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The Oil Drilling/Extraction Tech Thread (merged)

Discussions of conventional and alternative energy production technologies.

Unread postby JohnDenver » Thu 11 Nov 2004, 20:21:26

$this->bbcode_second_pass_quote('markcmyers', 'Y')ou guys are doing a great job explaining why production inevitably declines
at some point. But nothing you've said is a convincing argument why the decline must follow Hubbert's Curve.


There is no need for decline to follow Hubbert's Curve. Consider, for example, this graph of Russian production:

http://www.asponews.org/ASPO.newsletter.031.php#212

It has two humps, and the point where half the oil has been produced lies between them.

If you look at actual historical graphs of production, you will find many misshapen ones where the halfway point and peak do not coincide.
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Unread postby markcmyers » Thu 11 Nov 2004, 20:30:50

$this->bbcode_second_pass_quote('', 'T')here is no need for decline to follow Hubbert's Curve.


Now we're getting somewhere. If there's no need for decline to follow Hubbert's Curve, then the Curve may not be useful for predicting near-term oil shortages. Is that a reasonable conclusion?
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Unread postby JohnDenver » Thu 11 Nov 2004, 20:48:40

$this->bbcode_second_pass_quote('markcmyers', 'I')s it possible that no one fully understands the mechanism that underlies Hubbert's curve?


Yes, that is very possible. This is a very interesting line of inquiry you are pursuing. You'd think that ASPO would have carefully looked into it, but apparently they're too busy carping about the republicans and the dollar.
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Unread postby JohnDenver » Thu 11 Nov 2004, 21:09:15

$this->bbcode_second_pass_quote('markcmyers', 'N')ow we're getting somewhere. If there's no need for decline to follow Hubbert's Curve, then the Curve may not be useful for predicting near-term oil shortages. Is that a reasonable conclusion?


The predictive power of Hubbert's Curve is a myth. The myth says that Hubbert used some kind of mathematical curve to predict the US48 peak in 1970. In fact, Hubbert never produced any mathematical procedure/formula to justify his prediction. He just eyeballed it, took a guess and happened to be right. He also happened to be wrong about the world peaking in 1995, as Campbell has been wrong 2 or 3 times already.

The problem is that, in order to fit the curve, you must know the total area under the curve (i.e. total production, including the past and future). Unfortunately, nobody knows that number, and there is no scientific way to determine it. So people like Hubbert and Campbell make a guess. That's the bottom line of these predictions. It's like guessing how many beans are in a jar, when the size of the jar is partly hidden by a curtain. It's magic! :-D
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Unread postby markcmyers » Thu 11 Nov 2004, 22:05:16

Very useful, JohnDenver. Thank you.

I've been studying Peak Oil for only a short time, so I haven't had a chance to check much data. As I understand it, though, the Peak Oil people argue that Hubbert's Curve fits not only the US48, but other producing countries where the supply is in decline. There is, of course, more than a little circularity here, since the Peak Oil people use the model itself to determine how much oil is left.

Clearly, the model is far easier to disprove than prove. As you say, you need to know total reserves in order to prove the model, which is impossible without the model. But to disprove the model, all you need is an uncooperative curve segment, as in your Russian example.

So, JohnDenver, what is it that you do believe about the oil supply?
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Unread postby big_rc » Fri 12 Nov 2004, 00:12:44

$this->bbcode_second_pass_quote('JohnDenver', '
')
The predictive power of Hubbert's Curve is a myth. The myth says that Hubbert used some kind of mathematical curve to predict the US48 peak in 1970. In fact, Hubbert never produced any mathematical procedure/formula to justify his prediction. He just eyeballed it, took a guess and happened to be right.

The problem is that, in order to fit the curve, you must know the total area under the curve (i.e. total production, including the past and future).

It's magic! :-D


That is not exactly true. Hubbert's curve is a bell curve that is common in many systems. To say he "just eyeballed it" and got lucky is very disingenious, JD and also unfair to Hubbert and his work.

You don't have to know the total area under the curve. You only have to know a specified amount of the area and then you will be able to assess the Peak with some degree of accuracy. It's not "magic" but it is also not as precise as I think you want it to be. You keep harping on Campbell, Simmons, et al being wrong about assessing the actual peak but you keep forgetting that they are working with imprecise data. Do you also factor in hydrocarbon sources from "other" sources that are helping to boost production? What exactly is your margin of error for the Peak?

I think you keep forgetting what a massive, disperse global oil production system exists currently and that demand is affected by an infinite amount of variables. Honestly I'm impressed with many of their (Simmons, et al.) efforts and should be studied (not belittled). If you have ever done any modeling, you would appreciate how hard it is.
Simon's Law: Everything put together falls apart sooner or later.

