128 comments on Of Oil Supply trains and a thought on Ain Dar
Comments can no longer be added to this story.
| Show without comments | PDF version
128 comments on Of Oil Supply trains and a thought on Ain Dar
Comments can no longer be added to this story.
| Show without comments | PDF version
Search The Oil Drum with Google
Support The Oil Drum
Recently on TOD:World
TOD:Campfire
- What "Lower Consumption" Means
- Tricking and Treating the Future
- Meeting Energy Decline Part-Way - Potatoes?
TOD:Europe
- The Future of Nuclear Energy: Facts and Fiction - Part IV: Energy from Breeder Reactors and from Fusion?
- The US stimulus and "green jobs"
- EROWI - energy return of water invested
TOD:Canada
- In this house, we obey the laws of thermodynamics!
- The Round-Up: October 24, 2008
- Compressed Air Energy Storage - How viable is it?
TOD:Australia/NZ
- The Bullroarer - Saturday 7th November 2009
- The Bullroarer - Friday 30th October 2009
- Details of Solar Flagships Released
TOD:Net Energy
Blogroll
Energy Sites
- The Coming Global Oil Crisis
- Die Off
- Dry Dipstick
- Energy Bulletin
- From the Wilderness
- Life After the Oil Crash
- Peak Oil Crisis
- Peak Oil News and Message Boards
- Powerswitch
- Rigzone
- Matthew Simmons
- Wolf at the Door
Environment & Sustainability Sites
- The Daily Green
- EcoGeek
- Eco Street
- Green Car Congress
- Green Options
- green.alltop.com
- Gristmill
- RealClimate
- Sustainablog
- Treehugger
- WorldChanging
Blogs
- The Big Picture
- Casaubon's Book
- Cleantech Blog
- Clusterf
k Nation (Jim Kunstler) - The Cost of Energy
- David Strahan
- The Energy Blog
- Entropy Production
- European Tribune
- GraphOilology
- Health After Oil
- jeffvail.net
- Mobjectivist
- Peak Energy (Australia)
- Peak Energy (USA)
- R-Squared
- Resource Insights
Finance & Economics Blogs
- Calculated Risk
- The Crash Course
- Ecological Economics
- Econbrowser
- Environmental Economics
- Infectious Greed
- The Mess That Greenspan Made
- Mish's Global Economic Trend Analysis
Organizations
Peak Oil Primers
Beware email scams!
Beware email scams claiming to be from this site. We do not have any job openings. If anyone contacts you about a job at The Oil Drum, do not reply to them, and definitely do not give them any personal information or send them money. Read more here.
“Government is too big and too important to be left to the politicians.”
—Claire Huchet Bishop
User login
Contact
- Content: editors at theoildrum dot com
- Tech support: support at theoildrum dot com
Personnel
- Editors: Nate Hagens, Gail the Actuary, Prof. Goose
- DrumBeat Editor: Leanan
- Contributors: ace, Engineer-Poet, Heading Out, jeffvail, JoulesBurn, Sam Foucher, Robert Rapier
- TOD:Campfire: Glenn, Jason Bradford
- TOD:Europe: Chris Vernon, Euan Mearns, Francois Cellier, Jerome a Paris, Luís de Sousa, Rembrandt, Rune Likvern, Ugo Bardi
- TOD:Canada: benk, Libelle
- TOD:ANZ: Big Gav, Phil Hart, aeldric
- Emeritus: Stuart Staniford
- Technician: Super G
License
This work is licensed under a Creative Commons Attribution-Share Alike 3.0 United States License.
GAIA Host Collective
Hi, HO. Here's hoping you're doing well.
I've got a source, a very prominent petroleum engineer (now retired), who kindly reviewed the SPE paper Stuart found and that you reference. I'm not ready to release the details — indeed, I don't have them all yet — but the upshot of his reading about North 'Ain Dar is this — what's all the fuss about? He expressed some surprise that SPE had even bothered to publish the paper since, I assume, he found little of interest in it.
I'll be publishing on this when I have all the data & interpretations I need. However, I myself was pretty convinced by the paper, especially the graphs showing how waterlogged the field was becoming. But, then I thought to run it by some people who know what they're talking about. So, mea culpa.
I think this should serve as a general warning to people here at The Oil Drum who have been especially eager to jump to conclusions about Saudi production, or have come up with some strange interpretations of the public record (what there is of it). This strikes me as grasping at straws.
It is hard to live with uncertainty. There's a lot we don't know about Saudi production. We all want to come to a conclusion. But sometimes, we can't.
best,
Dave
I can't comment on the expertise exhibited in these articles.
However, I do believe that it is likely that KSA will have to demonstrate some of that reserve production capacity this summer...so I guess we will have something to discuss as a group then. Perhaps with a little more certainity, one way or another.
