Posted on 06/25/2010 12:06:38 PM PDT by Ernest_at_the_Beach
Posted by Gail the Actuary on June 25, 2010 - 10:30am
This is a guest post from Oil Drum commenter shelburn, who is a retired manager for an offshore underwater service company. Shelburn also wrote a previous guest post related to the oil spill. - Gail
In this post, I would like to respond to a long comment made by DougR a few days ago, that has received a lot of publicity.
First, I will say that in one area we are in complete agreement. BP and the USCG have been less than forthcoming, and in doing so have hurt both themselves and the general public as all kinds of wild rumors and technical misinformation abound. Some of this misinformation results in harm to individuals and businesses as people suffer increased stress and tourists cancel vacations.
In this information vacuum it is easy to make wrong assumptions that lead to mistaken conclusions. It can be made worse if you have some degree of technical knowledge and verbiage and use that to make a case for a scenario that doesn’t pass muster with actual engineering analysis but sounds highly authoritative to many people, some TV commentators and various politicians.
What eventually will happen is that the blow out preventer will literally tip over
DougR has made a case that he expects the BOP to tip over. He seems to base this on the following information.
1 – The well is leaking into the sediment below the mudline and that is undermining the foundation holding the BOP upright.
2 – In support of that theory he cites that BP cut off the broken riser to relieve pressure on the well.
3 – Currents are pushing on the BOP stack.
4 – He seems to believe the inclination or tilt of the BOP is increasing.
5 – The BOP, riser and well casing are eroding from the inside due to sand erosion further weakening the structure.
He weaves a visual picture of a 450 ton BOP waving around a hundred feet high supported by a thin piece of liner or well casing. Given that description it is understandable that people will believe the BOP is in immediate danger of collapse.
Looking at this from an engineering view point and using real data instead of conjecture and hyperbole I come to a much different conclusion.
The BOP is not in danger of tipping over.
Let look at each of his points.
1 – His theory seems to be that the well is blowing out the side about 1,000 feet below the mudline. I can understand, given the sparse and misleading information from BP and the USCG, how you could come to that conclusion. But let’s look at the actual make-up of the casing that supports the wellhead and the BOP. Here is the data:
http://www.energy.gov/open/documents/3.1_Item_2_Macondo_Well_07_Jun_1900...
First a 36” casing, up to 2” thick was put down. It extends from the mud line to 255 feet down, as tall as a 25 story building.
Next a 28” casing was run from the mudline to 1,150 feet down, almost the height of the Empire State building.
This was followed by a 22” casing from the mudline 2,870 feet down, twice as deep as the World Trade Center was high.
All three of these casings were completely cemented together and they form a very solid base which is what supports the BOP. I won’t detail the casing string below the 22” but is in the above pdf.
It is hard to envision any way the well would be able to leak out in the sediment between the mudline and the end of the 22” casing which is over a half mile down and well into formations below the mudline. At 1,000 feet there is a 1” thick pipe (the 22” casing) which is 100% cemented to another thick pipe (the 28” casing) which in turn is 100% cemented to the formation. Not much of a leak path there.
The immediate (first 1,000 feet) of well structure that remains is now also undoubtedly compromised.
There is no evidence that the foundation holding the BOP is being undermined or the upper portion of the casing (first 2,870 feet) is damaged. If you watch the leakage from under the LMRP cap you can see the oil and gas immediately start rising up at a pretty good velocity. If there were any oil or gas leaks anywhere near the BOP it would be very obvious as the leaks would look very much like the leakage from the cap and they would be quite visible as they flowed up around the BOP.
There are also occasional video shots of the lower part of the BOP and there is no sign of any seabed disturbance or subsidence. It looks pretty much like the earliest photos BP released.
The well pipes below the sea floor are broken and leaking
What may be helping to confuse the situation is that there are two more concentric “pipes” that run from the wellhead area down into the well.
A 16” casing string is suspended about 160 feet below the mudline and runs down to over a mile below the mudline. This piece of casing is also sealed to the 22” casing and hangs down from there. The “annular” space is inside the 16” casing between it and the liner.
A 9-7/8” liner was installed from the mudline to the bottom of the well. This liner reduces down to 7” before it reaches the bottom. It was through this liner that the well was expected to produce oil and gas.
The 16” casing has three rupture/burst disks subs installed and one of those is at about 980 feet down. It was this “disk” that Admiral Allen was referring to when he said it “failed”. This would indicate the “well pipes below the sea floor are broken and leaking”. But a rupture of that disk does NOT leak directly into the mud. It leaks inside the well casing.