I don't think of all the misery, but of all the beauty that still remains.--Anne Frank
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Unread postby big_rc » Fri 12 Nov 2004, 00:27:54

$this->bbcode_second_pass_quote('markcmyers', 'V')ery useful, JohnDenver. Thank you.

I've been studying Peak Oil for only a short time, so I haven't had a chance to check much data. As I understand it, though, the Peak Oil people argue that Hubbert's Curve fits not only the US48, but other producing countries where the supply is in decline. There is, of course, more than a little circularity here, since the Peak Oil people use the model itself to determine how much oil is left.

Clearly, the model is far easier to disprove than prove. As you say, you need to know total reserves in order to prove the model, which is impossible without the model. But to disprove the model, all you need is an uncooperative curve segment, as in your Russian example.

So, JohnDenver, what is it that you do believe about the oil supply?


Be careful with your argument. Since curves don't appear to follow a Hubbert-like bell curve, you should not totally dismiss Hubbert's theory out of hand. Production curves have been and are being manipulated by secondary and tertiary methods. This can result in a disfigured curve.

Additionally, Peak Oil people do not use the model to determine how much oil is left. People like Simmons and Hubbert use stated reserve numbers. Now the problem is which reserve numbers do you use? Once you get deeper into Peak Oil, you will see that this is the million dollar question and the heart of the problem. Also don't forget that everyone (and I mean every reputable body concerned with oil) agrees that we will peak. The only question is WHEN.
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Unread postby tdrive » Fri 12 Nov 2004, 00:56:42

$this->bbcode_second_pass_quote('', 'B')ut nothing you've said is a convincing argument why the decline must follow Hubbert's Curve. Do you see this?


The late K. Hubbert used a logistic curve. This, when referred to an oil reservoar depletion, later colloquially became "Hubbert Curve". In fact, this is a differential equation with an exponential solution. When declining, the oil extracted follows an exponential decline. The reason is, the secondary and tertiary extraction uses (in most cases) water, so the water "washes" the oil out and is later separated and injected again. The ratio of water/oil is called "water cut". 30% cut means for each 100 barrels of liquid extracted 30 are water, 70 are oil. The "washing" follows an exponential decline, kind of pumping clear water in a basin of black water and extracting the resulting mixture. The resulting mixture slowly turns grayish (less oil), and eventually the water in the basin becomes almost clear, since all the black has been washed out. The blackness of the take-out water falls exponentially like the other side of a bell curve.

For more information, please read a (very) introductory text on:

http://mathworld.wolfram.com/LogisticEquation.html

Is this explicit enough?

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Unread postby Keith_McClary » Fri 12 Nov 2004, 02:55:38

$this->bbcode_second_pass_quote('markcmyers', 'Y')ou guys are doing a great job explaining why production inevitably declines
at some point. But nothing you've said is a convincing argument why the decline must follow Hubbert's Curve. Do you see this?

Oilfields are usually developed by drilling many wells over a period of years

But suppose all the wells were drilled at the same time. Production would shoot up immediately from zero to the peak value and then decline thereafter. This has no resemblance to the Hubbert curve.

So this proves Hubbert is wrong. :o

The point is that Hubbert was doing empirical studies of the production curves of actual oilfields.

Suppose there is a graph of population vs. body weight and you are told that it peaks at 168 lb. Without seeing the graph, what percentage of the population would you guess weigh more than 168 lb.? Would you bet on it being much more or less than 50%?
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Unread postby Ayoob » Fri 12 Nov 2004, 03:31:06

Oil production may or may not exactly mirror a bell curve. The curve could have two humps or three, or more depending on political, economic, social, or other types of circumstances.

That said, production will still probably start slowly, ramp up, peak, and eventually tail off. Not much debate on that point. Of course, global oil production will probably have a bumpy plateau of production before it tails off and begins to fall due to the dispersion of oil fields and production methods.
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Unread postby Carmiac » Fri 12 Nov 2004, 05:18:51

$this->bbcode_second_pass_quote('', 'B')ut suppose all the wells were drilled at the same time. Production would shoot up immediately from zero to the peak value and then decline thereafter. This has no resemblance to the Hubbert curve.

So this proves Hubbert is wrong. :o


Um... No. First, Hubbert was discussing the real world, not some place where we wait untill we have found all of the oil fields to drill the first well.

Second, Hubbert was discussing the total production of a large number of wells over a large area.

Lets look at what happened in US48 as an example. When the first field was discovered people started looking for more place to drill. This started slowly at first and then expanded as more people with more money, better understanding of geology and better technology. As fields were discovered wells were drilled and started producing. Eventually most of the fields were discovered so it began to become harder to discover new fields and the rate of discovery decreased. As the older wells started to deplete and there were fewer new wells because of less discovery US48 production peaked and started to decline.

