heavy storms were essentially clean after one winter while protected bays and inlets still have oil deposits more than 20 years later.
A number of years ago a tanker broke up on the Scottish coast during a North Sea winter storm. Heroic efforts by the British Coast Guard and the salvage tug crew saved most of the crew members but the tankers was completely destroyed and all the cargo spilled. There was a great fear of a massive environmental consequences. But after the storm abated there are almost no sign of the oil, the power of the storm had effectively dispersed all the oil and cleaned the rock beaches and cliffs.
Probably the worst case is what we have seen in Louisiana. 4 to 8 foot waves that push the oil past the booms (actually most of escapes UNDER the boom) but without the larger waves and white caps that will disperse the oil in such a way the environment can handle it with minimal damage.
At over $500 a minute they certainly have the incentive to move fast.
The $75 million is in reference to economic damage
Well that seventy five million dollars is over a hundred days rig time at that rate. The Gulf economy hurt by such an event could hardly equal a hundred days rig time...right. A bit of a disconnect between the value of minutes to the oil company and the value of months to the many small businesses and their employees affected don't you think.
Some people did very well cleaning up Captain Joe's spill (there is a gas station/RV park a few blocks form the Valdez waterfront unabashedly named Captain Joe's). Many Alaska fisherman who finally got a settlement twenty years later didn't come out smelling all that sweet though I'm guessing their lawyers did.
you must live in the 'burbs.
shelburn said
A may be damned if you do, fer sure damned if you don't proposition.
While people think of steel ships as fire proof, then contain all kinds of burnables. And in this case, lots of burning oil that keeps coming.
The fire can weaken the steel enough that it can then collapse or bend, possibly tearing openings, which allow fire and/or water to penetrate the vessel further.
As a fire moves around due to wind and/or fuel consumption, the steel warps, and then can tear as it cools now that it is softened.
So just letting it burn basically means it will sink sooner or later,
especially in a case where the flaming oil is at the water line.
Red hot steel at the waterline, then an odd wave (falling debris from above?), and possibly rip! - now you've got a hole - and flaming oil is now inside along with a path for water in (or air out).
Great pics of crumpled rigs after blowouts -> fires on land at:
http://www.energyindustryphotos.com/oilfield_blowout_photos_and_rig.htm
Check out the sagging drill pipe on the rack beside the remnants of the rig in the 1st picture. Burning oil isn't hot enough to melt steel, but it can soften it enough so it will sag under its own weight.
Same same with the Deepwater Horizon, except to run away you had to walk on water or jump in a lifeboat.
There were also explosions, flinging debris around, that could have punctured ballast tanks, or dented/stressing things that later broke open.
I'm not familiar with the ballast controls, but the electrical problems could have inadvertently activated valves to do the wrong thing as well, but that seems too fast for what happened.
Flooding with fire water is always a concern, but a lot of it in a fire this big is going to evaporate or run off the decks.
I think the rig was doomed without a huge amount of foam to smother the ocean surface, which was likely impossible given waves and currents.
The reason to keep spraying it down would be that if the BOP had been able to be activated and the oil cut off, the vessel might have been saved.
And something might have happened down-hole to cause the flow to decrease, and allow re-boarding, remember - they were missing 11 men, would want to recover bodies if possible.
Fire is the 2nd leading cause of ship loss after stranding.
Though it can take a couple days to sink a flaming ship - the Achille Lauro sank in 3 days from uncontrolled fire:
http://www.ssmaritime.com/achillelauro.htm
You say there is every indication that the BOP was activated. What are some of these indications? Sorry if I missed this info in an earlier discussion.
There have been quite a number of references to the fact the BOP was activated. The green lights turned red, etc.
There are numerous places on the rig where it can be activated and those controls should have all worked up until the fire burned the control system umbilical. I believe it can even be activate from the Houston office.
As the well blew for a short while before the fire, and any rig person's immediate response would have been to hit the BOP switch, it would be hard to believe that it wasn't activated.
But obviously when activated it did not work as designed.
Why? Why, why, why? In the fullness of time I'm sure we will know.
I have noticed that there seem to be many sub-specialties involved in this drilling business. I hope that nobody feels slighted or insulted, my question is could some of these accidents be occurring at the meeting places or joints from one specialist field to the next?
Sort of like at the Battle of the Bulge where the Germans hit where two army's flanks met?
A newer diagram of what is on the ocean bottom:
http://sg.wsj.net/public/resources/images/NA-BF862A_OILSP_NS_20100506192...
This diagram seems much more believable than earlier ones about which I have posted in days gone by.
Partially hidden by the sketch of the dome is a kink in the riser pipe that is not labeled and with no indication that it is leaking. Also the labeling does not indicate that the pipe in the diagram is riser as opposed to drill pipe. But it surely is riser pipe (diameter = 22 inch OD).
Labeling in an earlier diagram placed this kink at 1200 ft above the sea floor. The wreakage of Deepwater Horizon is said to be 1200 ft from the BOP in another source. The total length of riser pipe must have been 5000 ft, so there must be considerable twisting that is not shown. This is not a criticism of the artist, only a warning to someone who might want to draw conclusions from what is shown.
This diagram is sufficiently different in detail from earlier diagrams that I withdraw my earlier comments that were based of details of the seafloor situation. I think we are near enough to experiencing "ground truth" that I don't think it is useful to speculate any more.
A question: assuming this diagram is correct and the end of the riser has been capped and the cofferdam/dome is able to capture the oil from the second leak as shown won't this increase the pressure in the riser - and the flow from the leak by the BOP? Could this lead to accelerated erosion of the rupture there and thus higher flows from that point (both from the increase in pressure within the riser and the cutting action of the gritty fluid)?
I suppose there is hope that the main constriction of flow is within the BOP rather than due to the kinked riser and thus the tendency for the leak to increase would be slowed by the more massive nature of the BOP and its resistance to erosion... or is that reasoning off-base?
Has there been mention of a plan to deal with the leak at the BOP? Or is that site too dangerous to mess with?
Tis True if the cofferdam makes perfect seal then the Reservoir Inflow Performance Relationship (IPR) takes over and the journey begins to where no man has gone before. Keep the choke open and hopefully have a sleeve or some other method to let the oil out of the system prior to launch.