The leak would have to migrate down to the bottom of the 18” casing - 3,902 feet below the mudline before it left the well. I expect that BP thinks they may have underground blowout at that level, which would leak into another formation, not up to the surface unless the cement jobs at the 18” casing or the 22” casing were also bad and those were fully tested and used.
DougR also supports his theory of downhole leaks by stating:
80 Barrels per minute is over 200,000 gallons per hour, over 115,000 barrels per day...did we seen an increase over and above what was already leaking out of 115k bpd?....we did not...it would have been a massive increase in order of multiples and this did not happen.
But three paragraphs above he contradicts himself stating:
Early that afternoon we saw a massive flow burst out of the riser "plume" area
and
Later on same day we saw a greatly increased flow out of the kink leaks
2 – DougR says BP cut off the riser to relieve the pressure but the timeline of the events indicates otherwise. BP had released the design of the LMRP cap well before they started the Top Kill.
If BP had thought they had a leakage problem requiring a pressure reduction, they would never have attempted a top kill. So the claim that they cut the riser to relieve the pressure doesn’t fit the facts--it fits the already announced plan to cut the riser and install the LMRP cap.
3 – There is very little current at 5,000 feet. There may be other forces acting on the BOP, like gravity, but the currents are minimal. It is easy to verify this just by watching the video of the oil leakage.
4 – DougR’s claim is that the inclination of the BOP is increasing. There is no evidence of this.
Early discussions on TOD when BP released the first pictures talked about the fact that the BOP to well head connection appeared bent and the BOP looked tilted. The pictures at that time (very bad quality) seem to show a bend between the base of the wellhead and the bottom of the BOP. I haven’t seen any evidence that this tilt has increased over time or that there is any less mud at the wellhead.
There is a good reason why the BOP wellhead connection could be bent and weakened. For over a day the DWH was without power and the 50,000 ton rig was anchored to the wellhead. The movements of the rig in the surface currents would have put a huge strain on the BOP stack.
Also, when the rig sank and the riser bent over it would also have put stress on the BOP. But the riser doesn’t weigh as much as most people would think as it has floatation on it.
It would be a reasonably easy exercise, if you have all the data, to calculate the force that bending the riser would impart to the BOP and the well head. I’m sure that BP did that calculation and it didn’t deter them from proceeding with the Top Kill.
The LMRP has a flexjoint where it connects to the BOP. I believe that flexjoint is designed to tip up to 7.5 or 10 degrees. Normally the LMRP is under some tension from the riser which tends to hold it straight. Without this support from the riser it will always tip to one side. So the LMRP will always have a substantial inclination, by design.
you may have noticed that some of the ROVs are using an inclinometer...and inclinometer is an instrument that measures "Incline" or tilt. The BOP is not supposed to be tilting...and after the riser clip off operation it has begun to...
The ROVs have been checking the bullseyes regularly, before and after the riser was cut. The box that DougR thinks is an inclinometer is likely some other instrument, probably ultrasonic. That would be backed up by another poster’s observation that they had been cleaning the area where the box was being used. They could be checking the wall thickness at that point or trying to determine fluid flow. Both are more likely that an inclinometer reading.
5 - Erosion
I am convinced the erosion and compromising of the entire system is accelerating and attacking more key structural areas of the well, the blow out preventer and surrounding strata holding it all up and together.
I‘m not sure if DougR is referring to internal pipeline erosion or external foundation erosion and I may be doing him a disservice but there has been enough other discussion about internal erosion to try to correct some misconceptions.
When we have been talking about erosion we are talking about small restrictions that have been eroded where the oil flow has to pass small spaces. The most dramatic example was the increase in the leaks at the riser kink. They started at almost nothing and grew dramatically over time. A similar process was occurring inside the BOP.
There are a lot of variables that effect erosion but the biggest is velocity. The only place that there is erosion in this well is where there are tight restrictions which have high velocity and large pressure reductions. These seem to be inside the BOP and the riser kink when it was still there. The original cross section of the leak path was probably less than 0.20 sq in. With the very high velocity this restriction would have eroded very quickly. The five fold increase in the flow estimate in the first few days of the spill would be consistent with this theory as is the continuing increase in flow estimates. As the restriction enlarges the pressure drops and the erosion slows down. This is also consistent with various pressure readings at the bottom of the BOP, dropping from the “8,000 to 9,000 psi” to 4,400 psi on May 25.