All fields start at zero production, end at zero production and have some sort production curve in the middle. If you add up enough of these fields, with their production spread out over time due to date of discovery and development, total production starts to resemble a bell curve. It dosen't matter what the production curve of a single field is. The Hubbert curve is the product of the cumulative effects of many fields.
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Unread postby JohnDenver » Fri 12 Nov 2004, 07:46:53

$this->bbcode_second_pass_quote('big_rc', 'P')eople like Simmons and Hubbert use stated reserve numbers.


I don't think Simmons has made any predictions about the peak date. He's made a lot of pessimistic comments about Saudi reserves, but he has no idea what they actually are. Let's not forget, Simmons isn't a geologist or a petroleum engineer; he's a banker.
Also, I don't think anyone knows exactly how Hubbert produced his famous prediction of the 1970 peak for US48. Do you have a cite to back up your claim that Hubbert used reserve numbers?

$this->bbcode_second_pass_quote('', ' ')Now the problem is which reserve numbers do you use? Once you get deeper into Peak Oil, you will see that this is the million dollar question and the heart of the problem.


Yes, and no one knows the answer. They are all just guessing. So who do you believe? The optimists or the pessimists? It's just gambling. Let's not be naive and pretend that "science" favors one side or the other.
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Unread postby khebab » Fri 12 Nov 2004, 10:19:57

$this->bbcode_second_pass_quote('JohnDenver', ' ')The problem is that, in order to fit the curve, you must know the total area under the curve (i.e. total production, including the past and future). Unfortunately, nobody knows that number, and there is no scientific way to determine it. So people like Hubbert and Campbell make a guess. That's the bottom line of these predictions. It's like guessing how many beans are in a jar, when the size of the jar is partly hidden by a curtain. It's magic! :-D


So if I understand correctly the real unknown variable is the total oil production. But what about the type of curve (logistic, gamma, gaussian??), it seems to me that the order of the model which is used for the fitting is also an unkwnown variable and can change dramatically the type of decline (steep or soft) after PO.
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Unread postby markcmyers » Fri 12 Nov 2004, 13:33:17

To me, the most interesting question, as well as the most practical one, is: If we assume that a point is going to come when the gap between production and demand catalyzes the collapse of global systems, is there a way to predict when that point is going to come?

To be more concrete about it, I suppose most people would agree that somewhere between $200 and $300 a barrel, things start falling apart. So do we have enough data, and robust enough theory, to predict approximately when that is going to happen? If so, then we can get some idea whether we have enough time to adjust consumption and phase in alternative energy sources in order to save ourselves. Or, if not, the most prescient of us become survivalists. Isn't this mainly what the debate is all about?

Is so, then I don't think any of us can afford to be either tendentious or glib about the predictive power of Hubbert. It is of the greatest importance, both for the race and for each of us personally, and certainly for our children and grandchildren, to understand what the truth is, if it can be known at all. With that in mind...

$this->bbcode_second_pass_quote('', 'H')ubbert's curve is a bell curve that is common in many systems.


Yes, it's common in many systems, but we still need proof that it applies to this system. For example, here's a system that ends in declining yield that, nevertheless, doesn't follow a bell curve:

When I make chicken stock, I use a 1-cup measuring cup to dip it out of the pot and into plastic bags. For awhile, I'm able to scoop a full cup. But then, when the level of stock in the pot reaches a certain point, the volume in each scoop begins to decline, and continues to decline until I'm not getting much stock at all with each scoop, and then I tilt the pot and pour. This system, as I say, doesn't follow a bell curve.

What's obvious is that after peak, production winds up following
some downward curve, but it looks to me as if it's not at all easy to prove that the curve has to be bell-shaped. Put another way, it's not clear that when half of all reserves are gone, production has to decline immediately. If that's so, then it becomes harder if not impossible to predict when $200 oil will come.

$this->bbcode_second_pass_quote('', 'Y')ou keep harping on Campbell, Simmons, et al being wrong about assessing the actual peak but you keep forgetting that they are working with imprecise data. Do you also factor in hydrocarbon sources from "other" sources that are helping to boost production?


$this->bbcode_second_pass_quote('', 'P')roduction curves have been and are being manipulated by secondary and tertiary methods. This can result in a disfigured curve.


But isn't this the point? If the model doesn't factor in such things as other hydrocarbon sources and other methods, how predictive can it be?

$this->bbcode_second_pass_quote('', '.')..demand is affected by an infinite amount of variables...


Well, exactly. And if a model doesn't take these variables into account, why are we defending it?

$this->bbcode_second_pass_quote('', 'P')eak Oil people do not use the model to determine how much oil is left. People like Simmons and Hubbert use stated reserve numbers.

I'm sorry, but this isn't true. Peak Oil people use Hubbert's 40-year discovery-to-reserves correlation to argue that current proven reserves are just about all that's left. Without this assumption, it becomes impossible to say with any confidence that we are now near peak. Herein lies the tautology.