Hi, Dave, glad to see you here!
My take on the paper were that it had three points of interest, the first of which was that they weren't using the rigless water shut-off (WSO) more frequently (this is where they seal the bottom part of a well that goes down vertically into the partially flooded zone where the water flood has reached, so as to reduce the water make in the well).
The second was that they had not started to use MRC in North Ain Dar yet - though they have started putting in the wells, and bearing in mind that the paper was written a while ago. Interestingly they had also put in the control valves on the laterals, so that they could control extraction as the water came nearer the well horizon.
The third was that (and this was partly why I made the calculation) it seems to suggest that in 15 years the field will be over.
There were some technical points also that were interesting - vide the success rate of the WSO, and the fact that they have been using more conventional horizontal wells (of the type I just illustrated) to revive some of the "dead" wells.
Dave,
I don't mean to quibble but your post says absolutely nothing about why Stuart's interpretation of the Saudi information is wrong. All you've done is cast an unspecific aspersion without any data other than an unnamed source with unnamed conclusions. In the computer world this is called "FUD" (fear, Uncertainty and Doubt) and is deeply, deeply frowned upon.
I'm sure you have interesting information on hand but please refrain from posting until you are willing to share.
Thanks,
Gary
I have things to do, and won't be hanging around here today. But, I said
And I will do this, so stay tuned. I'm sorry if you think my giving everyone "a taste" of what's forthcoming is inappropriate.By the way, just who is spreading "Fear, Uncertainty and Doubt" about Saudi Arabia's oil production? It isn't me. You might examine your own confusion around this point.
Dave: if you can get experienced people with no conflict of interest to discuss the issue in detail publicly, that will be valuable.
Did you get an email about demand/supply?
Subject: Saudi Oil Production
Even if there is a conflict of interest, but it is open and declared, then I'll be very interested.
But I do agree that it does little good to use an anonymous source to cast doubt on Stuart's and Euan's work. It's no answer to say that Stuart et al are doing the same: they laid out their case -- whether one finds it conclusive or not is a separate issue.
I'll send you some mail.
"I don't mean to quibble but your post says absolutely nothing about why Stuart's interpretation of the Saudi information is wrong. All you've done is cast an unspecific aspersion without any data other than an unnamed source with unnamed conclusions."
Dave does this all the time, and what he does produce in the end tends to be questionable and biased, doesn't actually address the issue or remains ambiguous.
I guess we should just all trust the professionals in the oil industry to keep production rising and prices stable, huh? I'm sure they all know what they're doing and we'd never see any problems with our energy supply. Oh, wait...
Stuart-
I am looking through your "nosedive" topic to see how much net oil you are missing with the additive effects of the new projects.
I think the after breakthrough cut in Ain Dar/ Shedgum should be about 90% water... so you should be missing 1.7 MMBOPD less the new oil on the SA total curve.
Production in Ain Dar/Shedgum is now 300,000 BOPD and 2.7 MMBWPD... from 2 MMBOPD and 1 MMBWPD in 2003 if the water has risen to the top of the crest. Until someone shows me different, I find it hard to see any other way.
No doubt confirmed by the announced export cuts.
If it helps I did a bit of digging into oil consumption in the KSA it looks to me like the numbers could easily be low.
By about 200-500kbd.
I sent the info to WT. So if your seeing say 2GB of oil missing it could have well gone into internal consumption.
I could find nothing that would justify the low average oil consumption for KSA compared to Kuwait for example.
The US is at like 0.08mbpd per million
And Kuwait is at 0.12mbpd per million
If you plugin 0.10 per million for KSA you come up with 2.4 mbpd.
The above is the historical flood front velocity in North Ain Dar.. it appears to be moving at 4.6 ft/day.
This cannot be the rate of vertical movement (the field would have watered out in 250 days) .... so it must be the horizontal movement towards the crest (or approximately east and west on both sides of the North South structure).
What we seek is the vertical movement associated with this horizontal movement. This is related to the dip angle of the structure. It appears from the Greg Croft structure that the dip angle of North Ain Dar is about 3 degrees, I have a reference which says it is 5 degrees.
But 3 degrees is the most conservative, and at this angle, things happen vertically at 1/20th the rate of the horizontal, at 5 degrees, it is 1/11th .
Now, it appears that we have a cut-off date of 1/1/04, so it has been about 1185 days since the cross sections of the water level in that reservoir were effective.
At a horizontal rate of 4.6 ft/day over 1185 days, what water front has converged a distance of 5450' on both sides towards the crest of that structure.
So, the water level has moved up 237 feet since that cross section in the paper was published.
I think the Western cross shows a water level on 1/1/04 of -5,900', based on a vertical scale off of the 1940 picture with the original water oil contact.
