- The debate over oil's origin has been going on since
the 19th century. From the start, there were those who contended that oil
is primordial - that it dates back to Earth's origin - or that it is made
through an inorganic process, while others argued that it was produced
from the decay of living organisms (primarily oceanic plankton) that
proliferated millions of years ago during relatively brief periods of
global warming and were buried under ocean sediment in fortuitous
circumstances.
-
- During the latter half of the 20th century, with
advances in geophysics and geochemistry, the vast majority of scientists
lined up on the side of the biotic theory. A small group of mostly Russian
scientists - but including a tiny handful Western scientists, among them
the late Cornell University physicist Thomas Gold - have held out for an
abiotic (also called abiogenic or inorganic) theory. While some of the
Russians appear to regard Gold as a plagiarist of their ideas, the
latter's book The Deep Hot Biosphere (1998) stirred considerable
controversy among the public on the questions of where oil comes from and
how much of it there is. Gold argued that hydrocarbons existed at the time
of the solar system's formation, and are known to be abundant on other
planets (Jupiter, Saturn, Uranus, and some of their moons) where no life
is presumed to have flourished in the past.
-
- The abiotic theory holds that there must therefore be
nearly limitless pools of liquid primordial hydrocarbons at great depths
on Earth, pools that slowly replenish the reservoirs that conventional oil
drillers tap.
-
- Meanwhile, however, the oil companies have used the
biotic theory as the practical basis for their successful exploration
efforts over the past few decades. If there are in fact vast untapped deep
pools of hydrocarbons refilling the reservoirs that oil producers drill
into, it appears to make little difference to actual production, as tens
of thousands of oil and gas fields around the world are observed to
deplete, and refilling (which is indeed very rarely observed) is not
occurring at a commercially significant scale or rate except in one minor
and controversial instance discussed below.
-
- The abiotic theorists also hold that conventional
drillers, constrained by an incorrect theory, ignore many sites where
deep, primordial pools of oil accumulate; if only they would drill in the
right places, they would discover much more oil than they are finding now.
However, the tests of this claim are so far inconclusive: the
best-documented "abiotic" test well was a commercial failure.
-
- Thus even if the abiotic theory does eventually prove
to be partially or wholly scientifically valid (and that is a rather big
"if"), it might have little or no practical consequence in terms of oil
depletion and the imminent global oil production peak.
-
- That is the situation in a nutshell, as I understand
it, and it is probably as much information as most readers will need or
want on this subject. However, as this summary contradicts some of the
more ambitious claims of the abiotic theorists, it may be helpful to
present in more detail some of the evidence and arguments on both sides of
the debate.
-
- Oil at the Core?
-
- Gold is right: there are hydrocarbons on other
planets, even in deep space. Why shouldn't we expect to find primordial
hydrocarbons on Earth?
-
- This is a question whose answer is only partly
understood, and it is a complicated one. The planets known to have
primordial hydrocarbons (mostly in the form of methane, the simplest
hydrocarbon) lie in the further reaches of the solar system; there is
little evidence of primordial hydrocarbons on the rocky inner planets
(Mercury, Venus, Earth, and Mars). On the latter, possibly the
hydrocarbons either volatized and escaped into space early in the history
of the solar system, or - as Gold theorizes - they migrated to the inner
depths. (Note: very recent evidence of methane in the atmosphere of Mars
is being viewed as evidence of biological activity, probably in the
distant past. (1)) There is indeed evidence for deep methane on Earth: it
vents from the mid-oceanic ridges, presumably arising from the mantle,
though the amount vented is relatively small - less than the amount
emitted annually in cow farts (incidentally, there are persuasive biotic
explanations for the origin of this vented methane).
-
- A new study by the US Department of Energy and
Lawrence Livermore Lab suggests that there may be huge methane deposits in
Earth's mantle, 60 to 120 miles deep. (2) But today oil companies are
capable of drilling only as deep as six miles, and this in sedimentary
rock; in igneous and metamorphic rock, drill bits have so far penetrated
only two miles. (3) In any attempt to drill to a depth remotely
approaching the mantle, well casings would be thoroughly crushed and
melted by the pressures and temperatures encountered along the way.
Moreover, the DOE study attributes the methane deposits it hypothesizes to
an origin different from the one Gold described.
