FYI: a brief review of deep drilling and abiotic oil theory was
recently published. Here's the section on abiotic oil, and the
concluding passages. The rest of the text, and references, are
at the link. ---Alan
........................................
http://drillinglab.mred.tuc.gr/Publications/56.pdf 3rd AMIREG International Conference (2009): Assessing the
Footprint of Resource Utilization and Hazardous Waste
Management, Athens, Greece
Challenges for very deep oil and gas drilling - will there
ever be a depth limit?
V.C. Kelessidis
Department of Mineral Resources Engineering, Technical
University of Crete, Hania, Greece
ABSTRACT
The continuous and ever increasing demand for fossil fuels and
in particular oil and gas has pushed drilling and exploration
industry to drill in ultra deep waters (water depths more than
2000 m) with the wells drilled to depths in excess of more
than 7500 m. These wells are very expensive to drill and
complete with costs up to about $100 million. Reservoir
challenges are pore pressures that exceed 138 MPa beyond the
limit of some current logging tools while the temperatures
are not as extreme being around 125 degC. In this paper we
examine the challenges placed on drilling equipment,
critically review the state of the art on developing new tools
and techniques to withstand these high pressures and present
views about the potential depth limits for hydrocarbon
drilling. In addition, techniques and innovative tools to
address these challenges are presented. The abiotic theory of
hydrocarbon generation from the depths of earth is also
reviewed, based on prior and recent research findings, and
the implications of such a theory are critically discussed.
Whatever the origin of hydrocarbons, the challenges will be in
the very deep boreholes and ultra deep water levels, requiring
innovations and excellent teams from top notch professionals.
1. INTRODUCTION
[...snip...]
6. THE ABIOTIC THEORY OF HYDROCARBON GENERATION
The general saying among oil well drillers is that oil is
where you find it, meaning that oil has been found in
traditional and non-traditional places. What of course is
considered traditional is that oil is found in sedimentary
rocks, very close to the surface in the beginning of the
century, while nowadays it may be found at considerable
depths, now reaching almost 9000 m from the surface. There are
of course finds in fractured basement rocks (metamorphic or
igneous rocks) from where they are produced (Sircar, 2004).
Batchelor and Gutmanis (2005) have compiled an extensive list
of fields producing hydrocarbons from basement rocks, although
most petroleum geologists dismiss them as being of
non-commercial value.
However, White Tiger, the oil field in Vietnam may prove them
wrong because it is an excellent example of production from
basement rock. The field currently produces 350.000 barrel
oil per day, expecting to produce overall 600 million barrels
(47 years of production at this pace). The granitic basement
rock is highly fissured (Fig. 8 ) with apparent permeabilities
ranging from a few mD to up to 464 mD (Chan et al., 2006). The
oil that is produced, however, has been characterized of
biogenic origin (Nemchenko et al., 2007) with migration from
underlying sedimentary rocks.
Of course, we find oil 'where it is', where it has remained
for ages, but how was it formed? Current belief is that oil is
of biotic origin, through accumulation of organic matter
(plankton, single cell organisms that floated on ocean
surface) and sedimentation followed by burial. For large
periods organic material has been under very high pressures
and temperatures, in the range of 130-150 degC, in a 'cooking
pot' and gradually transformed to petroleum. Because of its
lower density, it has migrated upwards and some surfaced and
was lost, while some has hit non-permeable layers (the seal)
and accumulated in the porous sedimentary rocks creating the
world's oil and gas fields.
There is, however, another school of thought, not very well
known until recent years, which is gaining, though, momentum.
It is the theory of abiotic (or abiogenic) origin of
petroleum, that hydrocarbons have been formed in the depths of
earth by reduction of CO2 and H2 gases in the presence of
metal catalysts (Gold and Soter, 1980; Kenney, 1994;
Krayushkin et al., 1994; Glasby, 2006; Wikipedia, 2009). The
consequences of course of such a theory, if true, could be
extraordinary, as earth's mantle becomes the inexhaustible
provider of the cheapest energy source on earth, by today's
standards, and shattering not only the oil-depletion myth but
also pointing out to oil-rich regions in places devoid as
prolific as before, because of belief of bio-
Figure 7: Dual drill string, from Reelwell.
Figure 8: Natural fractures in basement rock from White Tiger
field (from Chan et al., 2006).
Page 226 -- 3rd AMIREG Int'l Conf (2009)
genic origin. Alexandrovich Kudryavtsev (Kudryavtsev, 1951)
was the first to start the theory of abiotic generation of
hydrocarbons, in what has become the modern Russian-Ukrainian
theory of abyssal, abiotic petroleum (Kropotkin, 1986; Kenney
et al., 2002). However, Abbas (1996) starts the history as
early as 1877 by Mendeleev and provides a good overview as
well as pros and cons about the two points of view.
In principle, the abiotic theory states that under high
pressures (less than 5000 bar) and high temperatures (between
500 and 1500 degC) methane could be formed from reduced carbon
resulted from calcite. The process has been supported
theoretically, via thermodynamic analysis, and experimentally
(Kenney et al., 2002). Methane may also be formed from
volatile rich fluids resulting from partial melting of rocks
within earth's interior (National Academy Press, 2007).