The velocity inside the casing, liner, body of the BOP and the riser is relatively low. I doubt that it would be possible to detect the erosion on the casing or riser with the naked eye. It would take years of flow before there would be enough structural damage from internal erosion to cause any problems.
This is especially true for vertical or near vertical piping. In a horizontal pipe sediment can drop to the bottom and over time wear a groove on the bottom of the pipe, which is not the case here.
All of these things lead to only one place, a fully wide open well bore directly to the oil deposit...after that, it goes into the realm of "the worst things you can think of" The well may come completely apart as the inner liners fail. There is still a very long drill string in the well, that could literally come flying out...as I said...all the worst things you can think of are a possibility, but the very least damaging outcome as bad as it is, is that we are stuck with a wide open gusher blowing out 150,000 barrels a day of raw oil or more.
This statement brings together all DougR’s suppositions. I’m not sure if he is actually that frightened himself or if he just enjoys scaring others, but his conclusions come pretty close to fear mongering.
Besides painting a picture of a completely out of control blowout (which is a true worst case), in his “very least damaging outcome” he pretty much doubles the amount of maximum flow that this well could produce according to analysis that has been presented on TOD by well experts.
If BP and the USG were more inclined to transparency, a lot of this aggravation could be avoided. You will never convince the conspiracy theorists; it is a life style they enjoy. But the MSM would not be quite as far out there if they were presented factual information, even if they couldn’t understand it.
Just doing a quick review of this long post I came up with this list of questions BP or the USG could answer that would indicate some transparency.
Have you found any seabed leaks of oil and gas?
Edit – Evidently this was answered by USCG at a press conference with an emphatic “No”. No seabed leak, no washing away of the well head foundation, no traction for the DougR theory.
Do you believe there are any leaks from the well into other formations? If so, which ones?
Has the inclination of the BOP changed? By how much?
Describe the “disk failure” at 1,000 feet.
Are you concerned about the structural integrity of the BOP?, wellhead?, the LMRP?, the casing?
Describe the formation levels.
What are the current pressure readings inside the BOP?, the historical readings?
Is there any indication of seabed movement at the base of the BOP?
What are the ROVs doing when they are looking at the seabed?
What is the little black box the ROVs place on the riser?
I could go on for pages. I understand that BP has legal reasons why they won’t comment on the flow rates or what happened to cause the blowout. But there are reams of information that they could be providing the public.
Oil spill forces Mobile Bay Ferry to shut down; no word on restart date
http://blog.al.com/live/2010/06/oil_forces_mobile_bay_ferry_to.html
They say a boom to be placed around the boat to protect it...?
Some real FACTS are needed to battle the FearMongering ......this helps....
A good find. Thorough and well laid out. The idea that the BOP was somehow going to fall over is simply ridiculous. Folks need to remember that it was strong enough NOT to break or tip when the riser pipe (and the TWO side-by-side segments of smaller piping inside it) were bent through an angle greater than 90 degrees. The force needed to do that was enormous, and yet the BOP and its anchoring well-string structure stayed solid.
When this thing started and people were calling BS on the 5000 barrels a day number they were called crazy. Turns out they were right and the leak is in (at least) the tens of thousands of barrels a day.
When people yelled about the underwater plumes that would bypass the booms to catch the oil they were called crazy. NOAA finally admited they exist only recently when in fact they were there from the start.
This pattern goes pretty much across the board; side effects of the dispersants, oil hitting the loop current, heavy security and media censorship, and the complete failures of the first few methods to cap the well.
So when these guys talk about further disaster I’m inclined to give them a listen.
H. Rider Haggard on June 25, 2010 - 10:38am
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Excellent post, shelburn. The well diagram is the best I've seen and I need to study it.
Point of interest: It's been pointed out elsewhere that dougr's alarmist comment of June 13 on TOD (http://www.theoildrum.com/node/6593#comment-648967), given publicity in Mother Jones (http://motherjones.com/blue-marble/2010/06/worst-already-true-BP-well-no...), largely duplicates one at http://www.godlikeproductions.com/forum1/message1097505/pg1 by "SHR" on June 12. So we can assume that "dougr" and "SHR" are one and the same.
Unlike dogur's comment on TOD, SHR's posting at godlikeproductions includes some photos, one of them of an inclinomoter of unknown provenance. I haven't figured out how to put pictures inline in a comment here, so I've posted that photo to http://imgur.com/j4j4C for your viewing pleasure.
