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23 comments on Ghawar Numerology: Drilling in Uthmaniyah

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ace on April 1, 2008 - 2:10am Permalink | Subthread | Comments top

Great work! Thanks!

Your discussion about advancing water floods and well placement made me think further about rising water cut in Aramco’s fields.

The chart below is from Hans Jud’s Dec 2006 report, based mainly on Saleri’s CSIS Feb 2004 reports.
http://www.aspo-portugal.net/Articles/SA-Oilprod_field-by-field_V2.pdf

The chart shows rising production from Uthmaniyah North from 1999 to 2003 which corresponds to your increase in well numbers during the same time period.

Ghawar Production to 2003 - click to enlarge

Saleri gave a Feb 2008 presentation that can be found in the SPE Cairo Section of this link
http://www.leadingreservoirs.com/pda.htm

Saleri discloses some information about Abqaiq which might help with water cut estimates. According to Saleri, this chart shows that Abqaiq was still producing oil at a rate of about 400-500 kbd in 2006.

Abqaiq Reserves and Production to 2006 - click to enlarge

The next chart is also from the same Feb 2008 presentation. The four green lines have been added by me. Eternally optimistic Saleri thinks that the recovery factor can reach 80% of oil in place. I don’t.

Assuming that each blue dot in the chart below represents one month there appears to be little production from Abqaiq at the end of 2006 as the blue dots are in a horizontal position at about 55% oil in place. The water/oil ratio at the end of 2006 was about 0.7 which is equivalent to a water cut of 41%.

Abqaiq Water/Oil Ratio vs % Oil in Place Produced to 2006 - click to enlarge

Saleri has fitted a black line to the blue dots indicating a reasonable rise in the water/oil ratio. However, according to this article, a new fitted line should be added after every workover as shown in the chart below.
http://www.ogj.com/articles/save_screen.cfm?ARTICLE_ID=192951

Consequently, I have added the three green lines, representing pre and post workover events, in the chart above in an attempt to forecast the water/oil ratio. These recent workover events correspond roughly to horizontal wells, MRC wells and smart wells. Note that the green lines intersect at a water/oil ratio of about 5 or water cut of 83%. If 83% is assumed as the point when the oil production wells have to abandoned then the recovery factor for Abqaiq is 65% which is about a URR of 13 Gb for Abqaiq.

Assuming that Abqaiq has produced 400 kbd from start of 2007 to end of first quarter 2008, this means that Abqaiq cumulative production is about 11.3 Gb now. So there's only about 1.7 Gb left. I'm estimating that Abqaiq is probably declining about 10%/year now.

Uthmaniyah North, Abqaiq and Ain Dar/Shedgum are close to each other and have been in production for many decades. It would not surprise me that the water cut of these three regions was approaching 45%.

Oil and Gas Journal – Technique forecasts production from waterflooded reservoirs - click to enlarge

What is remarkable is Saudi Arabia’s consistent export volumes of Saudi light and extra light crude to IEA member countries as shown below.

Saudi Exports to IEA member countries (measured at the importing terminal) - click to enlarge

There about 28 IEA member countries which do not include China or India.
http://www.iea.org/about/membercountries.asp

Abqaiq is a significant source of extra light crude and Uthmaniyah North a significant source of light crude. The chart above shows that the export trend for Saudi light & extra light has been about 2.7 mbd since 2004. However, the exports of Saudi medium and heavy crudes have been dropping.

If water cut continues to rise in North Ghawar as well as Abqaiq there could be a faster decline in production and also in exports of Saudi light and extra light. Khursaniyah is coming on stream later this year and is also a source of light crude. Consequently, Saudi light and extra light crude export decreases may be delayed to 2009.

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Fractional_Flow on April 1, 2008 - 10:40am Permalink | Subthread | Parent | Comments top

Ace-

Thanks for the new data.

It seems that the projected Ultimate recovery is 13.9 Billion barrels for Abqaiq from the first figure, but much much greater from the WOR extrapolation.

Given the step in projected URR in 2006 from the first figure, it does not appear that there is much difference between your 13 Bbbl forecast and what is shown there... does there???

FF

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jimb on April 1, 2008 - 11:03am Permalink | Subthread | Parent | Comments top

JB: Thank you very much for your work. In my opinion you need to understand the development history of a field in order to better understand the reservoir and make reserve/production forecast, and this work makes understanding the development easy.

