The Oil Drum

88 comments on Four US Linearizations

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Twilight on January 6, 2006 - 9:06am

But the earlier models weren't really wrong, they just did not account for the additional North Slope oil - which of course they could not. So Hubbert only models the "natural" behavior of fields, or aggregations of wells/fields. But if something else happens to monkey with them, it breaks down. This could be geopolitical, natural disaster, new technologies, or new discoveries. So the accuracy when applied to world oil production will be dependant on having a handle on new oil discoveries and all those other factors. OTOH, when you aggregate things, I bet you'll mostly see the effects of the few really big fields, and the effects of exceptional situations will tend to average out. If we had the data, we could tell where things were tracking.

I bet on the whole Hubbert will be pretty true as long as we account for new fields coming on line, with my biggest concern being whether techniques used to extend the production volume have significantly changed the shape of the curve.

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SkyWick on January 6, 2006 - 11:05am

But we do have a good grasp of how much is left to be discovered. The discovery data is well ahead of production. If we tie the discovery data into production, this should be factorable in as a variance percentage.

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ericy on January 6, 2006 - 12:15pm

Actually to a degree the Hubbert model does try and account for oil that is yet to be discovered.

In Deffeyes 2005 book "Beyond Oil", he applies Hubbert linearization not only to the oil we have already used, but also to two others.

The second plot is the amount of oil we have used plus the known reserves (removing bogus reserves from OPEC nations).

The third plot is 'hits'. Essentially a measure of oilfield discoveries, and this is an attempt to measure the amount of oil in oilfields yet to be discovered.

You can then fit straight lines to all 3 of these, and he has such graphs in one of his books. In the summary, he has the parameters for the lines that he fit to the things. All 3 have a Qt of 2.013 trillion barrels.

The first curve (oil that we have consumed already) has a=5.9%, peak 2005, and percentage used is 49%.

The second curve (oil that we have consumed plus reserves) has a=7.2%, peak 1978, and percentage of total of 82%.

The third curve (hits - oilfields that we know about) has a=8.1%, peak in 1964, and percentage of total of 94%.

The third curve implies that only 6% of the total world oil is in oilfields that we don't know about yet.

I have to admit that I am still a little fuzzy on the concept of 'hits', and what it means.

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Everett on January 6, 2006 - 3:11pm

Twilight,
Hubbert works well for USA oil, but by your definition, it is not entirely "natural". For geopolitical factors, many areas were placed out-of-bounds for environmental reasons. There were many innovations integrated into the production data. Even with the major recent discovery, the North Slope, the older estimates project forward fairly well.

For USA oil, Hubbert seems to cope well with most of the "unnatural" factors that you mention. Going global, politics will probably throttle production more than disasters. New discoveries probably won't be as significant for the world as for the USA. It is likely that we will need some stupendous additional innovation just to match the innovation embedded in the USA models. This reasoning implies less global URR "loft" and global depletion rate "depression" than we see with the USA models.

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Twilight on January 6, 2006 - 4:21pm

Yes, I guess that's why I suspect that the Hubbert model will work, because even in this example, where we did indeed have all of those issues, it still works pretty well. That tells me that you'd really have to "monkey" with things a lot to get to the point where the errors are really big. I think it's just that the effects of the really big fields swamp out everything else - combining with smaller fields of similar shape just shifts the curve a bit. As goes Ghawar, so goes the world.