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76 comments on When Does Hubbert Linearization Work?

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JD on September 29, 2005 - 7:39am Permalink | Subthread | Comments top
I'm skeptical about the tails of these graphs. It's clear from reading Aramco material that their production strategy is not to maximize near-term production. Rather, their strategy is to consistently plateau at a sub-maximal constant level, as they have been doing for years, and plan to continue in the future (e.g. at 12mbd).

For a producer following this strategy, the graph will take the non-linear form y=1/x, and foul up the linear extrapolation.

Also, has there ever been a case where the line actually hit the x-axis?

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NC on September 29, 2005 - 11:40am Permalink | Subthread | Parent | Comments top
JD
I'm still getting my head around these graphs, but isn't the slope telling you how fast they are depleting their reserve?  Look at the Iran graph, very shallow slope compared to Norwegian.  Doesn't this mean that extraction rate becomes ever smaller with respect to cumulative removed if extraction rate is held constant?  Even a fixed rate of extraction for very long time will still have a negative slope estimating total reserve.  Only increasing extraction rate keeps the slope positive.

If extraction rate peaks than the slope gets steeper.  If I understand your post you say that SA is artificially holding production below their maximum rate.  They could increase extraction rate and shift the slope into positive territory or so flat intersection with the X axis is meaningless?  This is what the left side of all charts shows.  Extraction rate is increasing faster than cumulative.  

But I am skeptical that after decades of pumping SA can increase their rate enough to change the slope very much. This would imply that very few of their wells have peaked and many have the potential for increased rate of extraction.  By increasing rates everywhere they could push the intersection to the X axis a bit to the right.  But this short term effect could be corrected later by steeper declines in extraction rate than previously calculated during the push for maximum extraction rate.

Am I on the right track here or just completely lost mathmatically?

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Stuart Staniford on September 29, 2005 - 11:45am Permalink | Subthread | Parent | Comments top
Ah. That would explain why their existing production is depleting at 5% to 12% annually.
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WebHubbleTelescope on September 30, 2005 - 12:14am Permalink | Subthread | Parent | Comments top
JD apparently knows nothing about the mathematical concept of an asymptote.

Oh, I forgot, asymptotes are features of junk science.

Seriously, it's like asking why log-log graph paper does not have any zero intercepts.

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jhm on September 30, 2005 - 4:55am Permalink | Subthread | Parent | Comments top
Speaking of log graphs, I was thinking that, as the wild swings in the curve for low cummulative output are exagerated (the ratio is more sensetive to chages in production for low cummulatives), the opposite might be true further out on the graph (the curve may not be sensitive enough to be enlightening for large cummulative values).  Perhaps putting these data on log paper, or some other non-linear scale, might be more illustrative.
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76 comments on When Does Hubbert Linearization Work?

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