-
- More to the point, Gold also claimed the existence of
liquid hydrocarbons - oil - at great depths. But there is a problem with
this: the temperatures at depths below about 15,000 feet are high enough
(above 275 degrees F) to break hydrocarbon bonds. What remains after these
molecular bonds are severed is methane, whose molecule contains only a
single carbon atom. For petroleum geologists this is not just a matter of
theory, but of repeated and sometimes costly experience: they speak of an
oil "window" that exists from roughly 7,500 feet to 15,000 feet, within
which temperatures are appropriate for oil formation; look far outside the
window, and you will most likely come up with a dry hole or, at best,
natural gas only. The rare exceptions serve to prove the rule: they are
invariably associated with strata that are rapidly (in geological terms)
migrating upward or downward. (4)
-
- The conventional theory of petroleum formation
connects oil with the process of sedimentation. And, indeed, nearly all of
the oil that has been discovered over the past century-and-a-half is
associated with sedimentary rocks. On the other hand, it isn't difficult
to find rocks that once existed at great depths where, according the
theories of Gold and the Russians, conditions should have been perfect for
abiotic oil formation or the accumulation of primordial petroleum - but
such rocks typically contain no traces of hydrocarbons. In the very rare
instances where small amounts of hydrocarbons are seen in igneous or
metamorphic rocks, the latter are invariably found near
hydrocarbon-bearing sedimentary rocks, and the hydrocarbons in both types
of rock contain identical biomarkers (more on that subject below); the
simplest explanation in those cases is that the hydrocarbons migrated from
the sedimentary rocks to the igneous-metamorphic rocks.
-
- Years ago Thomas Gold recognized that the best test of
the abiotic theory would be to drill into the crystalline basement rock
underlying later sedimentary accumulations to see if there is indeed oil
there. He persuaded the government of Sweden in 1988 to drill 4.5 miles
down into granite that had been fractured by a meteorite strike (the
fracturing is what permitted drillers to go so deep). The borehole, which
cost millions to drill, yielded 80 barrels of oil. Even though the project
(briefly re-started in 1991) was a commercial failure, Gold maintained
that his ideas had been vindicated. Most geologists remained sceptical,
however, suggesting that the recovered oil likely came from drilling mud.
-
- The Russians (I must remind the reader that I am
actually talking about a minority even with the community of Russian
geologists) claim successes in drilling in basement rock in the
Dneiper-Donets Basin in the Ukraine. Professor Vladilen A. Krayushkin,
Chairman of the Department of Petroleum Exploration, Institute of
Geological Sciences, Ukrainian Academy of Sciences, Kiev, and leader of
the exploration project, wrote:
-
- The eleven major and one giant oil and gas fields here
described have been discovered in a region which had, forty years ago,
been condemned as possessing no potential for petroleum production. The
exploration for these fields was conducted entirely according to the
perspective of the modern Russian-Ukrainian theory of abyssal, abiotic
petroleum origins. The drilling which resulted in these discoveries was
extended purposely deep into the crystalline basement rock, and it is in
that basement where the greatest part of the reserves exist. These
reserves amount to at least 8,200 M metric tons [65 billion barrels] of
recoverable oil and 100 B cubic meters of recoverable gas, and are thereby
comparable to those of the North Slope of Alaska. (5)
-
- However, independent assessments of the situation do
not support these claims. First, the US Geological Survey does not agree
that the Dneiper-Donets reserves are that large (it cites 2.7 billion
barrels for total oil endowment). Second, the appearance of oil in
basement rocks is unusual but not unheard of, and there are various ways
in which oil can appear in basement rock. In the process of drilling
through overlying sedimentary rock, oil can be expelled downward so that
it appears to come from below. Then there are situations where igneous or
metamorphic rocks have migrated upward, or sedimentary rocks have migrated
downward, so that basement rock covers sedimentary rock (in some cases,
the overthrust may be hundreds of square kilometers in extent). In his
paper "Oil Production from Basement Reservoirs-Examples from USA and
Venezuela," Tako Koning of Texaco Angola, Inc., cites source rocks such as
marine shales in nearly all instances. (6) More to the point, numerous
studies cite the existence of sedimentary source rocks in the
Dneiper-Donets region. (7)
-
- Refilling Fields?