FF
Does anyone know the size of the roof in that thing?? Is it 20X10' feet or 200 square feet or 29,000 square inches or so??
FF
Earlier postings showed it at 14' x 24'. There are more square feet than that because it slants upwards, and that increases exposed surface.
Craig
Thank you so much. So a little over 48,000 square inches. The slant doesn't matter if I remember Archimedes correctly, as you integrate the force over the normal.... I think to get the force on submerged surface. You young guys be gentle on me though because I took fluid mechanics about 30 years ago.
So if it weighs 200,000 lbs, a 5 psi differential will lift its weight, not including the drag to push it up out of the muck.
Interesting.
FF
I agree! It would seem that the thing should get sent right back to the surface!
OTOH, even a small difference might tip it over if it is not precisely lowered.
There are many problems with this device.
Craig
Anything over 2 psi will vent oil out the slots, IMHO. It might tip, but the flaps will help. Who knows, maybe they'll sandbag it?
The engineers have really nice toys for doing a model, I'm sure. We may not be quite sure of the forces with rough estimates, but they are getting that way by now.
I'm more worried about second-order issues -- icing, mud clogs, mechanical issues on planting it, ship-based controls, mud depth, and so forth.
Engineers are smart, and they've had days. If we can rough it out in 10 minutes of on-line breaks, they can do wonders with 24-hour focus.
Is the dome being lowered 'hot', with the plumbing attached? Or will that be connected after the dome is set? Playing in the deep is surely quite an operation - hopefully planning (and a good helping of luck) will put the odds in their favor.
No - one DP vessel is lowering the containment vessel. When it is in place the the Discoverer Enterprise will move over the top and make the connection. Pretty standard procedure for a drill ship.
If you want to play some more with this don't forget to include the buoyancy of the steel, wood and concrete in water. Seawater is 64 lb/cubic foot.
You may well have hit on why the weight of the dome increased from initial reports of about 60 tons to over 100 tons but the size of the dome did not increase.
I took fluid mechanics about 40 years ago but I have always enjoyed helping young people.
If the 40' dome is half-planted in mud, then the 20' remaining, if filled with oil, would exert about 2 psi of lift. The column, if filled with oil and capped at the top, would add 500 psi for the pipe diameter. It would be worse if the pipe partially filled with gas.
But then there is a bunch of pipe holding it down as well.
100,000lbs seems like its in the ballpark of max lift, but I'm pretty sure their engineers can do the math precisely, and if needed they could weight the dome further. Plus, the mix should be heavily water, so the worst case is very conservative.
The problem I see is that this is great, if you are just talking about filling it and letting it run up the pipe. OTOH, it is coming into the bell at pressure. Once the bell fills up, the rest backs up less whatever goes up the stack. Or it leaks out, which is the same thing. If oil is coming in at 550psi, it has to go out with sufficient volume to empty the vessel. How is that being done?
Craig
If the oil is mixed with gas, when the top is closed the gas should collect at the top and force the oil out the windows until the bottom of the gas reaches the top of the windows. At that point you have a lot (almost 300,000 lbs??) of flotation force, which would float the dome. Sure hope I am wrong.
I wonder if that places a limit on how much backpressure will build and then how much additional flow will come out the BOP leak??
FF
Unless there is a strong pump forcing the oil out of the containment vessel, it will indeed increase pressure backwards on the line. At least that would be my take on it. Physics demands it, in fact.
Craig
Are you figuring that by starting from that end they may get a chimney effect going so as to draw from the BOP leak and slow it down? (or rather divert it into the new riser)
According to a couple of articles the idea of a top-kill to the BOP has gained popularity at BP in the last 48 hrs. If the above idea has merit perhaps it could be part of the new strategy.
I'd say the leaks are independent, and hopefully they're doing the bigger one first?
I just hope the leak rate is determined by the BOP and not the crimped pipe.
Yeah for sure. Hearing all this talk about the dome rising from the mud I think I just figured out what those little capture gate bars at the bottom of the slots are for. But like you say if it exerts any pressure at all it'll probably just leak.
Edit:
To me the one of the best unanswered questions (from Paleocon and FF) is what are the pressure drops across the two remaining leaks. Is the BOP holding back the volume or is the kink in the pipe. I have no idea if engineers know this info for sure or not. If the kink was actually the restriction and the BOP hasn't collapsed the string much at all maybe there is an added problem with disturbing the riser.
Best hopes for good gentle capture and placement expertise.
There is really no chance of back pressure of more than a couple psi (distance from the leak to the seabed times the delta of specific gravity of the oil vs seawater) because any additional pressure will just force the oil out of the dome.
The same holds true for a pressure reduction (suction) as seawater will enter the dome and reduce the pressure. They certainly don't want suction as it will probably stir up the mud and they have will have enough to contend with separating the oil, gas and water.
I'm not sure what mechanism has been included to measure the oil level in the dome but I'm sure they have figured exactly where they want the oil/water interface and will control that level from the surface by adjusting valves.
If there are two paths for the leaking oil - the leak near the BOP and through the dome/recovery system - which one will physics prefer? How much differential will there be between oil flowing directly from the leaking riser and oil reaching the surface ship through the plumbing system? About equal? Small difference? I am assuming the leaking riser will be favored, but perhaps I am missing something.
That was FF's original point. If the pressure is not relieved, physics pushes the oil out the path of least resistance. A slight reduction would be likely, but just equal to the amount that is pumped out of the dome or rises 'naturally.' IMO that would be not much.
Craig
If oil is coming in at 700 psi (I have heard that as a low, 5,000psi as a high, but take the low), and there is no suction, it is going to exert one heck of lot of pressure on the top of the dome. Unless the bottom is sealed to the seabed, the pressure will pop that puppy up like a cork. Hence, you need a pump. Cannot suck it out, though. You have to use a centrifugal pump and force it up. The pressure of the CP has to match the incoming pressure pretty much exactly. Too much, and you suck up the seabed. Too little, and you float the dome.
Craig
I posted a version yesterday.
What everyone seems to be missing is that the reservoir has an Inflow Performance Relationship (IPR curve). That is rate versus pressure. Let's say one point is 40,000 BOPD versus 2,300 psi. This is what BP told Nancy P about unrestricted flow. Let's say another point is 0 rate and 6,000 psi. This is the x intercept. Draw a straight line between those points. This is what the reservoir can deliver against what it sees, backpressure. It doesn't have to be straight but this problem will get complex enough soon enough.