Now if I'm correct, the current water front is -5,900 + 237 = -5,663'. If you or your friend look at the Greg Croft structure, how much of that reservoir is left water-free??
Note that through the saddles between North Ain Dar, South Ain Dar, and Shedgum, all areas spill into each other and we would expect gravity equilibration. So the water level is likely consistent between all three. Now if we have 2 MMBOPD which is going to no water free (dry oil) area, could that not result in some production problems??
Look at the wet area % contribution graph and the oil production water cut curve for North Ain Dar. Note that if you factor out the increasing dry area contribution and take into account the 100,000 BOPD loss in production for the area, the true water cut in the wet area is 65%... despite all the horizontal schmontel WSO umbrella plug BS the prior historical trend in water cut behavior continued unabated.
You went from 42% water and 90%+ wet area in late 98 at 600,000 BOPD to 42% water 65% wet area at 500 KBOPD at 1/1/04. Do the algebra, the wet area is 65% water and plot it on Figure 1 of that paper.
And over the course of the last 3.33 years since that paper was written, the water cut in the wet area on the same trend has risen to 80.30%.
NC did a good translation for the mathematically challenged, confirmed by FF last time they talked about this:
NC on March 27, 2007 - 11:10pm | Permalink | Subthread
Fractional_Flow,
Wonderful set of information you have been posting the last few days. I have been struggling to keep up with the math posted. At the risk of sounding very stupid on this forum I will try and paint a picture of what I understand is happening in Gharwar. Helps me consolodate information and maybe it will help others.
I think 3-dimensionally and it seemed obvious to me after your's and Stuart's posts that what has happenning in Gharwar is that the water was "crowding" the oil into the top of the reservoir. The shape is a very gentle curved, elogated dome, think of just the top surface (with a bit of down curving sides) of a very large diameter pipe lying on the ground. The side go down a distance say 10-20 times the thickness of the wall. With this model only the thickness of the pipe wall contains oil.
The thickness of this wall (oil) region is very thin from outside to inside, but very thick when viewed in tangential section where a horizontal straight line would enter from the outside pass just above the inner surface and pass out the opposite side. By using water injection oil in the pipewall below this horizontal line can be "crowded" upwards from both sides where it is removed at the top.
By using horizontal wells placed at very strategic locations along the long axis of the pipe shaped field oil a constant flow of oil output can be maintained as long as the pressure is maintained and the water is below the level of the horizontal well. The Saudis can maintain essentially constant BPD from the field by capturing almost all the oil dispaced upwards by the water.
There will be mixing of oil and water near the contact point but if the rock is porous enough (and the water is injected at the bottom) most of this mixing will initially be well below the horizontal wells. Very little water/oil mixing will occur at the horizontal wells because they are reltively far away from the water front, hundreds of vertical feet and also "around the bend" of the curved wall.
All is fine until the water layer gets up into the flat, top part, of the imaginary pipe wall. At that point the water can race across the wide flat part of the pipe wall (top of the reservoir) and mix with the oil column which may be miles wide but only a few hundred feet thick. Again the Saudi's can work around this a bit by finding the high spots (after all it is not a smooth surface like our pipe wall) above the general top of the reservoir and lay in a bunch of horizontals to maintain extraction rates.
In this manner the oil is continually pushed (for decades) from the lowest part of the reservoir to the top with very little water mixed in at the well location. A very constant, high rate of extraction can be maintained that is all out of proportion to the amount of oil remaining compared to most reservoirs. This is due to the combination of horizontal wells, porosity and the unique shape of the reservoir.
The problem comes when the water finally gets to those last series of top level horizontal wells. By the time you get significant water mixed with the oil, the water % is going to increase very quickly. In my simplistic model and understanding there isn't really much oil left. It's all water below the mixed zone and that mix zone is now restricted to the very top of the reservoir.
If my overly simplistic model is even close to accurate you can't pump water in for another 30 years and get significant oil out like in Texas. All you are going to get is water, because the oil was washed out of the lower rock strata years ago.
All comments, clarifications and even hoots of derision (at my lack of understanding) are welcomed because Id like to be completely wrong so I can sleep at night.
Parent | Parent subthread | Reply | Start new thread
Fractional_Flow on March 28, 2007 - 7:39am | Permalink | Subthread
No your physical description is just about right.
The high rate of extraction up until the last possible moment is quite a reality of this type of geometry (I believe West Texas has shared some such experience).
We need someone with advanced imaged analysis capabilities to tell us everything there is to extract from the Ain Dar cross sections in that SPE paper.
Dave-
Tell your retired petroleum engineer that the impact of that paper is that if what I did above is correct or close to correct .... then 2 MMBOPD-- is essentially gone.
And I didn't correct it for contracting geometry- Stuart (and others) will know what I mean.
But I am looking for an error somewhere- it just cannot be.
"But I am looking for an error somewhere- it just cannot be."