-
- Abiotic theorists often point out evidence of fields
refilling. The most-cited example is Eugene Island, the tip of a mostly
submerged mountain that lies approximately 80 miles off of the coast of
Louisiana. Here is the story as related by Chris Bennett in his article
"Sustainable Oil?" on WorldNetDaily.com:
-
- A significant reservoir of crude oil was discovered
nearby in the late '60s, and by 1970, a platform named Eugene 330 was
busily producing about 15,000 barrels a day of high-quality crude oil. By
the late '80s, the platform's production had slipped to less than 4,000
barrels per day, and was considered pumped out. Done. Suddenly, in 1990,
production soared back to 15,000 barrels a day, and the reserves which had
been estimated at 60 million barrels in the '70s, were recalculated at 400
million barrels. Interestingly, the measured geological age of the new oil
was quantifiably different than the oil pumped in the '70s. Analysis of
seismic recordings revealed the presence of a "deep fault" at the base of
the Eugene Island reservoir which was gushing up a river of oil from some
deeper and previously unknown source. (8)
-
- A "river of oil" from an unassociated deep source?
This does sound promising. But closer examination yields more prosaic
descriptions and explanations.
-
- According to David S. Holland, et al., in Search and
Discovery, the reservoir is characterized by
-
- 1. Structural features dominated by growth faults,
salt domes, and salt-related faulting.
-
- 2. Thick accumulations of predominantly deltaic
deposits of alternating sand and shale.
-
- 3. Young reservoirs (less than 2.5 m.y. old) with
migrated hydrocarbons whose origins are in deeper, organic-rich marine
shales.
-
- 4. Rapidly changing stratigraphy, due to deposition
and subsequent reworking.
-
- 5. Numerous oil and gas fields with stacked
reservoirs, long hydrocarbon columns, and high producing rates. (9)
-
- While it is true that the estimated oil reserves of
Eugene have increased, the numbers are not extraordinary. The authors note
that "From 1978 to 1988, these operations, activities, and natural factors
[including better exploration and recovery technology] have increased
ultimate recoverable reserves from 225 million bbl to 307 million bbl of
hydrocarbon liquids and from 950 bcf to 1.65 tcf of gas." Other estimates
now put the estimate of total recoverable oil as high as 400 Mb.
-
- None of this is especially unusual for a North
American oil field: most fields report reserve growth over time as a
consequence of Securities and Exchange Commission reporting rules that
require reserves to be booked yearly according to what portion of the
resource is actually able to be extracted with current equipment in place.
As more wells are drilled into the same reservoir, the reserves "grow."
Then, as they are pumped out, reserves decline and production rates
dwindle. No magic there.
-
- Production from Eugene Island had achieved 20,000
barrels per day by 1989; by 1992 it had slipped to 15,000 b/d, but
recovered to reach a peak of 30,000 b/d in 1996. Production from the
reservoir has dropped steadily since then.
-
- The evidence at Eugene Island suggests the existence
of deep source rocks from which the reservoir is indeed very slowly
refilling - but geologists working there do not hypothesize a primordial
origin for the oil. In "Oil and Gas - 'Renewable Resources'?" Kathy
Blanchard of PNL writes, "Recent geochemical research at Woods Hole
Oceanographic Institution has demonstrated that the wide range in
composition of the oils in different reservoirs of the Eugene Island 330
field can be related to one another and to a deeper source rock of
Jurassic-Early Cretaceous age." (10) Her article explains that this kind
of migration from nearby source rocks is hardly unique, and discusses it
in the context of conventional biotic theory. A technical paper by David
S. Holland, et al., "Eugene Island Block 330 Field - U.S.A. Offshore
Louisiana," published by AAPG, notes that the Eugene Island oils show
-
- abundant evidence of long-distance vertical migration.
Based on a variety of biomarker and gasoline-range maturity indicators,
these oils are estimated to have been generated at depths of 4572 to 4877
m (15,000 to 16,000 ft) at vitrinite reflectance maturities of 0.08 to
1.0% and temperatures of 150 to 170C (300 to 340F). Their presence in
shallow, thermally immature reservoirs requires significant vertical
migration. This is illustrated on Figure 36, which represents a burial and
maturation history for the field at the time of petroleum migration, that
is, at the end of Trimosina "A" time approximately 500,000 years ago. A
plot of the present measured maturity values versus depth is superimposed
on the calculated maturity profile for Trimosina "A" time to illustrate
the close agreement between measured and predicted maturity profiles. The
clear discrepancy between reservoir maturity and oil maturity is striking
and suggests that the oil migrated more than 3650 m (12,000 ft) from a
deep, possibly upper Miocene, source facies. Petroleum migration along
faults is indicated based on the observed temperature and hydrocarbon
anomalies at the surface and the distribution of pay in the subsurface.
