43 comments on Saudi Arabia: An Attempt to Link Oil Discoveries, Proven Reserves and Production Data
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43 comments on Saudi Arabia: An Attempt to Link Oil Discoveries, Proven Reserves and Production Data
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Matt Simmons quoted a retired Aramco executive as saying that, in his opinion, there was no way that the Ghawar URR would exceed 70 Gb. Of course, Saudi Aramco is claiming that horizontal wells have boosted the recoverable reserves in the field, but that is what Shell though they had done at the Yibal Field, where they were expanding their surface facilities to handle an expected increase in oil production, when they were hit with an unexpected flood of new water, which is what I suspect happened at North Ghawar in 2006.
BTW, as an illustration of the conservative reserve scenario, could you post our updated Texas/Saudi graph (with 2006 and estimated 2007 Saudi data) on this thread?
The error bar on Ghawar is pretty high (almost 45% uncertainty!), even the cumulative production estimates differ significantly!
In attempting to come up with a correction for technical advancement I've come up with technology causing 50% higher extraction rates over a period of decades. Since Ghawar has been under water flood from the begining this would give a real URR of 60GB as the absolute minimum. Since the early water flood has probably also increased recovery say by 10% this gives 66 GB.
Which is inline with WestTexas's statements of 70 GB. Its my understanding that this can easily be modeled with the shock model if you add a depletion shock.
http://mobjectivist.blogspot.com/2005/11/can-we-delay-peak-by-upping-ext...
I think if you apply a few reasonable corrections for extra depletion then it will pull your URR estimates back in some. And as you can see steepens the post peak decline rates.
Note that at least in the case I showed the shock came late for Ghawar it was a early
shock and continued to date with the latest MRC well technology. That does not change the
analysis all that much.
Also it would bring the data in line with existing production but in this case the slowed declines right now are caused by technology not your reserve estimate. And the peak date is in the past and further more Saudi should be in steep decline by 2010 not just peaking.
But notice that if you do add in a technical extraction effect then you end up with reserve estimates probably being high. Especially reserve additions. Its a sort of chicken and egg problem newer technology has led to bolder reserve predictions yet has in general only increased depletion rates.
So I tend to go with the 70 GB for Ghawar and Saudia Arabia in obvious decline by 2010. And they could start down again any time within the next two years. I don't think the data justifies narrowing it down by much more but resumed decline by the end of 2008-2009 is quite probable.
Estimates for cumulative production for Ghawar (circa 2000) are already around 60+ Gb, so 70 Gb is awfully small for the URR. On the other hand, if we use the 173 Gb for the OOIP and an average of 40% recovery factor for giant fields, we get precisely 70 Gb for the URR. However, analysis produced by Euan and Stuart are suggesting that the average recovery factor for Ghawar is more likely around 60% due to the exceptional quality of the reservoir.
Khebab this is my point we are basically entirely dependent on technology.
And its a race between faster depletion rates and greater recovery.
How can we know that they will get a 60% recovery. The field is high quality but it has super K zones bypassed oil pockets etc. And furthermore we are really dependent on getting this extra 20% or a large portion of it at high flow rates.
In general the rate of production over the last several years and esp the coming ones will be very dependent on what we really have accomplished with advanced technology.
I'm very skeptical of the concept that we have both increased URR and gained the ability to get most of this extra oil out at high flow rates.
Basically todays production can be classified in three classes.
1.) New large fields ( small percentage of worlds oil )
2.) In field small field thin layer extraction mainly horizontal or smart completion on verticals.
3.) High water 90% cut what I call rock washing.
Ghawar is at the thin layer extraction phase. All my reading indicates this approach allows you to get the last of the oil out at low water cut and high flow rates for a short period of time.
Outside of tight formations not easily produced using verticals I've seen no evidence that recovery factors are higher.
Now for 3 you have two problems one the amount of oil you pushed out with water drive originally is dependent on the fractional flow of the formation along with physical cracking etc.
Ghawar may or may not have had higher recovery rates from the original water drive. I've not seen enough evidence to convince me either way on this.
Next for Ghawar the shear size of the the field makes moving to rock washing at high water cut a huge engineering project which the Saudis are not doing yet in all other fields a lot of the real URR increases are obtained at much lower production rates during this phase of the operation.