$this->bbcode_second_pass_quote('', 'd')on't forget that everyone (and I mean every reputable body concerned with oil) agrees that we will peak. The only question is WHEN.

You don't need to be a reputable body concerned with oil to know that this is true. You just have to be conscious. So I don't see what this has to do with the present discussion.

$this->bbcode_second_pass_quote('', 'T')he reason is, the secondary and tertiary extraction uses (in most cases) water, so the water "washes" the oil out and is later separated and injected again.

Once again, this tells us that there will be a downward curve. It doesn't prove that it will be Hubbert's Curve.

$this->bbcode_second_pass_quote('', 'B')ut suppose all the wells were drilled at the same time. Production would shoot up immediately from zero to the peak value and then decline thereafter. This has no resemblance to the Hubbert curve.

I suppose one answer would be that, as you drill more wells in a field, you lower efficiency from a pressure standpoint, so that you wind up getting less overall yield. Still, it seems to me that, in the short term, which is what we're talking about, more wells would postpone decline, which, as Keith_McClary says, would blow up the Hubbert model.

It seems to me that Carmiac is stating the Hubbert theory rather than defending it.

$this->bbcode_second_pass_quote('', 'S')o if I understand correctly the real unknown variable is the total oil production. But what about the type of curve (logistic, gamma, gaussian??), it seems to me that the order of the model which is used for the fitting is also an unkwnown variable and can change dramatically the type of decline (steep or soft) after PO.

In other words, the two unknowns are how much oil we have left, and what happens now that we have that unknown amount left. If that's true, how can we say with any certainty that production is about to decline? It seems to me that anyone on either side who says they know what's going to happen in the next 10, 20, or 30 years is speaking from faith rather than knowledge.
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Unread postby Phil » Fri 12 Nov 2004, 14:52:15

Given that so many countries are past peak, and assuming each country has yielded about as much oil as was anticipated, I think to accurately predict the time of decline in the remaining countries (and therefore synthesize a World model) we can use the pre-OPEC reserve estimates of those countries with some confidence. I believe that's what Campbell, et al., have done.

I don't think Hubbert's theory states that it has to follow a particular type of curve, just that it will.

It seems to be that predictive power of these models lies in the modelers' ability to use historical data- to see for example that most fields tend to go into decline when half of the resource is recovered- perhaps as a function of the physics involved. I guess that's what you're trying to understand.

But I'm really not qualified to theorize.
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Unread postby Phil » Fri 12 Nov 2004, 15:18:37

$this->bbcode_second_pass_quote('Phil', 't')o see for example that most fields tend to go into decline when half of the resource is recovered...


I should amend that to say 20% of the resource, instead of half, since only 40% of the resource is recovered from a typical field, if I'm not mistaken.

Also, you have to consider that most of the easy to reach, light sweet crude oil has been produced, leaving the heavier sour oil to be extracted- which has different flow properties and will follow a different production curve- in more difficult or politically unstable regions.
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Unread postby Keith_McClary » Fri 12 Nov 2004, 15:29:12

$this->bbcode_second_pass_quote('Carmiac', '')$this->bbcode_second_pass_quote('Keith_McClary', 'B')ut suppose all the wells were drilled at the same time. Production would shoot up immediately from zero to the peak value and then decline thereafter. This has no resemblance to the Hubbert curve.

So this proves Hubbert is wrong. :o


Um... No. First, Hubbert was discussing the real world, not some place where we wait untill we have found all of the oil fields to drill the first well.

As I said in my next sentence(after the :o ):
$this->bbcode_second_pass_quote('Keith_McClary', '
')The point is that Hubbert was doing empirical studies of the production curves of actual oilfields.
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Unread postby markcmyers » Fri 12 Nov 2004, 15:45:35

I know this question marks me as someone who knows very little about the oil business, but is it safe to assume that in any field with an adequate volume of oil, additional wells can be drilled to temporarily boost production? If so, do the additional wells reduce the total amount of oil that can ultimately be extracted? Or do they just speed up depletion, with the total unchanged?
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Unread postby Phil » Fri 12 Nov 2004, 16:34:26

Image

I searched google for "field production" and found this graph.

$this->bbcode_second_pass_quote('', 'T')he next largest producer (fig. 28, site 1) yielded 18 million bbl of oil and 52 million bbl of brine during 1943-83. During 1943-66, the ratio of brine to oil was relatively stable, as production was mostly from the field shown as site 1 in figure 28. Subsequent oil production at site 4 resulted in significantly greater amounts of brine, and in 1971 oil production leveled off while brine production continued to increase exponentially (fig. 29). Ultimately, oil production began to decline in 1977, and brine production continued to rise. The brine-to-oil ratio in 1983 was 6.4 to 1.0 compared with a 1 to 1 ratio in 1964.
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Unread postby saudijones » Fri 12 Nov 2004, 23:16:08

stinky farts
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