These results are consistent with those of Young et al. (1977), who
concluded that most Gulf of Mexico oils originated 2438 to 3350 m (8000 to
11,000 ft) deeper than their reservoirs, from source beds 5 to 9 million
years older than the reservoirs. (11)
-
- Biomarkers
-
- The claims for the abiotic theory often seem
overstated in other ways. J. F. Kenney of Gas Resources Corporations,
Houston, Texas, who is one of the very few Western geologists to argue for
the abiotic theory, writes, "competent physicists, chemists, chemical
engineers and men knowledgeable of thermodynamics have known that natural
petroleum does not evolve from biological materials since the last quarter
of the 19th century." (12) Reading this sentence, one might assume that
only a few isolated troglodyte pseudoscientists would still be living
under the outworn and discredited misconception that oil can be formed
from biological materials. However, in fact universities and oil companies
are staffed with thousands of "competent physicists, chemists, chemical
engineers and men [and women!] knowledgeable of thermodynamics" who not
only subscribe to the biogenic theory, but use it every day as the basis
for successful oil exploration. And laboratory experiments have shown
repeatedly that petroleum is in fact produced from organic matter under
the conditions to which it is assumed to have been subjected over
geological time. The situation is actually the reverse of the one Kenny
implies: most geologists assume that the Russian abiotic oil hypothesis,
which dates to the era prior to the advent of modern plate tectonics
theory, is an anachronism. Tectonic movements are now known to be able to
radically reshuffle rock strata, leaving younger sedimentary oil- or
gas-bearing rock beneath basement rock, leading in some cases to the
appearance that oil has its source in Precambrian crystalline basement,
when this is not actually the case.
-
- Geologists trace the source of the carbon in
hydrocarbons through analysis of its isotopic balance. Natural carbon is
nearly all isotope 12, with 1.11 percent being isotope 13. Organic
material, however, usually contains less C-13, because photosynthesis in
plants preferentially selects C-12 over C-13. Oil and natural gas
typically show a C-12 to C-13 ratio similar to that of the biological
materials from which they are assumed to have originated. The C-12 to C-13
ratio is a generally observed property of petroleum and is predicted by
the biotic theory; it is not merely an occasional aberration. (13)
-
- In addition, oil typically contains biomarkers -
porphyrins, isoprenoids, pristane, phytane, cholestane, terpines, and
clorins - which are related to biochemicals such as chlorophyll and
hemoglobin. The chemical fingerprint of oil assumed to have been formed
from, for example, algae is different from that of oil formed from
plankton. Thus geochemists can (and routinely do) use biomarkers to trace
oil samples to specific source rocks.
-
- Abiotic theorists hypothesize that oil picks up its
chemical biomarkers through contamination from bacteria living deep in the
Earth's crust (Gold's "deep, hot biosphere") or from other buried
bio-remnants. However, the observed correspondences between biomarkers and
source materials are not haphazard, but instead systematic and predictable
on the basis of the biotic theory. For example, biomarkers in source rock
can be linked with the depositional environment; that is, source rocks
with biomarkers characteristic of land plants are found only in
terrestrial and shallow marine sediments, while petroleum biomarkers
associated with marine organisms are found only in marine sediments.
-
- The Bottom Line
-
- The points discussed above represent a mere sampling
of the issues; it would be difficult if not impossible for me to address
all of the arguments put forward by the abiotic theorists in a brief essay
of this nature. I circulated a draft of this essay on two energy-related
email newsgroups and received about a dozen thoughtful comments, one
defending the abiotic theory but most of the others critiquing it. About
half of the comments were from physicists, geophysicists, or geologists.
It quickly became apparent to me that a book-length treatment of the
subject is called for.
-
- J. F. Kenney has put forward a succinct and persuasive
paper arguing for the abiotic theory (5), but there is no prominently
published rebuttal piece that systematically discusses or attempts to
refute his assertions. A reader of Kenney's web site might find fault with
some of my statements in this essay (for example, as a counter to my
description of the depth "window" of oil formation, a reader might refer
to Kenneyís discussion of Russian experiments that have shown that oil can
be formed at high temperatures and high pressures - conditions similar to
those that must exist in the Earthís mantle). Yet among the draft comments
I received from scientists were convincing criticisms of Kenney's claims
(returning to my example: even if oil were formed in the mantle, as more
than one commenter pointed out, abiotic theorists have suggested no
plausible means by which it could rise to the depths at which we find it
without passing through intermediary regions in which the temperature
would be too high and pressure too low for liquid hydrocarbons to
survive). Many other assertions made by Kenney and critiqued by the
experts are more technical in nature and more difficult to summarize.
-
- So, rather than continuing along these lines, I would
prefer now to pull back from a focus on details and again emphasize the
bigger picture.
