- 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 isnít 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 skeptical, 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 ReservoirsóExamples 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 inexhaustibleówould
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 runup 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
|
