- Ugo Bardi is professor of Chemistry at the University
of Florence, Italy. He is also member of the ASPO (Association for the
study of peak oil). He is the author of the book "La Fine del
Petrolio"
(the end of oil) and of several studies on oil depletion.
-
- Ugo Bardi offers a simple assessment of the abiotic
theory.
His logic is so clear, and the culmination of his argument is so cogent,
that even a child could understand it. And the conclusion is inescapable
- at least to honest enquiry - abiotic theory is false, or at best
irrelevant.
-DAP
-
- (FTW) -- For the past century or so, the biological
origin
of oil seemed to be the accepted norm. However, there remained a small
group of critics who pushed the idea that, instead, oil is generated from
inorganic matter within the earth's mantle.
-
- The question might have remained within the limits of
a specialized debate among geologists, as it has been until not long ago.
However, the recent supply problems have pushed crude oil to the center
stage of international news. This interest has sparked a heated debate
on the concept of the "production peak" of crude oil. According
to the calculations of several experts, oil production may reach a maximum
within a few years and start a gradual decline afterwards.
-
- The concept of "oil peak" is strictly linked
to a view that sees oil as a finite resource. Several economists have never
accepted this view, arguing that resource availability is determined by
price and not by physical factors. Recently, others have been arguing a
more extreme view: that oil is not even physically limited. According to
some versions of the abiotic oil theory, oil is continuously created in
the Earth's mantle in such amounts that the very concept of
"depletion"
is to be abandoned and, by consequence, that there will never be an
"oil
peak."
-
- The debate has become highly politicized and has spilled
over from geology journals to the mainstream press and to the fora and
mailing lists on the internet. The proponents of the abiotic oil theory
are often very aggressive in their arguments. Some of them go so far as
to accuse those who claim that oil production is going to peak of pursuing
a hidden political agenda designed to provide Bush with a convenient excuse
for invading Iraq and the whole Middle East.
-
- Normally, the discussion of abiotic oil oscillates
between
the scientifically arcane and the politically nasty. Even supposing that
the political nastiness can be detected and removed, there remains the
problem that the average non-specialist in petroleum geology can't hope
to wade through the arcane scientific details of the theory (isotopic
ratios,
biomarkers, sedimentary layers and all that) without getting lost.
-
- Here, I will try to discuss the origin of oil without
going into these details. I will do this by taking a more general approach.
Supposing that the abiogenic theory is right, then what are the
consequences
for us and for the whole biosphere? If we find that the consequences do
not correspond to what we see, then we can safely drop the abiotic theory
without the need of worrying about having to take a course in advanced
geology. We may also find that the consequences are so small as to be
irrelevant;
in this case also we needn't worry about arcane geological details.
-
- In order to discuss this point, the first task is to
be clear about what we are discussing. There are, really, two versions
of the abiotic oil theory, the "weak" and the
"strong":
-
- - The "weak" abiotic oil theory: oil is
abiotically
formed, but at rates not higher than those that petroleum geologists assume
for oil formation according to the conventional theory. (This version has
little or no political consequences).
-
- - The "strong" abiotic theory: oil is formed
at a speed sufficient to replace the oil reservoirs as we deplete them,
that is, at a rate something like 10,000 times faster than known in
petroleum
geology. (This one has strong political implications).
-
- Both versions state that petroleum is formed from the
reaction of carbonates with iron oxide and water in the region called
"mantle,"
deep in the Earth. Furthermore, it is assumed (see Gold's 1993 paper) that
the mantle is such a huge reservoir that the amount of reactants consumed
in the reaction hasn't depleted it over a few billion years (this is not
unreasonable, since the mantle is indeed huge).
-
- Now, the main consequence of this mechanism is that it
promises a large amount of hydrocarbons that seep out to the surface from
the mantle. Eventually, these hydrocarbons would be metabolized by bacteria
and transformed into CO2. This would have an effect on the temperature
of the atmosphere, which is strongly affected by the amount of carbon
dioxide
(CO2) in it. The concentration of carbon dioxide in the atmosphere is
regulated
by at least two biological cycles; the photosynthetic cycle and the
silicate
weathering cycle. Both these cycles have a built-in negative feedback which
keeps (in the long run) the CO2 within concentrations such that the right
range of temperatures for living creatures is maintained (this is the Gaia
model).
-
- The abiotic oil-if it existed in large amounts-would
wreak havoc with these cycles. In the "weak" abiotic oil version,
it may just be that the amount of carbon that seeps out from the mantle
is small enough for the biological cycles to cope and still maintain
control
over the CO2 concentration. However, in the "strong" version,
this is unthinkable. Over billions of years of seepage in the amounts
considered,
we would be swimming in oil, drowned in oil.
-
- Indeed, it seems that the serious proponents of the
abiotic
theory all go for the "weak" version. Gold, for instance, never
says in his 1993 paper that oil wells are supposed to replenish
themselves.1
As a theory, the weak abiotic one still fails to explain a lot of
phenomena,
principally (and, I think, terminally): how is it that oil deposits are
almost always associated to anoxic periods of high biological sedimentation
rate? However, the theory is not completely unthinkable.
-
- At this point, we can arrive at a conclusion. What is
the relevance of the abiotic theory in practice? The answer is
"none."
The "strong" version is false, so it is irrelevant by definition.
The "weak" version, instead, would be irrelevant in practice,
even if it were true. It would change a number of chapters of geology
textbooks,
but it would have no effect on the impending oil peak.
-
- To be sure, Gold and others argue that even the weak
version has consequences on petroleum prospecting and extraction. Drilling
deeper and drilling in areas where people don't usually drill, Gold says,
you have a chance to find oil and gas. This is a very, very weak position
for two reasons.
-
- First, digging is more expensive the deeper you go, and
in practice it is nearly impossible to dig a commercial well deeper than
the depth to which wells are drilled nowadays, that is, more than 10
km.
-
- Secondly, petroleum geology is an empirical field which
has evolved largely by trial and error. Petroleum geologists have learned
the hard way where to drill (and where not to drill); in the process they
have developed a theoretical model that WORKS. It is somewhat difficult
to believe that generations of smart petroleum geologists missed huge
amounts
of oil. Gold tried to demonstrate just that, and all that he managed to
do was to recover 80 barrels of oil in total, oil that was later shown
to be most likely the result of contamination of the drilling mud. Nothing
prevents others from trying again, but so far the results are not
encouraging.
-
- So, the abiotic oil theory is irrelevant to the debate
about peak oil and it would not be worth discussing were it not for its
political aspects. If people start with the intention of demonstrating
that the concept of "peak oil" was created by a "Zionist
conspiracy" or something like that, anything goes.
-
- In this case, however, the debate is no longer a
scientific
one. Fortunately, as Colin Campbell said, "Oil is ultimately
controlled
by events in the geological past which are immune to politics."
-
- Thomas Gold, of Cornell University, has been one of the
leading proponents of the abiotic oil theory in the West. The theory,
actually,
had its origin in the work of a group of Ukrainian and Russian
scientists.
-
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