-
- There is no way to conclusively prove that no
petroleum is of abiotic origin. Science is an ongoing search for truth,
and theories are continually being altered or scrapped as new evidence
appears. However, the assertion that all oil is abiotic requires
extraordinary support, because it must overcome abundant evidence, already
cited, to tie specific oil accumulations to specific biological origins
through a chain of well-understood processes that have been demonstrated,
in principle, under laboratory conditions.
-
- Now, I like scientific mavericks; I tend to cheer for
the underdog. Peak oil is itself a maverick idea, and for the past several
years I have been promoting a view that the Wall Street Journal recently
described as "crackpot." (14) So I feel a bit unaccustomed and even
uncomfortable now to be on the side of the scientific "establishment" in
arguing against the abiotic oil theorists. The latter certainly deserve
their day in the court of scientific debate.
-
- Perhaps one day there will be general agreement that
at least some oil is indeed abiotic. Maybe there are indeed deep methane
belts twenty miles below the Earthís surface. But the important question
to keep in mind is: What are the practical consequences of this discussion
now for the problem of global oil depletion?
-
- I have not personally inspected the oil wells in Saudi
Arabia or even those in Texas. But nearly every credible report that I
have seen - whether from the industry or from an independent scientist -
describes essentially the same reality: discoveries are declining, and
have been since the 1960s. Spare production capacity is practically gone.
And the old, super-giant oil fields that the world depends upon for the
majority of its production are nearing or past their all-time production
peaks. Not even the Russian fields cited by the abiotic theorists as
evidence for their views are immune: in June the head of Russia's Federal
Energy Agency said that production for 2005 is likely to remain flat or
even drop, while other officials in that country have said that growth in
Russian production cannot be sustained for more than another few years.
(15)
-
- What if oil were in fact virtually inexhaustibleó?
Would this be good news? Not in my view. It is my opinion that the
discovery of oil was the greatest tragedy (in terms of its long-term
consequences) in human history. Finding a limitless supply of oil might
forestall nasty price increases and catastrophic withdrawal symptoms, but
it would only exacerbate all of the other problems that flow from oil
dependency - our use of it to accelerate the extraction of all other
resources, the venting of CO2 into the atmosphere, and related problems
such as loss of biodiversity. Oil depletion is bad news, but it is no
worse than that of oil abundance.
-
- Given the ongoing run-up in global petroleum prices,
the notion of peak oil hardly needs defending these days. We are seeing
the phenomenon unfold before our eyes as one nation after another moves
from the column of "oil exporters" to that of "oil importers" (Great
Britain made the leap this year). At some point in the very near future
the remaining nations in column A will simply be unable to supply all of
the nations in column B.
-
- In short, the global energy crisis is coming upon us
very quickly, so that more time spent debating highly speculative theories
can only distract us from exploring, and applying ourselves to, the
practical strategies that might preserve more of nature, culture, and
human life under the conditions that are rapidly developing.
-
- Footnotes
-
- 1. See New Scientist www.newscientist.com/news/news.jsp?id=ns99996425
-
- 2. www.eurekalert.org/pub_releases/2004-09/dlnl-mid091304.php
-
- 3. http://wow.osu.edu/Geology/ebmf.htm
-
- 4. See Kenneth Deffeyes, Hubbertís Peak, pp. 21-22,
171; Walter Youngquist, Geodestinies, p. 114.
-
- 5. www.gasresources.net/energy_resources.htm
-
- 6. www.dur.ac.uk/react.res/RRG_web/hydrocarbons_meet.htm
-
- 7. www.911-strike.com/pfeiffer.htm (link expired;
click on "cached")
-
- 8. www.wnd.com/news/article.asp?ARTICLE_ID=38645
-
- 9. #20003, 1999, www.searchanddiscovery.com/documents/97015/eugene.htm
-
- 10. www.pnl.gov/er_news/08_95/er_news/oil1.kb.html
-
- 11. www.datapages.com/97015/eugene.htm
-
- 12. See footnote 9.
-
- 13. www.giss.nasa.gov/gpol/abstracts/1997/FungFieldB.html
-
- 14. "As Prices Soar, Doomsayers Provoke Debate on
Oil's Future," 9/21/2004
-
- 15. www.mosnews.com/money/2004/06/17/oilproduction.shtml
-
- - Richard Heinberg is the author of Powerdown: Options
and Actions for a Post-Carbon World and The Party's Over: Oil, War and the
Fate of Industrial Societies; he is a Core Faculty member of New College
of California in Santa Rosa. www.museletter.com
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