Oh, yes it can. More important(as if this isn't bad enough news), how many other fields have used the same technology for how long? How many others are on the verge of collapse?
Thats in a sense what I'm asking in my other posts. I think I lack a perspective on Ghawar vs other fields.
This brings to mind another question; What if world crude oil production were down to 50 mb/d by 2010? What if we discovered we have just stepped off the cliff and are currently in in the freefall of a World Crude Oil Production Crash?
Cid,
This is extreemly sobering.
I'm reasonably certain that I followed how FF came to the conclusions he has. This only makes it worse. I read this mid-day and it literally sent a chill down my spine. I reread it tonight and I find that I didn't get my understanding wrong. I guess we really should be have been expecting this kind of post at some point from someone very knowledgeable, pragmatic, detailed, and willing to get the word out. I do notice a lack of credible or for that matter uncredible rebuttals to FF, this adds greatly to my fear. You can follow along, and know he is right. It has that ring of truth to it and it makes sense, friggin' deeply disturbing and unfortunate sense. I have been following this for over a year now, I think new readers are going to get a bigger shock to this kind of post. This is not good stuff.
FF's post would make sense and explain KSA's coolness toward the Bush Admin., that the US is pushing KSA and KSA is saying repeatedly that there is nothing they can do and are getting tired of being pushed to do what isn't possible. We are in the end game now.
Bush and Cheney cannot be ignorant or stupid on the topic of PO. Thier idea of handling this with the Iraq invasion will probably be looked back historically as the last nails in the coffin. I wonder if they had a chance for painful mitigation given the euphoric state of current lifestyles. I don't see people willingly powering down, and that is what's required. The people won't vote for it, and you won't get campaign contributions if ELP is your platform. Maybe later but not now and not for the last 30 years.
We live in temporary, unsustainable, high technological times, yet we haven't physically evolved into anything superior to what our most recient ancestors were. We are more advanced, better educated, have a greater understanding of many things but are still the same as they were. It's too bad I liked the startrek/starwars idea of some day long distance space travel. I see that it will never ever happen and I think that is very sad but also very fortunate for the rest of our solar system.
There was an article in Natl' Geo. about Disney in florida and how horrible the sprawl is down there. They had a comment from a dade co. commisioner "Just because we have destroyed 90% of everything doen't mean that we can't do something wonderful with the remaining 10%". We have trashed our planet. You hear people talk of limited nuclear war as if this is a solution to something. They want to mark nuclear waste sites with some sort of warning that will be able to be understood 25,000 years from now. This is the very best we are able to do collectively as a species - it doesn't really say much. "Here is the posionous leftovers from our "advanced" civilization" Oh BTW sorry we fucked up the place.
Watching how people work in groups makes the whole PO problem so very understandable. How our politicians are elected and the special interest money needed to run a campaign and the favors owed to people and companies that do not have the well being of the greater population at heart. and for what? Money for more plastic crap we don't need? More security? A way to look down thier noses at others? We are still so very primitive...
HO and FF - a heart felt thank you! Looks like we had better get prepared, this can only get tough, and alot sooner than I had hoped for.
Best of luck to you guys.
D
Thats me I assure I don't agree with the concept. But in playing devils advocate to explore the position I did not see that it was unreasonable for people to take this option.
I certainly don't agree with it in any shape or form.
Hi m,
re: "...playing devil's advocate...I did not see it was unreasonable..."
I had an exchange (began w. my reply to bunyon) w. Cid, which may also apply to what you say here. If you get a chance to read it, I'd appreciate it. http://www.theoildrum.com/node/2375#comment-169763. (and if you could also read down to my next reply. Thanks.)
Darn. I just wrote a response and lost it all and don't have time to re-do it.
Bottom line? You can't reason with this type of testosterone driven male thinking because it has NOTHING to do with reason. It IS a "failure of imagination and heart" as you so eloquently put it, but you will never be able to make them see that side. In simpler terms, it's that Alpha Male Syndrome and it dooms mankind (like the Chimp said). When was the last time we elected a nerd? As far as I can tell, every male politician is an Alpha Male. Our leaders are Alpha Males to the extreme and the solutions they choose will undoubtedly be very bad.
Cheryl
George Bush an Alpha Male? HA HA HA HA HA HA HA HA(falling to the floor)HA HA HA HA HA HA HA HA... ROTFLMAO
How about Nancy Pelosi for Alpha Female?
Thanks, Cheryl,
There is something to the idea that people approach things differently, and men and women often seem to.
In my post, I intended to discuss the ideas of reason and logic in relation to the argument (I mean "argument" in the sense of rhetoric - or a justification.)
I may not have said it as well as I could have. There's an inherent problem with the argument itself. (IMHO). Though it's quite good to take a look from "inside" what appears to be an unreasonable stance, in order to understand it, my
point was simply that the logic doesn't hold, as far as I can see. There's a kind of insularity to it.