Now we have a downhole choke on that--which is the kink. So there is a pressure drop across the kink which inhibits the IPR curve. Instead of 40,000 BOPD against 2,300 psi we have 5,000 BOPD--- let's say(I'm not here to argue that). So we need to shift our reservoir IPR curve down for that choke. Still, we get 6,000 psi eventually at 0 rate.
The other curve is the tubing curve. This is the 5,000' of 6" ID pipe to surface. We need to build a rate versus pressure curve for that, which many of you have done. It depends of course on the surface pressure, the gravity of fluid in the tubing, and the frictional loss.
I would suggest that you need a family of tubing curves for varying water cut's. We definitely have an extraneous source of water in the methanol line, but also we cannot assume a perfect seal around the box. Also, we do not know that the well is not making saltwater.
Nodal Analysis implies the entry point in the top of that cofferdam is a node---where the 2 system curves intersect... the reservoir curve and the tubing curve-- that is a stable operating point.
Now let's say that the box leaks like a sieve. The seawater invades and the fluid in the the tubing is 99% water. What happens??. Then assume the box is tight and dry oil is coming to see you. You have to shut in for a problem on the surface (this is going to happen). What happens??
For an engineer or physicist, these thoughts and other time dependent possibilities should cause a nice seratonin (sp?) release. Enjoy.
FF
Let’s say that sucker delivers 40,000 BPD at 2300 psi, and if capped of entirely the pressure is 6,000 psi. Is your pressure to deliver rate a straight line curve, that is, does pressure automatically go up as flow is restricted? I thought the pressure was more or less uniform per sq. inch, and if you have a flow restricted to 0.75” from 6’, it should cut down on delivery but not pressure psi. Then, thinking this through, if you have 5,000 bpd (the figure presently in use), that is 1/8 the flow, so from that you could compute the degree of restriction from the kink.
One problem I have heard cited is that sand and oil and gas is going through that kink at a fairly high rate of speed, at a pressure of – what, 550 psi? The mixture is grinding away at the pipe, and may well eat up the kink. At which point, you are at your full pressure, 2,300 psi, and flow, 40,000 bpd.
Also, my recollection of fluid dynamics is that the pressure is the same throughout. This is the theory behind Westinghouse’s air brakes. The pressure declines only when the restrictions are relieved. Translated, that means that if you have 2300 psi coming up 6”, and neck it down to 0.75”, you still have 2300 psi. However, once the oil comes out, it expands and the pressure goes way down. If you cap it, you get the 5,000 bpd flow coming in to the bell, and if you have a 6” pipe restricting it, the reduced pressure is about 550 or so psi. That is still a good bit of pressure to deal with.
Back to the original question… the flow is coming in to the bell at an effective 550 psi through an effective opening of 1/8 of 6” or 0.75”. It is going towards a 6” pipe that must remove it at sufficient flow rate to match the incoming, under pressure. It would go right up the pipe, if only the bell were nailed down. Instead we are using weight (40t is the figure I heard), and perhaps a bit of surface tension to hold down the bell. Two problems that high pressure input might cause, IMO, are: if the bell is not level, it pushes on one side more than the other and tips it over. Yeah, I know, there are tabs on the sides; not very big, though. But, let’s say they are sufficient. You still have to equal the upwards pressure to keep the bell on the ocean floor (or to keep the oil from squirting out the slot on the side).
Now, if the bell is actually sealed down to the bottom sufficiently well to hold all that pressure, and there is a 6” hole to accommodate the flow, the oil will go up the 6” hole if that is the easiest way to get out. Meanwhile, back at the BOP, you have another leak that is going up into no restriction at all… the oil goes there because it is much easier. You would have to cap the third leak in order to get the oil to go up the pipe, without a pump. Also, the third leak, which would then have more of the flow, would erode the pipe much faster… the fear of the PTB.
Another problem I have not seen addressed: Looking at the bell, it has a slot and those tabs; it is going to be lowered over the riser, we presume toward the BOP and away from the valve placed at the end, at what is designated as leak #2. Leak#3 is at the wellhead/BOP. There will be riser between the slot and the BOP, and the bell will cut into the seabed up to the tabs. Otherwise, the oil would be going out the slot almost immediately. So, it drops into the seabed (assume there is no pressure keeping this from happening, which I doubt) until the tabs hold it up. The bell is now resting on the seabed, and on the riser coming from the BOP, and if the earlier valve is not inside the bell, it is also cutting into the upper portion of the riser. What impact does this have on these portions of the riser? Are the crimped off? Or cut off? Bent, and deformed? I see the best case as crimped off. Or, the upper portion, towards the new valve in place, is cut off and the lower part, toward the BOP is crimped. Crimping would impede the flow of material, and increase the leak at the BOP.
In any case, these people have a boatload of problems and less than a canoe worth of solutions, IMHO.
Craig
Zap IMVHO;
If the sediment is soft enough for the bell to sink into the seabed the bet is it will be soft enough to allow the pipe to sink in too and not deform.
Looks like the dome is not designed to seal against the seabed at all but to provide a sufficient collection for an oil/seawater level to be maintained. If the sweep is insufficient then the dome will allow the overpressure out through the slots or exit back at the BOP. Then a gas kick ??
The specific gravity of the oil/water/gas appears to be enough less than seawater to provide sufficient buoyancy drive to overcome frictional loss and then some to deliver the mixture to the surface with pressure to spare. This balancing act to most everyone's expectation will not go flawlessly.
Just picking up what's been laying around TOD today.
AP is reporting that the dome is now on the seabed and needs ~12 hrs to settle before they start connecting the plumbing. Looks like step 1 is complete. I also read that they will try the same procedure with the remaining leak if this approach proves successful.
I just caught that too. As you just said.
http://www.wwltv.com/news/Containment-dome--93155554.html
5 percent doesn't sound good. Why so little? Is it because as it contains the leak, it forces oil to go out the other leak? Would capping the other leak the same way only realize 5% capture? I guess its better than nothing. These figures are confusing.
Craig
Best hopes for a missing 0. ;-) Gogglin'
This one says 85%
http://www.marcoislandflorida.com/apps/pbcs.dll/article?AID=/20100507/GR...