And I don't think they will unless oil remains in high demand for a long time. They are better off producing the other fields and coming back to the rock washing problem for Ghawar later.
What KSA is claiming is that the production mode of Ghawar magically moved almost 90% of the OIP.
One reason they are not in a hurry to wash rocks they don't believe they left a lot behind.
I don't buy it.
But thanks for your response I'm troubled that our future rests on our technical achievements which at least from my reading are subject to extravagant claims that don't match reality.
A lot of the work done on the oil drum really points out that the claims made by the oil industry are dubious at best. I've come to the conclusion that we have yet to fully determine how far off they really are. From what I can tell the current approaches are still giving numbers that can be up to 50% too high.
M King. Hubbert correctly predicted the peak of production for the US. He also predicted peak production for the world and a total URR of 1250 GB. Above ground factors around the peak year that Hubbert predicted of 1995 easily explain why we did not see peak production. The simplest is we hit peak production capacity but the world could not use all the oil. If you go back and try to figure production capacity around 1995 and remove the effects of preceding events like the Iran/Iraq war its obvious that the world could have hit close to 90-100mbd back in 1995.
No way in hell could we do that now.
But given technology and political factors our current high production even if the URR is around 1250 barrels is not unjustified. I'm 100% convinced that we are now able to produce a lot of the original URR estimates at high flow rates with current technology.
What I've not been able to convince myself of is that M K. Hubberts estimate for world URR is wrong. Ghawar points to the problem with even on field predictions of future production from about now on out are completely dependent on how much we have increased URR available at high flow rates.
Jeffrey, would you care to explain to our readers the difference between:
1) a horizontal well drilled into a thinned oil column in good quality reservoir late on in field life that is intended to lower water cut (e.g. N Ain Dar), and
2) a horizontal well drilled into a poor quality reservoir that may be impossible to develop using vertical wells (e.g. Haradh)
and then say if you think it is reasonable or not for Aramco to expand reserves of Ghawar in the latter case?
Of course there is some improvement in URR in the case of #2, but what will be the increase in URR from the entire Ghawar complex as Saudi Aramco is forced to produce a "poor quality reservoir?"
Why would Saudi Arabia be bothering with a poor quality reservoir if they didn't have to?
Estimates of URR involve a certain set of assumptions regarding the field itself (reservoir volume, perm., porosity, original water, residual oil), the technology to be used, and the developmental strategy. Few of those are known very well at the onset.
If the reservoir is well behaved (i.e. horizontal and vertical equilibrium is maintained), one would think it wouldn't matter if one used vertical or horizontal wells. Just phase out peripheral wells which are watering out, drill new ones updip, and drain it until all that's left is the residual oil. To get beyond that, you would need to do something to change the fractional flow characteristics.
Of course, none of their reservoirs are really well behaved in that way. With Ghawar, it is so big that it really didn't matter for awhile. Now, however, the real risk is stranding some of the oil due to uneven waterflooding. The developmental strategy is altered to mitigate that risk, employing new technologies along the way. If all goes well, they might get the original URR out after all. So, if you increase the reserves due to the technology, do you decrease the reserves before that due to the problems encountered necessitating the new technology?
Were any of their reserves (such as Haradh or Khurais) decreased after finding problems there, such as the fractures and Super-K in Haradh?
For example, this is from one of Saleri's presentations:
Abqaiq has produced more oil than were assumed to be reserves in 1950, so what was not known or assumed in 1950? What new insight did they have in the late 1970s and 1980s to justify the increase?
This is a good counter point to the technology effect and shows how it could be a large factor in the opposite direction. My best guess is what really happened with Abqaiq is addittional oil was found trapped in another level.
But Simmons has a great paper on this issue.
http://www.simmonsco-intl.com/files/Reserve%20Reporting.pdf
And another good one.
http://www.oilandenergytrends.com/ger/ger_saudi.asp
Note that if you read this second paper Oil And Gas Journal gives a reserve estimate of 64.8 for
Ghawar in the 1970's and it had been in production for some time at that point. This is inline with my estimate of 66 GB.
And of course Abqaiq at 7.5 GB note we have reason to believe the 1970's numbers are better than the 1950's these are very large fields and it takes time to delineate the field using traditional wells.
So does Abqaiq "Destroy" the concept ?