Incidentally, to put another recent alarmist meme to rest, I ran through the numbers to see what thickness of sandstone it would take to cap a methane gas bubble with a pressure of 100,000 PSI. If my numbers are right the answer is 18 miles of rock. So I don't think we have to worry that 100,000 PSI may be trapped only 1.6 miles beneath the seabed at the bottom of the Macondo well.
If you read the posted article, you will see why the initial leak could have been very small, but increased greatly day by day. The article also provides factual evidence that this is what happened.
So it could well be that the first day there was only a little leak, but within days the leak became much bigger, as the high-pressure oil wore a bigger hole in the cracked riser pipe. (The article mentions a pressure at the BOP dropping in half over that time period, indicating that a lot more oil was escaping later than earlier).
Your complaint is like saying someone lied to you because they told you at 1pm that there were 2 inches of snow on the ground, but when you looked at 8pm there was 10 inches.
THX.
Will see if I can get to the article very soon. LOL.
Much appreciated.
Not necessary for the oil to "wear a bigger hole in the cracked riser pipe" to account for the increased flow. More likely is erosion within the structure of the reservoir, with the formation and widening of channels in the rock structure (which, as I understand it, is a sandstone material, and easily subject to abrasive erosion).
Eventually, the flow from the formation would reach the point at which the back pressure from the BOP/riser/etc. became the flow-limiting factor rather than the cracks and crevices in the rock. At that point, the flow should stabilize.
The guys over at "The Oil Drum" are saying that this is more likely than riser erosion.
Thanks Ernest!
When this thing started, the blowout was the result (ultimately) of a leaking cement plug in the wellbore. The actions taken would not have been a problem if the plug had held, and were a problem, because they were not correct for that situation. This plug is at least a couple of hundred feet thick from top to bottom, and the leak is a small channel through that cement. As the well has continued to flow, that plug has eroded, reducing the restriction in the wellbore and permitting increased flow.
There is no need for deceit, the numbers changed because the constriction presented by the plug opened up as it eroded.
To address another concern: The media has been doing a wonderful job of trying to panic the world with no information to speak of, and an even lesser understanding of oil drilling, geology, production, physics, and a host of other related topics.
From a liability standpoint alone, the last thing BP needs is a swarm of vessels or sircraft aropunt the site, getting run over by crew boats, having mid-air collisions, etc.
They have enough problems. With the media's typically arrgant attitude, it would only be a matter of time before some fool(s) got killed, and they just don't need that hassle, much less the possible and literal impact of a planeload of idiots colliding with a relief well drilling rig, accidentally or even intentionally.
Better to close the area to more random traffic and keep the spinoff problems to a minimum so they can focus on the problems at hand.
There are already two rigs drilling relief wells, one recovering oil from the wellhead, and another recovering oil and burning it, with the swarms of support and crew vessels needed to keep those operations going in a relatively small patch of water. When you consider the turning distances and relative maneuverability of the support vessels versus small craft, you can see the potential for disaster.
The first few methods to cap the well:
When the BOPs did not close, they were pretty much limited to recovery of as much oil as possible.
The containment dome was not intended to 'cap' the well, but to provide the means to recover the oil before it escaped into the environment--it failed due to methane hydrate formation.
The riser insertion tube was not an attempt to cap the well, but to recover oil long before it ended up onshore. As the riser was eroding and leaking, that was proving less effective.
The top kill/junk shot was a longshot, frankly, because there was no seal at the BOP. That failed, but provided the opportunity to cut the eroding riser and have a single source of oil so it could be better recovered.
The latest wellhead adapters are just oil recovery apparatus, to either recover and ship the oil to be refined (the proceeds going to a relief fund), or to burn it rather than let it go into the water. The effort has been remarkable (although BP is not getting much credit on that account): never before has such a large quantity of oil been recovered from the environment in the instance of an offshore blowout.
Continued efforts to recover oil will mitigate the amount of environmental damage done by the incident while the relief wells are being drilled, and that is happening at least three times as fast as it would have a couple of decades ago.
The loop current is a known factor in circulation in the Gulf, and should not have come as a surprise to anyone knowledgeable about the currents there (Obviously, the media were surprised).
I don't work for BP, never have, don't own their stock, but I'll risk flaming for this: They screwed up, or at least someone on the rig did, there should have never have been a blowout. They have plenty on their plate without catering to the larger-than-life egos of a media troupe which does not even bother to understand, assuming they are capable--which may be a stretch--the industry, the physics, the hardware, the basic processes, or the engineering behind either the incident or the likely solutions.
However, with understanding, with knowledge dies panic, and the latter is what the media's mission is: to foment panic so people will push for cap and trade and dumping the already empty public coffers into the pipe dream of being able to run this country off a windmill.