It's difficult to talk about things like this, especially when we have a format where we tend to drop things after a day or two and it's hard to "finish" a conversation.
I was asking (and would still be interested) to see if the argument I presented was at least laid out well. Did Cid agree it represented his view?
Would memmel agree it is a fair re-statement of what he was looking at as "Devil's Advocate"? In other words, does the argument, just to begin with...represent the "Devil's" position, as memmel sees it?
I'm a little confused about whether memmel is/was referring to:
1) using nuclear weapons (and we may as well include conventional weapons) as "trade items" or
2) about the idea of reducing the population (or some part of it) in this way.
3) (Or both.)
In terms of the trade concept, Chalmers Johnson has written at length about this, as have others. If I may quote Johnson from memory "The US is the only empire in the history of the world to arm its colonies."
I believe memmel had another reply to his concern as well.
On the practical side, I wanted to encourage people to get in touch with some of the people who now work (actively) to prevent nuclear war. This might be a good "peak oil outreach" action item, if one is interested in some positive "networking". (www.idds.org, www.fas.org, www.cdi.org).
Memmel, I understand. There are those who view this an an option. After 9/11 there was some lady being interviewed on her way to work that wanted to use "small" nuclear weapons to get Ossama. "one or two" - " we have some don't we? small ones?" ( if I remember correctly this was the jist of what she said)
I think because of Japan and WWII there is a sense of limited use and survivability in many folks minds. I just think it would get completely out of hand.
By all means, throw in a little "X" chromosome for a slightly gentler touch and let's make it just "one or two, we have some don't we, SMALL ones?" as opposed to the Alpha Males who would choose to "juse a BIG one and just wipe them all off the face of the planet forever. Problem SOLVED." I can pretty much guarantee that the woman didn't come up with this on her own--she has been listening to the men around her, but she softened it with "small ones," which is what she has--no "female cajones" of her own (and trust me, they do exist).
No matter how advanced "civilization" becomes, humans seem unable to control, or even comprehend, their limbic instincts, which is why I'm not optimistic about the future.
Has anyone seen production figures for Burgan since the 1.7 mb/d stated in Nov 2005?
"I'm reasonably certain that I followed how FF came to the conclusions he has. This only makes it worse. I read this mid-day and it literally sent a chill down my spine."
It is interesting that as we followed it, we were able to see the conclusion it was leading to well before FF was willing to state it. That just shows he tried very hard to prove himself wrong and still didn't want to say it when he could find no where else to go.
"...he tried very hard to prove himself wrong..."
Yes, and it makes it all the more sobering. You can understand and see that he doesn't like his conclusions and would welcome someone to point out some error. I would like that as well. I just don't see it happening. Deep down you know that oil is finite and other places around the world are in undeniable decline so we are just getting another one. So, I sit here at my dinning room table wanting...what? The truth? I think I have it. The implications of PO are so staggering. I don't know what I feel, dread, remorse, defeat, foresight, understanding, motivation? People are going to be numbed by the multi-front way this hits.
Petroleum Economist (can't be sure of accuracy), was quoting 1.5 Mb/d figure in Sept 2006 for Burgan and claimed "Burgan field is maturing fast."
Yep, there she goes! Cantarell slips under the waves.
Cantarell´s daily production in February was 1.567 million barrels, an 18 percent drop from 1.912 million barrels in February 2006 and a 1.5 percent slide from 1.591 million barrels in January, according to the Energy Secretariat´s web site.
That isn't far off their projected 14% decline per year... not a good thought either way though, is it?
"You can never solve a problem on the level on which it was created."
Albert Einstein
I ran -18% for 6 years. Came up with .476 million barrels in 2013. A drop of over 2/3.
Was this part of their OPEC cut or a genuine production drop due to lack of drilling initiative or terminal depletion curve?
There is no question that Cantarell is in terminal decline. It is freely admitted.
Mexico is not an OPEC member.
My [mis-?] understanding is that it will very suddenly go to ZERO. Is this correct?
James Gervais
Near enough.
FF,
I have tried to follow you argument by referring to SPE paper 93439 and the Greg Croft Ghawar structure map.
You are the expert so I will have to assume you are right on the 5% vertical/horizontal water movement ratio - is there any equation etc you can point us to that substantiates this?
You refer to the "Western cross" - assume this is Figure 9(a) in SPE 93439?
The Greg Croft Ghawar structure map shows the high contour in northern 'Ain Dar at -5750 feet. You suggest the current water front is -5,663 feet. In other words, the water front is at the top of the structure....
The saddle area between north and south 'Ain Dar and Shedgum lies at -6250 feet, so asssuming homogenous porosity, all these areas must must have water at the top of the reservoir.