This paper
http://countrystudies.us/saudi-arabia/41.htm
Indicates to me that Abqaiq was in decline in the 1990's.
Its production profile with a URR of around 7-8 GB matches well with that of Phrudhoe Bay at 10-13GB. It's peak production was less. Also this is a old field and was under American production for a long time.
Now I've been unable to find any recent production data for Abqaiq. KSA does not seem to publish consistent per field production numbers if they do then I've not been able to find them.
To be blunt I don't believe this graph and cannot find any easy way to prove Abiqaiq could be this high given it was under American production control for most of its life history.
And whats know of its historical production fits with its estimated URR not with the one claimed in the graph when compared to similar sized fields.
Also note this paper was produced in response to Simmons work.
Another link about the paper.
http://saudioilproduction.blogspot.com/2007/04/fredrik-robelius-on-saudi...
I've read the Saleri paper in the past but cannot find a link to it now.
Overall its very optomistic.
Here is a link
http://www.csis.org/media/csis/events/040224_baqiandsaleri.pdf
And the Simmons paper at the same time.
http://www.csis.org/media/csis/events/040224_simmons.pdf
http://www.csis.org/component/option,com_csis_events/task,view/id,429/
Note the entire paper has been extensively discussed. And its not in agreement even with the results of the current posting.
I'll come out and simply say it.
The graph is pure bullshit.
I am a new poster on this site and I am definitely no expert on Ghawar, but the 64.8 billion barrel recovery estimate from the 1970's does not seem realistic at this point in time. Maybe I am confused here, but in figure 9 of Khebab's original post it looks like the average estimate for cumulative recovery to date is roughly 60 billion barrels and based on figure 8 Ghawar's current production is still roughly 5 million BOPD (or 1.8 GB per year), so unless the field entirely stops producing in the next few years it is easily going to pass the 64.8 GB ultimate reserve level. This does not mean it will not go into steep decline in the near future, but there will certainly be a very long production life left for this field although at a much lower rate.
The Abqaiq reserves plot above is just for Arab-D, so that wouldn't be the case.
From this plot, Abqaiq has produced some from other reservoirs and is predicted to provide a production bump in the future:
Both this and the previous plots came from Saleri's CERA Week presentation:
http://www.cera.com/aspx/cda/filedisplay/filedisplay.ashx?PK=29004
This chart is typical of reserve growth (i.e. better technology + better field knowledge/management), reserves have more than doubled since the 50s but have reached an asymptote since the 90s. If we believe the USGS model, Abqaiq reserves will grow forever simply because their empirical growth model has no asymptote. It shows also that reserve growth after 50 years is problematic unless the field has been mothballed or mismanaged for an extensive period of time.
But what goes into the original estimate?
By circling the thing with water injectors, they've effectively delineated the productive volume. Perhaps they obtained a better understanding of the contours of the Arab-D, but it's hard to believe they were that far off originally that would warrant a change. Perhaps they overestimated the residual oil and realized after watering out a few wells that more was extracted than predicted.
Most of the reserves increase predated extraction technology that would have made a difference, so it would seem to more likely to be reservoir geology issues as opposed to technology.
I can't figure out anyway to justify the numbers from this paper. Given the age of the field.
I can't find a history of production problems that could have been overcome later for example.
Abiaq seems to have a lot of above ground handling equipment not related to the field but piped in from elsewhere.
If you read the quotes I found about the field in the 1990's during the first Gulf War the indication was it still had producing wells but that that the production was not amazing.
Bingo :)
And the oil drum strikes again
http://www.theoildrum.com/story/2006/8/16/13213/1413
http://www.theoildrum.com/classic/2005/06/picture-of-depletion.html
Assuming I found the field in google maps. It looks like a lot of infrastructure is around but dunes seem to be covering a lot of the roads. I could be wrong.
Here is a map with the field
http://www.gregcroft.com/area1indexmap.ivnu
I think I'm in the right place here.
http://maps.google.com/maps?f=q&hl=en&geocode=&time=&date=&ttype=&q=Ghaw...
Probably. I posted an image with the field outline for Euan awhile back. Have a look:
http://europe.theoildrum.com/node/3100/252277
I am working on a post with a lot more satellite porn.
Looks similar can you post your google link for that image ?
I just noticed most of the roads where covered by dunes.