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93 comments on A Nice Counterexample

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alanisthename on October 1, 2005 - 3:53am

I don't doubt depletion but I have a problem with the usefulness of Hubbert linearization. Take an oilfield that produces 1 (mbd) for ever. In a spreadsheet put 1 to 100 in column A. That's cumulative production. In B1 put =1/A1 and expand down to B100. That's annual production over cumulative production. Now chart it.

What you get is an asymptote that always starts at 1 (first year production/cumulative) and approaches the x axis but never gets there.

The chart for the UK and many others looks more like the chart for a `perpetual' oil field than a straight line. There aren't enough data points to distinguish between them so either could be true.

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ChrisPhoenix on October 1, 2005 - 8:42am

In your example, you don't get a straight line. It only looks approximately straight because of the large scale caused by the first few points.

So what you've discovered is that not all curves produce a straight line at all. In fact this seems to strengthen, not weaken the theory slightly, since the curve you identified that doesn't produce a straight line is also impossible in real life.

Chris

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Stuart Staniford on October 1, 2005 - 7:51pm

So fit that to the production curve to the most mature regions we have data for (like the US or Romania). It will suck - they don't look like hyperbolae. In general, for all you guys that want to propose other kinds of model - great, more power to you. But no-one's going to pay much attention to you unless you can show your model actually does a good job for some reasonable class of production regions. The reason Hubbert's model is famous is precisely because it has that property.

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JD on October 1, 2005 - 8:42pm

But no-one's going to pay much attention to you unless you can show your model actually does a good job for some reasonable class of production regions. The reason Hubbert's model is famous is precisely because it has that property.

It obviously doesn't do a good job for the world as a whole -- as demonstrated by Colin Campbell's failed predictions.

The only value which the linearization method might have is its ability to predict peak oil. Now, IIRC, Deffeyes predicts peak oil for Thanksgiving Day 2005 based on the linearization method, so that's the reality check.

Also, the method isn't objective until you specify an objective algorithm for selecting the line, and apply it uniformly in all cases. Otherwise, it's just subjective voodoo.

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Stuart Staniford on October 1, 2005 - 9:11pm

Actually, Campbell wasn't using the linearization method I don't think - I believe he was sticking in an explicit URR and constraining his fit to that. I wouldn't do that since our knowledge of reserves sucks. Our knowledge of production is imperfect (the different authorities differ as to the production numbers- maybe the Joint Oil Data Initiative is going to help here), but it's better than reserves.

I agree with you that the predictions of the world peak are a good check. However, Deffeyes used a particular oil data series (and I don't actually know which one!), and it's only fair to do comparison to whatever series he was fitting too. Also, obviously there's significant noise, so it could well be off by a few years either way (as it was for the US). But I don't believe it's going to be decades off. We need to get to some error analysis here soon to tighten that up (but one thing at a time).

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