Is Figure 10 the "wet area contribution graph" you refer to? And the "oil production water cut curve " Figure 1?
What I don't understand is your statement "if you factor out the increasing dry area contribution and take into account the 100,000 BOPD loss in production for the area, the true water cut in the wet area is 65%" Can you explain how you got to that?
Also, Figure 2 of the SPE [paper appears to show a steady water cut of about 80% since 1999. I am not sure what the Y axis "Mstb/Day" is (guessing '000 barrels/day), but it shows approx 400 units of water production to 80 units of oil production per day.
According to the fractional flow curve you gave us for 'Ain Dar / Shedgum, this would represent about 58% water saturation...
I can undersrtand very clearly what point you are driving at, but I cannot follow your methodology in getting there... some elaboration would be very much appreciated.
I think we are taking a lot of what FF says as gospel truth, and it may be, but I also believe we need our "experts" to verify that they agree with FF or have some other form of confirmation here.
After all, this is pretty important information.
Look around you on this post and the previous posts. The data is all here. The math is all here. Each step has been presented and subject to "The Oil Drum" peer review. Stuart has weighed in throughout, Bunyonhead today. What 'experts' are you looking for? This doesn't have anything to do with HL or predictive modeling so Robert probably sees this as outside his domain. Prof. Goose usually sits on the sidelines and watches from his rocking chair, making a seperate post if the spirit moves him. Khebab and Engineer-Poet are probably defering to the obvious expertise already demonstrated here and would weigh in if they felt the need. No one is accepting this on faith. The case has been made. FF doesn't like the conclusion and would be more than thrilled to have someone prove the argument wrong. Both Stuart and Bunyonhead through their own analysis have supported the conclusions. Unless you are looking for a sign from heaven, you have what confirmation is available. Also, you have the fact that no one has come forward to show a flaw in the argument. We are waiting. Prove them wrong by addressing the argument directly, not by insinuation. Otherwise we already have the 'best available information'.
I guess my it is just such a hard pill to swallow when the reality of crude/gasoline prices are not showing many signs of impending spikes, US inventory data not showing horrific drops, and business as usual continuing here in the US.
I know there are signs of demand destruction in third world countries, but almost no signs here. I believe all our experts, but from the looks of what FF is saying...it is going to almost be one day, everything looks fine, and the next, news of shortages.
I guess what I'm saying above is...is there any reason for doubt in FF's data? If not, if we have all come to the conclusion that it's sound, then I think the near-term POers are correct.
Cid Yama...I just read all the comments further down this thread...I take it all back...FF is correct...and we are all fucked!!
Yikes.
It really does suck doesn't it. All I wanted to do is sit in front of my computer warm and fed for the rest of my life. My house has been paid for for years. I work at a job less than 4 miles away where I come and go as I please. Can work 2 hrs or 10 it doesn't really matter, my choice. I have the perfect life and now it's screwed.
Euan is back now and catching up and may post a dissent. Also there is a prospect of getting more meaningful input from the mysterious expert Dave Cohen referred to yesterday.
So there is still some hope that someone will show us the errors in our reasoning...
If our "hope that someone will show us the errors in our reasoning" is dependent on us getting "more meaningful input" from Euan or Dave, then we are screwed.
I've never wanted to be wrong about something as much as I've wanted to be wrong about all this.
Yeah, me too. Rather than be right, I'd much prefer to feel like an idiot in a world in which North Ghawar was not watering out while the Saudi's scrambled to cover up the fact
FWIW, I've been over the discussion between FF and Bunyonhead here in detail this evening. I kind of generally agree, with a couple of caveats:
Stuart-
You need to read about the "average water saturation at breakthrough" and the water cut at breakthrough.
You can throw the fractional flow curve away. The outlet end is either pre-breakthrough (100% oil)or post breakthrough (90% + water). Breakthrough trumps all.
And breakthrough or not breakthrough is the point of this whole discussion.
Ok, but if "post-breakthrough" meant 90% water cut, then in 2004, the wet area would have been producing 90% water cut, right? And that would imply, since 65% of the water production was from behind the flood front, that overall water cut would be 90%*65% = 58.5%. But it was 42%. So I don't see how the numbers can add up like this. (But feel free to point out how I'm looking at it wrong).
Stuart-
The "wet area" includes the well that has 1' producing 90% water and 203' producing 100% oil. The water is moving in from bottom to top in every practical way imaginable.
The only well(s) in the dry area produce 100% oil, no water.
Until you grasp the above you will not understand what a dramatic event the fillup of this reservoir is.
FF
Bunyon
Either the sine or tangent of 3 degrees gives the 1 to 20 ratio.
If the 4.6 ft/day is measured along the bedding plane use the sine, if it is referenced to true horizontal, it is the tangent. We have no way to know the reference dimension.