We like gumbo, too.
They mean 85%, but that's just an earlier estimate repeated.
"By Sunday, the box the size of a house could be capturing up to 85 percent of the oil. "
http://www.google.com/hostednews/ap/article/ALeqM5gIXWYBTpLtSayJtg41LKXp...
I think you are trying to over engineer the problem and confusing boundary conditions.
First and foremost - the dome (containment vessel) CAN NOT sealed - at all, it must be open to the surrounding water pressure. If it was sealed it would either immediately be blown off if there was a pressure build up (as you pointed out 5 psi pressure build up would be more than enough) or any negative pressure would suck the surrounding mud sea bed right up into the drill string (the principal behind suction anchors for drill rigs) and possibly collapse the containment vessel.
Therefore it has no effect (other than possibly a psi or so) on the well, riser, leaks etc. so it won't have any effect on the leak rate, etc.
The recovery calculations start with the leak at ambient pressure and then you can calculate theoretical static pressure and flow conditions.
The following theoretically assumes there is no gas in the oil - this is a bad assumption but you have to start somewhere.
Static pressure if the drill string is filled with oil is entirely dependent on the specific gravity of the oil and the actual water depth. Roughly if the specific gravity is 0.80 then the pressure at the water surface would be about 500 psi, if the specific gravity is 0.90 the pressure would be just under 300 psi.
A rough calculation of the maximum flow rate is probably in the order of 20,000 to 30,000 bpd, it could be considerably more if the oil is really light. The major component is the specific gravity of the oil and then the friction loss in the drill string. When the friction loss balances the pressure differential of the oil vs sea water you have reached maximum flow. Minor factors like the viscosity, number and design of joints, etc will have also have an effect. I assumed a freeboard of 30 feet at the vessel.
In real life the gas entrained will make a major difference. If the drill string was filled with gas the static pressure at the surface would be over 2,200 psi. As soon as you start mixed flow you get into undefined territory.
The control system will to be to monitor the level of the oil/water interface inside the dome and throttle the flow at top of the drill string to keep the oil/water interface at a set level.
The rig can easily handle the maximum static pressure of about 2,200 psi but having gas in the system will make it have some "kicks" similar to a water hammer in your home plumbing but much higher pressure. They may have a system to handle that or may calculate the on board system is strong enough to withstand any kicks.
First and foremost - the dome (containment vessel) CAN NOT sealed - "
Nor would that be desirable in any event from my perspective as a non engineer.
First off, thanks. I read the thread above and was about ready attempt to make many of the same points you made [although you did a much better job than I could.]
I am a little surprised that no one has drawn the analogy to an oil water separator. If the bell is of sufficient volume to allow the highly energetic oil to separate and rise to the top of the bell the lower specific gravity the oil and the resulting lower total weight of the oil column [versus the normal pressure of a salt walter column] should cause the oil to flow to the surface.
Even if the separation of oil and water is far less than complete the emulsion would still be lighter than pure seawater and if needed for sufficient flow a properly sized REDA could do the trick by reducing the static pressure at the intake to the REDA to aid increasing the flow of the emulsion to the surface.
Hope I got it right as I am not an engineer or an offshore oilman since this can be a tough crowd.
Sorry, it is so easy to just assume people understand the dynamics. I started writing this series of posts just to try to explain to people not involved in our industry what is happening and find I am doing a poor job and leaving gaping holes in my explanations.
First - The dome should definitely act as a separator and minimize the amount of water going up the drill string, but even better -
Second - If I understand the plan correctly the leak will probably be above the oil/water interface which means if the containment vessel is working smoothly the oil leaking from the riser will never come in contact with the water before it heads up the drill string.
This is the part I have difficulty understanding (or envisaging). What will make the oil-seawater interface stable - sitting somewhere between the top of the dome and the seabed, and presumably higher than the door? How can they match the leak rate with the extraction rate at the surface?
And secondly, how will they position the end of the leaking pipe so that it is discharging directly into the trapped oil and therefore not into the seawater or sediment? And if they did do that successfully, wouldn't the pressure of the discharge make things very turbulent inside the dome?
(1) They will have an oil-water separator on the ship above, so it doesn't matter if they suck in some water. An ROV at the door will tell them they need to step up the pumping (if indeed they need to pump at all per discussion above re the oil with gas bubbles' buoyancy).
The leak is (from the drawing) below the sea floor, the mudflaps on the dome are to keep it from sinking totally into the mud. So the leak is below the oil/water interface in the dome.
(2) The oil is apparently not spurting out that fast, remember the sea is providing about 2000 psi backpressure. Did you see the video of capping the drill stem?
The end of the leaking riser is where it is. The 21" riser pipe is probably not moving.
Did you see this drawing:?
http://www.bp.com/liveassets/bp_internet/globalbp/globalbp_uk_english/in...
The riser has a big piece of drill pipe sticking out, anchoring it in place.
Here's a picture of a piece of riser pipe:
http://www.oceanleadership.org/wp-content/uploads/2009/08/riser-pipe.jpg
Note the man for scale. While some of the pipe is made almost buoyant by the foam jacket, it is still a 21" diameter heavy wall steel pipe bolted together with bolts the size of a man's arm:
http://www.drillingahead.com/forum/topics/transocean-deepwater-horizon-1
The only thing that would move it much is a sinking drilling rig.
Thinking about it, the near 90 degree bend in the drill pipe as it exits the riser makes sense now, as does the rectangular plan of the dome and the placement of the dome doors: http://www.theoildrum.com/node/6437#comment-619623
The top of the riser broke off the rig, the drill stem was blown out or yanked out a ways if it broke loose from the rig after the riser, so the drill pipe was sticking out and hit the bottom first, the riser end comes down after, bending the drill pipe and burying the spot where the riser ends.
Also explains some of their caution is setting the dome down - that small spot on the seafloor is fluidized by bubbling crude. I wanna see pictures!
just think, you have a mile of pipe hooked to a little concrete, steel and interior timber supported box, that is only sunk fifteen feet into very soft, high water content mud. Not the most stable base to be contending with. The drawing I posted shows the leak below the external mudline because the top of the door which is located below the flaps has pushed the pipe down. Mud will not remain above the pipe end.