There are people who stand to make tremendous fortunes off of 'carbon credits' in the Chicago Carbon Exchange, fortunes which will be paid by every consumer of energy, and which will go into the pockets of the likes of George Soros, Maurice Strong, Al Gore and others, just as soon at carbon credits are required by law or regulation. Otherwise, that whole scam is just so much worthless paper. So now you know why the panic is being pushed. Trillions of dollars hang in the balance for some parties, and the American economy as well.
I figured the eroding choke in the wellbore was the flawed cement plug which leaked in the first place and failed the negative pressure test.
U.S. Asks Court to Keep Deepwater Drilling Ban
Keywords seem to have been deactivated....which really makes finding stuff tough.
AND The OilDrum has a second thread with much more conversation on the DougR commentary and all sides going at it!
BP's Deepwater Oil Spill - Response to DougR's Concerns - and Open Thread 2
Late night updates
I wish I could get on there reliably, but a series of heavy thunderstorms between me and the servers over the past week have made a mess of the internet connection I had, and it was dial-up in all its blazing glory...
Ernest, as long as people realize that the same laws of physics apply when the rig was starting to move off of a well which had been under control, and was at that time believed to be under control by virtue of a cement plug, then they will realize that restoring those same conditions at the producing formation will bring the well under control again.
Restore the hydrostatic pressure which had the well controlled, plug the wellbore.
While it is more complicated to do that now than it was with a rig, riser, and vertical access to the wellbore from the top with drill pipe, it can still be accomplished using the two relief wells. That takes some time to do, but the following should also be considered:
BP has recovered more oil from the water than anyone, ever, before it even reached the surface.
BP used dispersants to a tremendous degree, but this had been previously considered to be a good thing. Now they are under fire for doing what had been considered a preferable course of action, even though the data which claim this is a bad thing have yet to be verified.
They have invented, constructed, and implemented a series of tailor-made solutions to the logistical problems of recovering oil from the water, considered a bunch of others, and been more hindered (apparently) by our own government than their willingness and ability to do so, just as the State of Louisiana has been hindered in the building of sand berms to protect wetlands.
Government needs to either lead, follow, or get out of the way. It seems they have not done very well at any of that, with the exception of shutting down the rigs which did not have a problem. Go figure.
There are people who have much to gain for selling/fomenting/milking panic, from the soap-sellers of network news to the would-be carbon traders who stand to make a fortune from cap and trade if they can just get the lemmings to jump off that cliff, to the government people who do not have a clue what is going on but want to look effective by handing down sweeping edicts—even if they make no sense.
More liberty has been lost in the history of this country in an ‘emergency’ than at any other time. People will clamor for expedients which become policy, not just ‘for the duration’, but for so long as a ‘state of emergency’ exists, and that, by decree, has existed since WWII.
We must be ever vigillant, place events in historical context, get solid facts separated from wild-eyed (and even more subtle) speculation, and make sure the science we do apply is sound.
An impressive degree in an unrelated field does not make one as knowledgeable than a 30+ year hand with not so much as a GED who has been working hard in the patch and learning everything they can about it—I know one company hand who can run rings around most degreed drilling engineers because he learned everything he could about as much as he could over those 30+ years, and I’ll work with that man over a dozen PhDs, on location, any day, where my life (and the rest of ours there) may depend on his ability to identify and remediate any problem before it becomes critical.
Keep in mind, too, that the rig was still burning when the conspiracy-hounds popped out of the woodwork, teeth bared, and started in with everything from North Korean midget subs to self-sabotage, but the bottom line is that someone appears to have made a series of errors in judgement which led to the disaster. Had those errors not been made, eleven men would still be alive, BP would be releasing information on a tremendous new field discovery, and America would be a little closer to energy independance as a result, instead of the government trying to manipulate a crisis into greater dependance over the long haul.
There are those who would nuke the well and those who would ‘nuke’ the economy, and the end result of either action is simply that we will end up sending more money to those who would nuke the country.
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The picture is a "bullseye", one of several the ROVs have been checking since the videos were available. They are standard equipment on subsea wellheads, BOPs and LMRPs.
The inclinometer that DougR referenced was a "black box" the ROVs have been pressing against the side of the BOP/LMRP/riser.
I was thinking about the methane bubble. It seems all we have to do is drill 100,000 feet into a 100,000 psi formation and then we should have all the NG necessary to sustain our lifestyles and BAU for the next hundred years.
Lets spud tomorrow - drill, baby, drill.