Note that I knocked nearly 50' of the true calculation- that is how bad I want this to not be.
You took the effort to look at the Greg Croft structure and verify what I said. You are to be commended. Now try to verify that Western Cross (figure 9a) position. The original water oil contact is -6450' ss. I have a 1951 study that has an excellent map of the WOC. Compare the thickness of the reservoir at the crest to the height above the Original WOC to determine what reservoir elevation you are viewing. Try to scale it vertically. I bet this is done 1,000 times in the next month by various people- you might as well do it now. It was the topic of my first post almost 2 weeks ago.
The reservoir appears to be thickening at the crest. It would be nice for someone to measure the thickness along the vertical grid lines and distribute it around the average of 204'.
The field was producing at 90%+ from the wet area in late 98 at a 42% water cut (it is the right scale). At 1/1/04 it produces 65% from the wet area at a 42% water cut. Aramco touts their water cut management skills but the governing equation is
Total Watercut= Wet Area % * Wet Area WC + Dry Area % * Dry Area WC
Since the Dry area WC= 0 by definition the equation becomes
Total Watercut = Wet Area % * Wet Area WC
So Aramco has controlled the total watercut by lowering the wet area %, pulling harder or drilling more wells in the dry area.
When they do this, they are sacrificing ultimate recovery to meet market demand.
ok....
I measure the total height of the cross section at about 760'
The top of the 1940 100% water saturation is approx 205' above the lowest point. I assume that is the original OWC?
Greg Croft has original OWC for 'Ain Dar at between -6430' and -6665'. Since we are discussing northern 'Ain Dar I assume we must be at the deeper end for the original OWC (ie closer to -6665' than -6430').
Moving along.... if I am correct in assuming that the 1940 OWC is the point where the dark blue (100% Sw) ends, I measure the distance from there to the top of the formation as about 555'.
This gives the top of the structure a depth of between -6110' and -5875'. Taking your original OWC of -6450', we get to -5895'. How do you know that original OWC for this cross-section is -6450'?
Looking at the Greg Croft Ghawar contour map, I think we are looking at a cross section somewhere around the northern tip of the -6000' contour.
As to reservoir thickening at the crest, I think this may be a trick on the eye caused by colour differences. It might be 5' thicker than at the bottom, certainly not much more.
You commented that "The field was producing at 90%+ from the wet area in late 98 at a 42% water cut (it is the right scale). At 1/1/04 it produces 65% from the wet area at a 42% water cut" Taking your equation TWc = WA% x WAWC%, we see that wet area water cut must have been 65% at 1/1/04, implying Sw at about 55%.
Taking your view of OWC at -5900' on 01/01/04 (my view betweeen -6110' and -5875') and your calculaton of vertical water movement of 237' to the preset day, you now get to OWC of -5663' (my range -5873' to -5638').
On your prognostic, there is no dry oil left in 'Ain Dar and Shedgum. By my guess, there may be 3 areas around the -5750' contours where there is still dry oil left in these fields. There is also potentially a very large area where the 'Ain Dar, Shedgum and Uthmaniyah fields converge around the -5750' contour that might still be dry. I guess this area at about 50 square miles.... but I have no idea whether that area is oil-bearing or not....
So, possibly the situation is not as dire as you initially thought, or, more likely, I have made a huge and obvious error somewhere.
Either way, you are right in your assertion that they have controlled the water cut by increasing the take from in front of the waterflood.
Great work.
Your analysis of the xsection confirms mine
Water oil contact data from Arab American Oil Study
Looking at the West Side Gradient, it may be down to -6,500' or so where they are at.
The huge transition is west to east and working the East Xsection now will reveal that. Are they in the same place?? Perhaps.
Note that 237' is 50' low for a 3 degree dip. That is my conservative factor. I believe the "large area" you refer to is a depression... Look at the 3d image Stewart had of the permeability field.
Thanks
FF
Absolutely right that the "large area" is a dip, contour is -6250' - what an idiot I am
Bunyon-
Don't be too hard on yourself.
If you had to run 4,600' on a 3 degree upslope... what would your final elevation be in reference to your starting elevation???
How would you figure it??
FF
About 240'? Using sine of 3 degrees=a/4600?
Just trying to brush up on my incredibly ancient trig class...
High school maths: 5.2336% of the horizontal distance travelled, ie 241'rise if the horizontal distance was 4600'
Looking at that I would SWAG original OWC at-6500', which would put it at -5945' on 01/01/04.
Using 237' since then, we get to -5708' (or -5658' with the extra 50')... so on that basis there would be very little, if any, dry oil left in AD/S.
One other point I noted. The flood front velocity appears to be decelerating substantially from 2002. Extrapolation of the linear "trend" from the last two points suggests velocity may have dropped to below 2 by now. Is this possible?