The sea is providing that same down pressure in the pipe which is to be attached to the now placed box as it is to everything else at that depth. Is the seafloor enclosed in the box going to act as a single solid large piston surface and push the fluid proportionally higher in the small pipe on top until the downward water pressure in the pipe is so reduced as to make the top the much easier escape or will the mud going to get real active and open a path under the box walls?
Of course if the pipe cross section quickly gets reduced by hydrates and mud freezing to the side all calculations are off. I'm betting they have a bunch of possible contingency plans about how to deal with that hookup which means they are more or less shooting from the hip. The only statement I've read so far said balancing the pressures would be tricky--which I believe is exactly what I wrote the other day--I'd like to get a little more detailed info from the boys planning the work than that. Well if and when they get it to work (I'm thinking they just might) they will tell us all about how it went.
"I'd like to get a little more detailed info from the boys planning the work than that. Well if and when they get it to work (I'm thi"king they just might)"
I'm thinking they just might too.
Been looking at the pictures of the outside and the inside of the dome some. Given all the above discussion, even though a good stable 'seal' around the seabed is probably good for not stirring up sediment flows in that area, I doubt seriously the chamber to be be isolated from seawater pressure at all.
The numerous pipes ,two straight and several angled, sticking out of the top sides of the dome would be enough to spill an overpressure in the dome and insure the oil/water(gas) interface does not procede below a certain very high level. Bouyancy drive is most likely being counted on as sufficient to carry the oil column to the surface and beyond. Gas entrained in the oil would accellerate the process and sweep the dome faster.
But then their is the hydrate freezing problem. I can't tell how the warm water-glycol mix is going to spill or return in the piping scheme. Some of the oil folks here think is may not be too bad a problem once the flow is up and running. It seems a gas bubble will form in the top of the dome if the delivery clogs and then we hope they have the lifting capability of that difference well calculated.
After all I learned on TOD in this thread, a pretty darn good scheme. IMVHO
Officials discovered that gas hydrates, ice-like crystals lighter than water, had built up inside the 100-ton metal container. The hydrates were beginning to make the dome buoyant, and they also plugged up the top of the dome, preventing it from being effective.
“I wouldn’t say it has failed yet,” Doug Suttles, BP’s chief operating officer, said at a news conference in Robert, La. “What we attempted to do last night hasn’t worked.”
As a consequence, crews had to lift the dome off the well and place it on the seabed.
From the NY Times
Like I said they are pretty much shooting from the hip. I didn't pick up on all those exit pipes up top, probably because they are relatively small diameter which appears to be a bit of a problem now. What fun they are not having!! Where did you find pictures of the inside of the dome?
If the oil is mixed with gas, when the top is closed the gas should collect at the top and force the oil out the windows until the bottom of the gas reaches the top of the windows. At that point you have a lot (almost 300,000 lbs??) of flotation force, which would float the dome. Sure hope I am wrong.
Although I didn't anticipate the formation of hydrates to be the cause of closing the dome top, bouyancy certainly looked like a problem to me. This was one of those times when I really didn't want to be right. At least now they know bouyancy is a problem without having damaged anything, so maybe they can account for it when they plan their next move.
Thanks for that ... and yes, I have checked all the relevant links you have re-linked. The sheer scale of all this undersea pipery is quite sobering ... and I will be amazed if the dome capture system works even half-well.
At the time I wrote that the wrote the leak would be above the oil/water interface I had just seen a media depiction showing the dome going over the BOP and the leak coming from the riser crimp.
I thought they might be correct - silly me - and from that concluded the leak would be above the oil/water interface.
Shelburn-
You obviously are a better facilities designer than I could ever hope to be. I should stick to my reservoir engineering ---and find trouble often there.
What your talking about is a gunbarrel- I have 50 of em. To be honest, I never really thought about it-- I thought about the white box as an enlarged section of pipe.
But if you think about that Node which is the inlet to the 6" headed North, it seems to hope for a stable pressure there in a steady state condition.... I've bucket tested wells with dissolved gas and that node pressure when trying to control it from 5000' above is going to be swinging wildly. Now all the permutations that causes may "even out"- I don't know.
I post my thoughts here so I don't drive the wife crazy and still enjoying learning. Thanks for your contributions.
I hope it all works fantastic.
PS- Paleocon as well
FF
Thanks, but I can take no credit, other than for checking math and doing a couple free-body diagrams to re-calibrate my own intuition. Like I said, I've gone from skeptical to reasonably confident the physics will work just fine, but like you and others point out, it's a difficult environment. No way this contraption is going to be a sturdy anchor like a well-head and BOP, and a big gas kick could maybe pop the thing out of the mud. Or maybe gas will just blow out the doors if kicks come, and with a little throttling at the surface the transport will be self-optimizing.
Note that BP said they were shooting for 85% capture, and that gives them some wiggle-room to tune the system and deal with surprises.
Sometimes you get lucky. I hope this one is such a case.
Edit: The 85% number is, from what I've seen elsewhere, a repeat of an old number that 85% of the oil is coming from this leak. It is otherwise a meaningless number, and I have seen nothing about capture expectations and probabilities by engineers.
I spent 30 minutes googling for a good description of the physics behind the dome, and found zilch. Nada. Out of the entire press world it seems that nobody has actually provided a technical discussion of how it is supposed to work. I think the analysis in the comments here at TOD are actually the most thorough treatment so far.
Any high-school physics class should be able to do the same analysis.
So, the oil would go up at the speed determined by the specific gravity, as compared with the sea water. Being lighter, it wants to go up. That I understand. I will wait and see the effect when everything is hooked up. If the vessel is on the bottom, and over the leak, but no pipes are connected, the oil should be spilling out the sides/slots. Hook up the pipes and it wants to go up, sort of like antigravity. That I understand as well. And, if you say that will result in pressure sufficient to bring the oil up, I will have to take your word for it.
Sure hope this works! I really like gumbo!
Craig
shelburn,
If I understand you correctly, you are saying that the difference in density bewteen the oil/ gas mixture and water is sufficient to drive up to thirty thousand barrelsa day thru the riser.This is a lot more than I would have guessed;earlier I posted a speculation that maybe a pump would be needed.
