I like reading Steven Weber's posts at HuffPo : Oilfinger. Weber has a very dense, elliptical, and snarky style, which keeps me interested even though I can't always pin down his ultimate point.There are two contexts for the use of a Hubbert/Logistic curve:I responded to his comment:
1. logistic demographic modeling as initially proposed by Pierre François Verhulst.
2. curve fitting as Hubbert did.
WHT's arguments are dealing with the first context whereas you are putting yourself in the second context. The power of (1) is that you are trying to physically model the observed phenomenon using a differential equation. In the case of a logistic curve, the differential equation is modeling a birth-death process as explained by WHT
Khebab nailed it by placing it in the 2 contexts. As I said before, you cannot ascribe any physical meaning to the parameters if it is simply a curve-fitting exercise. And in the other context, we just can't make any sense of the model in terms of oil production.So now we have a logical proof that the Logistic model has absolutely nothing to do with "deaths" of oil wells or oil regions. I know this won't prevent TOD commenters from continuing to use improper analogies to "explain" what the Logistic (and HL) means but we have to draw a line in the sand.
Let me present another perplexing situation. If we actually consider the full birth-death model:
dP/dt = (B0-B1*P-D0-D1*P)*P = (B0-D0)*P - (B1+D1)*P2
you notice that in terms of birth and death, this gives us asymptotic P as the current carrying capacity. The equivalence between carrying capacity and URR makes absolutely no sense if we keep the death terms in the equation. Remember that deaths essentially knock out entities from the current population and the number of entities that have actually existed over all time would be infinite! But we know that URR << infinity.
What this means for the oil analogy is that we would have to present the Birth/Death model as purely a Birth model. In other words, births don't give rise to deaths but they do add to the cumulative growth. Otherwise, we would significantly undercount the URR as deaths would invisibly remove "entities" from the cumulative count.
So the next time someone talks about oil fields dying and trying to relate that to Logistic/HL modeling, point them here.
As Khebab said, no problem if you use HL as simply a curve fitting exercise, but you cannot ascribe any further meaning to it.
If we want to go with something simple, then go with something simple. For instance, why the heck don't we just plot the first derivative of yearly production with respect to time and then plot that? Around the peak, this will turn into a straight line with negative slope and you should be able to discern the peak by where it goes through zero (i.e. the slope flips sign around the peak).
This is based purely on calculus and the Taylor series approximation that every quasi-symmetrically peaked curve has major terms like A-B*(t-t0)2 around the peak. Take the derivative of that curve and you get 2B*(t0-t) which you and I and everyone else can easily understand as a negatively sloped straight line which crosses the axis at peak.
I know that this completely obscures the subject of URR, but URR is not even important here, based on the same assumption of a quasi-symmetric peak. As much of the production will appear on one side of the peak as the other for a more-or-less symmetric curve, so just ignore the URR.
So I see it that we have two routes to take:
1) Go for the trivial analysis as above (therefore undermining HL, which has proven to be a perfect example of a concocted and contrived analysis)
2) Go for a real model of oil discovery and depletion
I'm all for (2) but if we really want to do (1) then let's really agree to finding the faults with HL.
Never quite sure what it actually is, but it is a unique taste., August 24, 2006To answer the last question: it really did help me. Now I know how these empty-headed meat-sticks think. But with a level of intellect below dirt, somebody must give them marching orders to follow.
Reviewer: Craig Matteson
There is a reason that Slim Jim doesn't ever quite say what it is. It isn't a beef stick. It isn't jerky. It is what it is. I remember eating them when they first came out and wondering what they were. Now, tasting them again, I remember the question. There is some kind of meat in there, but it is treated in a lot of different ways. A Slim Jim is still as greasy as I remember, as well. The trick is to enjoy them without eating them to excess. For what they are, they are convenient, tasty, and can be fun.
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"It's true, it works," Dr. Roy said. "Everyone told me, 'Rustum, don't be fooled. He put electrodes in there.' "I remember happening across Roy's name many a time back in the day, and note here his prolific nature (almost 800 reviewed papers and patents).
But there are no electrodes and no gimmicks, he said.
RustumRoy.comRustum Roy cannot be described by any professional label. He has interwoven throughout his 60 year career both world-class science and active participation in reforming theology and the practice of religion. He is at once a distinguished research scientist and a social activist, a societal reformer and a champion of whole person healing (or CAM). He currently holds professorships at Penn State, Arizona State and the University of Arizona covering those fields.hey Rusty, pull your underwear inside-out, stick it on your head, and people will clearly see how the Fruit-of-the-Loom label sticks.
Anyway, he's not exactly a cancer researcher, he's a retired TV station engineer who discovered that retirement sucks - but that's been discovered before. He then decided to see if his RF generator would desalinate water, but when he tried the water caught on fire. He needed a scientist. Instead, he found Rustum Roy, an emeritus chemistry professor at Penn State, who called it "the most remarkable discovery in water science in 100 years." That would include "polywater," which Roy fell for 40 years ago. Roy said that RF weakens chemical bonds, releasing hydrogen which burns. It's the Bush "hydrogen initiative" fallacy again (WN 31 Jan 03) . Must I now lecture a chemistry professor on thermodynamics? More energy is needed to free hydrogen than you get by burning it. The story was shunned by major news outlets, except, of course, Fox News, which did point out that Rustum Roy is also "a specialist in holistic medicine and Christian sexuality."
The situation is likely to become even more dire in the near future. Kornbluth and Leslie Theiss, field office manager at the US Bureau of Land Management's helium operations in Amarillo, say the worldwide demand for helium is growing, fueled at least in part by the growth of high-tech manufacturing in China, Japan, Taiwan, and South Korea. Companies in those countries use helium in the production of semiconductors, flat-panel displays, and optical fibers.Bob Park said pretty much the same thing a few years ago. I would imagine that this peak and decline will play out in some quite unexpected ways. Professional clowns will feel the hurt first and the hardest.
Meanwhile, the tightened supply and higher costs are prompting efforts in both academia and industry to convert to dry cryostats, or closed-cycle refrigerant units, which eliminate the need to replenish helium. But the systems don't suit everyone. They're costly—up to $50 000 apiece, according to Allen Goldman, a physicist at the University of Minnesota. And some units' base temperatures are limited, able to bring helium down to only 2.7 K, not cold enough for all types of research.
Until other sources are developed, industry officials warn, the worldwide helium supply will continue to be squeezed. "We're producing everything we can here but it just isn't enough," says Theiss.