Ace: Thank you also. From what I have seen the data and analysis that you bring has always been tremendously helpful and informative. The first time I ever stumbled across TOD last year, just happened to be a day when you had posted a write up on world total liquids and C&C production rate and forecasts. I guess it was just coincidence (as many days it is just doom and gloom), but that definitely sold me on this site and I have always read it since then.

The data you added here on Ghawar really adds to this discussion and in general I agree completely with you. Especially on the main question as to when decline will start and what will the rate be. Two minor points that I would interpret slightly differently are on the fit of the WOR vs. recovery curve and the WOR at abandonment. Reserve forecasting and curve fitting are obviously subjective, but just looking at the curve I would probably forecast a line somewhere between your green lines and Saleri's black line. His does look ridiculously optimistic, but I think yours look a little pessimistic also. I also think an abandonment water cut of 83% is too low. Ghawar is on land, the infrastructure is already in place, and it is the biggest field in the world. In my opinion they will probably be producing this field well above a water cut of 99%. This does not change the fact that the field has produced the bulk of its reserves and decline is imminent if not already started, but I think it will ultimately make more than the 1.7 GB although it will be over a very long time frame.

Thanks again for all your work. I have learned a great deal from reading your posts.

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memmel on April 1, 2008 - 11:08am Permalink | Subthread | Parent | Comments top

Ace fantastic followup you comment should be merged with the main article.

A big point is we are seeing a field that close to 85% depleted yet production levels remain high.
This follows what I've seen from looking at a number of fields that we can maintain production rates up to about 90% depletion for individual fields before it drops off a cliff.

This is consistent with my assertion that the world is actually at a much higher depletion level then most people realize somewhere between 70-90% depleted not the 50% that a symmetric production profile would produce.

The only thing I thing your wrong about is the decline rate for the field 10% is too low try 15-30% post peak production decline rates and assume that production will remain flat for longer.

So I think your wrong about it being in decline now I think decline will set in a bit later towards the end of 2008 but will be a lot steeper. Of course the exact date is impossible to determine but by the end of the year the field should be both in decline and declining at a rate higher than your 10% estimate.

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Neven911 on April 1, 2008 - 10:51pm Permalink | Subthread | Parent | Comments top

Memmel,

Do you have any case studies of this asymmetric peak? this field has been in production some 60+ years and without decline will max out in another 11, so the evidence would point to a faster decline (or oil is abiotic) or they grossly underestimated the reserve.

Ace,

Is there a case reapplying Hubbert peaks after a rework? ie after you alter the methodology for extracting the oil are you starting from scratch with an albeit smaller reservoir?

Also does anyone know how to pronounce Ghawar?

Neven

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memmel on April 2, 2008 - 2:45am Permalink | Subthread | Parent | Comments top

WebHubbleTelescope has acutually run the math through his shock model. We disagree on the actual amount of backdated reserves and I've not seen his results for actual data.

http://mobjectivist.blogspot.com/2005/11/can-we-delay-peak-by-upping-ext...

Ivanhoe has almost exactly the numbers I've come up with.

http://hubbert.mines.edu/

Paper here
http://hubbert.mines.edu/news/Ivanhoe_96-1.pdf

GailTheActuary posted a key post showing that stated reserves and production where not consistent.
I don't have the link but its recent. I believe the Ivanhoe link was posted on that thread.

http://www.theoildrum.com/node/3664

Here is one of my original posts starting with water cut.

http://www.theoildrum.com/node/3272#comment-267260

Given that most of the world oil discoveries are in the past when Ivanhoe made his prediction 1992.
And given the world water cut from the Ferro paper of 80-90%.

And given Gails work then if your willing to discount the large reserve additions not backed by new discoveries then I'm probably right are actually Ivanhoe is I just came to the same conclusion via a different route.

Other approaches show asymmetric production.

Bakhtiari's WOCAP model is not all that different and has been the most accurate to date.
http://www.sfu.ca/~asamsamb/sb.htm

I'm not finding one of the graphs with a lot of models on it its common you can google for it.
But most have asymmetric production curves. HL is symetric only because if the simplicity of the model.
Both its power and weakness.

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23 comments on Ghawar Numerology: Drilling in Uthmaniyah

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