There still seems to be a distinct possibility the flow could increase to well over thirty thousand barrels a day due to sand in the oil abrading the pipe and existing plumbing and enlarging the hole or holes thru which it is escaping.
Will it be possible to fit a pump into this jury rigged repair if one is needed later?If so, how long might this take?
If there is any gas in with the oil it will act as airlift - almost a controlled blowout - as the gas rising in the pipe expands. They will have to control that by keeping pressure on the the system at the top until they have an equilibrium that works.
I wouldn't even speculate how much volume you could get through the drill string with expanding gas bubbles - how much oil can get through through a 6-7/8 inch drill string during a blow out?
In the very unlikely case that there is no gas in the leak AND the leakage is in excess of 20,000 plus bpd then additional help will be required. The easiest way is to inject some air into the drill string about 100 to 200 feet below the ocean surface.
Us old dumb divers are lazy and we like to let the ocean do our work for us.
Three phase upflow. Not exactly something that there's a lot of good correlations for.
The pump is gravity driven, by the density gradient between oil and water.
If the dome is filled with oil, it will exert 2 psi or so at most, and any additional oil will spill out the doors. The dome is not a pressure vessel, just an inverted funnel, so it'll never hold in any oil under pressure at all.
But really, as the gravity pump works, it'll suck in water instead of blowing out oil.........if it all works as planne.
Additional twisting is not necessary. The diagram shows the elevated kink to be the apex of a triangle. If the height of the triangle is 1,200 feet, then the lengths of the sides are greater. If the angles at the base of the triangle are 65 degrees, the rising sides are 1,324 feet each and the base is 1,120 feet. With the distance to the drilling rig at 1,200 feet and the pipe end folded back on the sea floor a few hundred feet, adding it up to 5,000 feet is easy.
BP's letter to drillers warns of equipment changes
More from BP COO on efforts to stop Gulf spill
Oil riggers recount fateful night
U.S. Homeland Security Monitoring Blogs, Websites Reporting On Gulf Oil Spill.
http://www.eurasiareview.com/2010/05/us-homeland-monitoring-blogs-websites.html
hmmm... I wonder if westtexas or alan has any unmarked black trucks parked outside his house...
Sometimes paranoids are just better informed.
I am reminded of an incident a few years ago. Alan Drake and I collaborated on a column for the Dallas Morning News, taking the "Yes we have peaked" side of a Peak Oil debate. I think that I mentioned that Saudi Arabia had probably peaked. In any case, shortly after the piece was published, the head of the Dallas Morning New editorial department was visited by the Saudi Consul, from their Houston Consulate Office. The head of the editorial department was noncommittal when I asked her what they talked about, but I noticed that I was not invited to do any more Peak Oil columns.
Interestingly, TOD does not appear on the list the published. Admittedly, it was not a full list, but still... I am insulted!
Craig
It OK zap. Just got the memo from my controller at Exxon and you're #5 on the list. But hang in there...I'm sure if you post enough you'll get bumped up.
We're on the other (blind squirrel, just keep 'em hunting) list!
Surely Bumped Off? :-)
Ouch! I represent that remark!
;>)
Craig
Here's an alternate take from Altenet at http://www.alternet.org/world/146771/the_gross_negligence_of_bp_--_oil_g...
The article spends most of its length railing at BP for not having enough boom and crews on hand to deal with a spill, then near the end launches this:
"This just in: Becnel tells me that one of the platform workers has informed him that the BP well was apparently deeper than the 18,000 feet depth reported. BP failed to communicate that additional depth to Halliburton crews who therefore poured in too small a cement cap for the additional pressure caused by the extra depth. So it blew."
Again I'm in the uncomfortable position of sounding like a BP defender but there are hands working for at least 4 or 5 different subcontractors that independently know how deep the hole is, how deep the casing was run, how much annular volume there was to fill with cement and most of the other details. In fact, much of this communication goes on directly between the subcontractors doing the actual work and often doesn't pass through the BP company man.
But I can understand how such confusion happens. There isn't just one number for how deep a well is drilled. There the depth that the hole reached which could be in "measured depth" feet or "true vertical" feet if it was drilled at an angle. Then there's the plug back depth when you pull back from the TD (total depth). TD can even vary. The driller reaches X' (DTD) but the logging company might only reach X' - 100' (LTD). Then there's the depth that the casing is run into the hole which is often not all the way to the TD. So when someone says a well was down at 18,000' it doesn't really tell what you might think: was it drilled to 18,800' but csg run to only 18,000'? It's easy to miscommunication.
But again, there are multiple independent eyes looking at the same numbers. BP might have given the Halliburton hand a number but that hand used data from another contractor to do his calculations and then the driller had to go into the hole based upon his own numbers. But that doesn't mean mistakes aren't made. That human element again.
Rockman:
You describe a lot of different places near the bottom of the well that might be the bottom end of the length measurement. For me, there is a question about where the top of the well is what might explain the a differnce.
I know from talking to people putting new casing in local gas wells here in Colorado that they count the depth of a well starting at ground level where they are which is 5000 ft above sealevel. This is very reasonable because it is what counts in figuring how much new casing you have on hand to do the job. Would not the same convention apply to off shore wells? You measure down from the well head which is not where the drilling rig is, but 5000 ft less.
But if you are talking to a visiting rube or a respected government dignitary standing on the drill deck. What is the correct answer to "How far down is the bottom of the well?"? Could this be the source of misunderstanding?
Always possible geek. If you ask me how deep is the well I might say: 5,000' which is the water depth; 23,000' which is how deep it was drilld; 18,000' which is how deep the casing was set. It could also be 17,400 if it's a completed well and that's the depth it was perforated.
But back to the point: there are so many different hands involved in complex computations it's difficult to believe that was this was source of the incident. But who knows, it could have been the "Perfet Storm" of miscommunication.
But for the third time I've seen it reported that the company man on the rig didn't want to displace the riser before setting the top safety plug. But some BP engineer ordered him to proceed. The truth will eventually come out in the hearing.
See, if they used metric there wouldn't be this confusion ;-)
"Government Exempted BP from Environmental Review
Salazar-ken
Newly-released documents show government regulators exempted BP from a comprehensive environmental review of the project that resulted in the spill. The Minerals Management Service granted BP a “categorical exclusion” from a full review before approving the project just over a year ago. We speak with Kieran Suckling, executive director of the Center for Biological Diversity. [Includes rush transcript]"
http://www.democracynow.org/2010/5/7/government_exempted_bp_from_environ...