If the average velocity had dropped to 2.5 or less since 2004, this would imply a water level rise of almost 100' less than we have been discussing. Clearly flood front velocty from 2004 to present day is a very key part of the equation here.
Bunyon-
Excellent.
Work the East cross section- there is a lot less variation in the OWC data there. It appears solid.
What are the physics that would make that velocity drop... you are astute..
Certainly pulling harder on the dry oil area would have the inverse effect....
Look at the large crestal structure at Shedgum... Could that water be starting to spread across the base of that large crest during 2004, increasing the flow area and reducing the velocity.
Note the influx area (lengthwise) is always contracting as you move towards the crest of the dome.
But if the zone is thickening up at the crest, then the flux area is expanding in that dimension.
We await Aramco's update anxiously.
Why are they going to add 3 million barrel of injected water per day to this area???
FF
Eastern cross section: guessing original OWC -6650', height of structure 980'
Distance from Original OWC to top of structure - 530'
Crest therefore at approx -6120' and western edge of structure about 70' deeper at -6190'
I think this cross section is about 1.5 miles due north of the western cross section, which gives me a headache to understand why the 2004 section doesn't show a higher water saturation at the crest and west of the crest.
Probably made a mistake somewhere
Looks like the structure thickness may vary by 15 to 20'
Bunyon-
As you probably know...
the vertical exags on the 2 sections are different.... You relate the thickness of the pay at an average of 204 to the distance to the WOC. You cannot use the reference scale on one for the other.
But I believe the 2 sections are in the same place... as the water level in reference to the thickness/crest are identical... so perhaps an average of the 2 are the best we can do.
Note, however, if the interval thickness averages 204 but varies from 180 to 230 or some such things your error will be multiplied by nearly 3.
So it is difficult as hell to know for sure.
This is the ballgame... are we in the bottom of the ninth or the seventh inning stretch???
The production performance for the country, the increase in rigs, the announcement to increase water into these old areas, the acceleration of project timetables, the non-existent "heavy" oil cuts... that brought me out with this stuff after over a year.
FF
I have no idea what would make the velocity drop, physics not being my strong point....
Pure guesswork here: The 'Ain Dar crests are quite "pointed" due to the tight contours. My thought is that the horizontal flow has to slow and the vertical velocity increase assuming a constant rate of water injection.
For Shedgum with its more rounded crest I would think a similar process would occur but at a much lower rate of change.
As I said, this is pure guesswork on my part, and I am probably barking up entirely the wrong tree.
If I am right, it's a scary thought....
Think about filling a vessel with a narrow top with water. It accelerates towards the top as the volume to fill/level is less. Common sense. How could you be wrong?
N. Ghawar becoming all wet? This is what I think I read. Saw one color coded cross section a few days ago of the north end and a thin film of oil near the top becoming mixed with water. Am guessing the two anticlines have relatively flat crests and a saddle syncline in the middle. Cannot see if water injection in southern Ghawar might flow to the north or visa versa. Where there any lateral impervious zones to compartamentalize the reservoirs?
FF said:
Note that through the saddles between North Ain Dar, South Ain Dar, and Shedgum, all areas spill into each other and we would expect gravity equilibration. So the water level is likely consistent between all three.
Bunyonhead said:
The saddle area between north and south 'Ain Dar and Shedgum lies at -6250 feet, so asssuming homogenous porosity, all these areas must must have water at the top of the reservoir.
Based on measurements on the blue lines in this blowup of the Greg Croft contour map:
I make the angle on the west side as 4.4o, and on the east side as 2.3o. There would be slight variations at points north or south of here.
Indeed, what is the fuss all about. After all the Saudis have admitted that all their existing fields are declining by from 5% to 12% per year. The Saudis admitted, three years and three months ago that Ghawar was 48% depleted and that Ain Dar/Shedgum was 60% depleted. Do the math and that puts Ghawar way over the peak today and Ain Dar/Shedgum deep into the geriatic stage.
And realizing the Saudi predilection for painting everything in the very best possible light, I think we can safely assume that Ain Dar/Shedgum and the rest of Ghawar are in far worse shape than they were forced to admit. And if their depletion rate of existing fields are any worse than they admit, heaven help their poor souls.
So what's the fuss all about. The Saudi's are admitting things are are looking bad. However they believe that as soon as they tap into a bit more of those 260 billion barrels of proven reserves everything will be okeydokey. Of course they must locate them first. ;-)
Ron Patterson
URL, page 21, where Saudi admits to Ain Dar/Shedgum and Ghawar depletion status.
http://www.saudiaramco.com/sa/webServer/general/Presentation_Fifty_Year_...
URL where Saudi admits that all existing fields sustain a 5% to 12% depletion rate.
http://www.eia.doe.gov/emeu/cabs/saudi.html