The above interview is just one of recent revelation of how MMS and BP worked together to skirt regulations. Ken Salazar should step down - all we need now is for Pres. Obama to say "Heck of a job Ken"
Recommended reading
"An American Chernobyl
by Dmitry Orlov "
http://www.energybulletin.net/node/52716
If Chernobyl was the sign that the Soviet Union was about to add Former to its name, it well may be that the Horizon Spill will be the first step to the USA becoming the FUSA as Orlov predicts. But in this article he just runs the comparison of the events themselves. Among other comparisons he writes "The political challenges, in both cases, centered on the inability of the political establishment to acquiesce to the fact that a key source of energy (nuclear power or deep-water oil) relied on technology that was unsafe and prone to catastrophic failure."
Heading Out said:
Hate to quibble, but I think they cut off square
http://www.deepwaterhorizonresponse.com/go/site/2931/
(video ROV_2 at Oil Spill Leak.wmv)
n.b. it says "Preparing Drill String for NWC Overshot Valve" at 0:11
and capped off the end of the drill pipe, not the riser itself.
From the picture on the bad diagram of the leaks,
(like here: http://moreminimal.com/2010/04/oil-leak-worse-than-estimated/ )
the leak out the end looks like a drill collar,
and it NOT yellow like the riser pipe or doesn't have all the side pipe like the riser.
more video at: http://www.youtube.com/user/DeepwaterHorizonJIC
and at:
http://cgvi.uscg.mil/media/main.php?g2_itemId=46
but I cannot get the right plugin figured out for these.
Won't the (&*&^%$ gummit people use open standards!?!?!?
MORE - EDIT
found the BP press release:
http://www.bp.com/genericarticle.do?categoryId=2012968&contentId=7061856
5th paragraph:
video of capping pipe: http://www.youtube.com/watch?v=CH4I1a5vg3w
The best drawing yet of the situation:
http://www.bp.com/liveassets/bp_internet/globalbp/globalbp_uk_english/in...
This BP drawing clearly shows the difference between the riser (thick white pipe)
and drill pipe (thinner black pipe),
and why there are two openings in the sides of the dome.
I note the two leaks are barely visible, and the surface of the water is nice and blue. ;-)
Lots of detail on the ROVs and BOP stack.
This pic and more at:
http://www.bp.com/sectiongenericarticle.do?categoryId=9033571&contentId=...
The Helix Q4000 is an interesting beast.
http://www.helixesg.com
http://www.helixesg.com/EnergyServices/WellOps/Assets/tabid/154/Default....
One of the most informative yet.
ROCKMAN, please read this and comment, it is somewhat contrary to your explanation:
"The four-story, 100-ton container was positioned slightly to the side of where it needs to be placed to capture the gushing crude. Workers operating a crane 5,000 feet above the muddy sea floor were making sure the final placement would be precise so that the massive chamber completely covers the leaking pipe with a snug fit to the seabed."
http://www.nytimes.com/2010/05/08/us/08spill.html?hp
So please comment about the "snug fit to the seabed".
Maybe this is just more media failure.
The "dome" was not on the bottom when this was written - it might be now.
It was hanging off to the side of the landing area about 200 feet off the bottom. This is standard procedure. You never lower the load over a BOP or other structure just in case something goes wrong. You sure don't want to drop it on the BOP.
From this point on everything will be done at double slow speed. They will take hours to slowly lower it and move into exact position and then gently lower it to the seabed and let it settle into place.
I think this was written some hours ago and the dome may be landed by now.
2nd question - "snug to the seabed"
I doubt very much the reporter is even close to understanding the implications of sealing the dome to the seabed. It certainly needs to be "snug" to the seabed so that is stable, but there will be some designed feature that will allow the pressure to equalize between the interior and exterior of the dome.
m -- I don't recall my statement but I do babble on quit a bit. I did have doubts about the ability to guide the structure very well but it sounds as though I greatly underestimated the boys.
Snug fit, eh? That I can't really speculate about but I do know the bottom is very soft out there. But what is the effective weight of the box on the bottom and is it not being supported at all by th cables?
Bottom line they may well be on the verge of proving my pessimism wrong.
Series of failures led to Gulf oil rig explosion, BP probe shows
thanks, both of you
& pardon me for attributing Shelburn's comment to Rockman
I'm enormously flattered
Gulf oil spill could reach Louisiana Offshore Oil Port next week
Here it is again:
"Workers operating a crane 5,000 feet above the muddy seafloor were trying to place the chamber in such a way that it completely covered the leaking pipe with a snug fit to the seabed; otherwise the operation could be a failure, Doug Suttles, BP’s chief operating officer, said at a news conference here. "
http://www.nytimes.com/2010/05/08/us/08spill.html?hp
"The plan is to sink the 98-ton containment dome into the soft mud surrounding the leaking wellhead, creating a seal."
http://magblog.audubon.org/containment-dome-hovers-over-leaking-wellhead...
Perhaps Suttles is misquoted?
Perhaps Suttles does not know?
Fascinating.
Just wondering -
if there were a seal to the seabed, might it be possible to control the flow volume up the pipe with valves so as to prevent sucking up the muddy bottom?
I have no experience at all this area, just an old obsolete engineer (everything I ever learned to do in college is now done by computers). So please don't be insulted, I am not trying to argue with you.
When they first showed pictures of the device, the pipe door was well (3-4') above the "wings".
I commented that it was going to cone water like hell and I don't know why its not even with the mudline.
Now it appears to be.
If you have ever drained the water off the bottom of an oil tank using a 24 on the bottom valve, you understand coning. Trying to manage it with a valve 5,000' away with a 3,000 GOR fluid... good luck.
FF
3000 gor ? what is the reservoir temp and oil gravity if you know.
I haven't seen it posted here yet:
There is a very detailed account of what caused the explosion and some of the people involved (BP Executives were on board at the time) at the CBC.
http://www.cbc.ca/world/story/2010/05/07/oil-rig-blast.html
interesting. it seems the associated press had some trouble with the terminology:
what i think the ap meant:
the well was being completed as a production well ?
the hydrating cement generated a lot of heat which (may have) damaged the liner hanger ??
under high pressure, gas is much more dense than at surface conditions ?
a more coherent version here:
http://news.yahoo.com/s/ap/20100508/ap_on_bi_ge/us_gulf_oil_spill
This article is exactly the type of highly irresponsible reporting that upsets me.
I believe the original article was from AP and it has been picked up and distributed as gospel by the worldwide media.
I have read the AP article several times and tried to dissect exactly what data and facts led to this conclusion.
I’m not saying the conclusion is wrong but I think it is premature and based on very limited data. Here is what I found in the article.
A 73 year old, emotional, professor at U of Cal Berkley is being quoted as the ultimate authority. Is the fact that he is 73 and emotional a factor – probably not. Are his credentials good – up to a point.
He has a solid background as a civil engineer in offshore structures and pipelines; in fact I think we may have crossed paths back in the late 70s, early 80s. But in his resume at U of Cal there is no indication of downhole experience or expertise. In fact, his educational background and offshore experience parallel mine but he was at better schools and more cerebral with less grunt work.
http://www.ce.berkeley.edu/~bea/about.html
And I certainly don’t have the background to make authoritative statements about what happened to the well.
As near as I can follow from the AP article his entire source of information was “portions” of three interviews from people who were on the rig which “were described in detail”. There is NO indication that he had any access to well data. It does not identify who these interviewees are, their job descriptions or even the thrust of the interviews. They could have been cooks or consulting geologists.
That he did not even have access to the original interviews is also disturbing.
It seems quite a reach to go from descriptions of “portions” of 3 interviews to a definitive statement about the cause of the blowout.
I also get the feeling that he is focused on methane hydrates. My experience is that methane hydrate people fall in two groups. (1) Those who believe that methane hydrates are like the Bakken shale and if TPTB would just give us access it would solve all American energy needs within 6 months, and (2) those who believe that methane hydrates will cause deepwater blowouts.
I shouldn’t lump those two categories together as the second group is at least working from a scientific basis.
It is possible that methane hydrates are the root of the problem but I think it is MUCH too early to make that assumption based on the minimal information available.
And I believe the media is irresponsible to do so.
"A 73 year old, emotional, professor at U of Cal Berkley is being quoted as the ultimate authority. Is the fact that he is 73 and emotional a factor – probably not. Are his credentials good – up to a point."
if his age and emotional status are relevant, may we say the same about yours?
"I also get the feeling that he is focused on methane hydrates."
that sounds like you're building up a straw man to knock down, eh? arriving at conclusions without complete information as well, exactly what you accuse him of. attack the information, not the messenger, and i'll give your reply more credence.
New details on Top Kill idea and "Macondome" from Upstream Online:
http://www.upstreamonline.com/live/article214534.ece
Check out Upstream daily - they have had reliable, timely, and technically savvy reports every day.
In particular, here's some additional info on the Macondo oil:
The oil spill could force closure of the Louisiana Offshore Oil Port next week, authorities said Friday. The port, known as LOOP, is one of the leading facilities for imported oil, handling up to 1.2 million barrels a day and feeding half the nation's refinery capacity. Tankers too big to enter the Mississippi River pull up and hook into a pipeline system that sends their oil to onshore refineries. Current projections show the oil spill from the Deepwater Horizon disaster could reach the port next week, said Sale Sittig, director of the Louisiana Oil Terminal Authority, an oversight body for LOOP.
link
From the New York Times Green section:
3:59 p.m. | Updated Officials for BP on Saturday encountered a significant setback in their efforts to attach a containment dome over a leaking well on the seabed of the Gulf of Mexico, forcing them to move the dome aside while they evaluate find another method to cap the crude oil flowing into the Gulf since April 20.
Officials discovered that gas hydrates, ice-like crystals, had built up inside the 100-ton metal container. The hydrates tried to make the dome buoyant, preventing it from being effective.
“I wouldn’t say it has failed yet,” Doug Suttles, BP’s chief operating officer, said at a news conference in Louisiana, “what we attempted to do last night hasn’t worked.”
They lifted the dome off the well and placed it on the seabed.
BP officials said they had anticipated a problem with hydration — but not this soon in the operation. Since last week they had been cautioning that this type of procedure had never before been attempted at 5,000 feet below the surface.
The news on Saturday came as BP has struggled to find any method to stem the majority of the oil, leaking at least 5,000 gallons per day.
For now, they have put the dome 650 feet to the side of the leaking well, “while we evaluate options,” Mr. Suttles said.
Added part of the same quote farther up before I saw your post.
A few questions about gas hydrates... if someone has the time.
At what depths do they typically occur relative to the mudline?
Are they observable on mudlogs or OH logs (and what curves)? I would assume they should be easily recognizable barring any invasion issues.
When do operators in the deep water GOM typically call in mudloggers?
What is typically the top of the OH logged section?
Is their concentration sporadic and unpredictable, or is there a cyclicity to their occurrence?
Aren't they common in the deep water GOM, and if so, given all the wells drilled there to date, what is different about their occurrence in this particular well?
Someone please tell me they aren't trying to pump this containment box by suction alone. I have been on rigs where no one understands it is futile. Please tell me there is a submersible pump.
There really is not much need for artificial lift or at least not much need for lift to establish flow at some rate. Oil being of lower specific gravity will rise to the top of the dome and into the tubing / drill pipe to the surface. It will pretty much flow on its own, particularly as gas starts to come out of solution higher up in the string of pipe. Still I suppose that swabbing a time or two might be helpful in getting things moving and a REDA might goose up the flow.
That should work for liquids. My understand at this point is that the sea temperatures are causing the [free?] gas escaping from the well to interact with the seawater to essentially freeze and thereby form hydrates. Although at some pressure and temperature these hydrates would turn back into a gaseous state [higher up the pipe if they made if that far], it is the hydrates clogging up the plumbing that is the current challenge.
My apologies for over simplification. Once you get past simple I am pretty much out of theories.
It's really good written and I fully agree with You on main issue, btw. I must say that I really enjoyed reading all of Your posts.
Background Check
Thanks. I have been involved a little with some onshore exploration and production but never anything remotely like this situation [mercifully so]. There are some real experts on The Oil Drum and I am here to learn from them and contribute when I can.