Thermodynamics indicate that at 1300 K, CO2 and CO should be
the predominant carbon rich gases, while at lower temperatures
CH4 should be predominant (Eugster and Skippen, 1967), with
Symmonds et al., (1994) supporting the first argument by
measurements.
Strong support for this hypothesis is the fact that methane
and hydrocarbons are abundant in the outer solar system (Gold,
1979, 1984, 1985, 1993). There is reported evidence of abiotic
formation of complex organics from methane in Saturn's
satellite Titan's atmosphere (National Academy Press, 2007),
although it is stated that there may be no connection to
primitive earth, because at the low surface temperature of
Titan (at 46 K) all water is turned into ice. Methane, ethane
and acetylene have also been discovered in Comet C/1996 B2
Hyakutake (Mumma et al., 1996). The finding of very deep gas
reservoirs, down to almost 10000 m, with extremely high
success rates of more than 55%, has also been reported as
evidence of abiotic generation of hydrocarbons (Corsi, 2005).
Very recent works (Cathcart, 2007; Paropkari, 2008) have been
suggesting that we should be rethinking about oil exploration
strategies in view of the substantial evidence about abiotic
hydrocarbon origin. Kenney et al. (2002) analyzed
theoretically, via thermodynamic computations, the
possibilities for hydrocarbon generation at high pressures and
temperatures and showed that it is possible. They went on and
performed successful experiments, using a specially built
high pressure apparatus (Nikolaev and Shalimov, 1999) at
pressures of 50 kbar, temperatures to 1500 degC. Using only as
reagents solid iron oxide and 99.9% pure marble, wet with
triple distilled water, they were able to generate methane.
They reported that at pressures lower than 10 kbar only
methane was formed while at pressures greater than 30 kbar a
multi-component hydrocarbon mixture was formed including
methane, ethane, propane, n-alkanes as well as alkenes, in
distributions characteristic of natural petroleum. Scott et
al. (2004) have also reported in situ observations of
hydrocarbon generation via carbonate reduction at upper mantle
temperatures and pressures, forming methane from FeO,
CaCO3-calcite and water at temperatures ranging between 500
and 1500 degC and pressures between 50 and 110 kbar. The
authors were confident of the abiogenic theory of hydrocarbon
generation thus concluding that Earth's hydrocarbon budget is
much larger than it is currently thought.
Petroleum generation under hydrothermal conditions, with
certain metals or alloys used as catalysts, has been amply
demonstrated at lower temperatures and pressures. For e.g.
Horita and Bernt (1999) used a nickel-iron alloy, similar to
what could be found within earth's crust, to catalyze the
slow, under other conditions, reaction of methane generation
from dissolved bicarbonate, under hydrothermal conditions at
200 and 400 degC and 500 bar. Without the catalyst, no methane
was formed, concluding that abiogenic methane may be more
widespread than originally thought.
Proskurowski et al. (2008) suggested, through analysis of
components in hydrothermal oceanic vents that abiotic
synthesis in nature of hydrocarbon fluids may occur in the
presence of ultramafic rocks (which comprise mostly Earth's
mantle), water and moderate amounts of heat. On the other
hand, Konn et al. (2008) analyzing data from same and other
vents did not find conclusive evidence of the fact. He noted
that, although amounts of hydrocarbons attrib-
Page 227 -- 3rd AMIREG Int'l Conf (2009)
uted to abiogenic origin were found, their signature has been
difficult to characterize owing to the abundance of biogenic
material. This is not far from the findings of Robinson (1963)
who had noted at the time that the observed petroleum
composition cannot really be attributed to biological origin,
suggesting a primordial mixture to which bioproducts have been
added. Ji et al. (2008) also presented results of generating a
range of alcanes up to pentane, not only methane, from CO2 and
H2 in hydrothermal conditions with cobalt as catalyst at 300
degC and pressures as low as 300 bar. Szatmari (1989)
suggested the hypothesis of petroleum formation by
Fischer-Tropsch synthesis, which is distinct from the organic
and the inorganic coming from degassing theory of Gold.
Foustoukos and Seyfried (2004) also demonstrated the
acceleration of hydrocarbon production from CO2 and H2 with
the FischerTropsch reaction, using chromium and iron bearing
minerals as catalysts, at 390 degC and 450 bars. Recent reports
(Sherwood-Lollard et al., 2002) have identified traces of
abiotically derived hydrocarbons in Kidd Creek hard rock
mines. In the laboratory, abiotic synthesis of more complex
organic compounds has been reported in aqeous media (McCollom
et al., 1999).
Glasby (2006) gives a historical overview on the origin of
hydrocarbons. He dismisses both the Russian-Ukrainian theory
and the theory of gas degassing by Gold, as being non
thermodynamically sound. He does not discuss, however, the
Fischer-Tropsch type of reactions, pointed out above. Hence,
his work serves as a very good reference, but to the author's
opinion, the final arguments are not as strong as they should
have been. Interesting to note that he dismisses the Ukrainian
theory on the basis of better evidence for the origin of
higher hydrocarbons from organic matter, using better
techniques, and noting that the theory is even forgotten in
Ukraine, which is not true, as it has been recently
demonstrated (Kutcherov, 2007; Kitchka, 2007).
7. DISCUSSION
Humanity should be looking at all energy sources to cover
earth's energy budget, but we should not lose sight of the
fact that hydrocarbons play the most significant role in our
energy balance equation. Wells of the future will be
horizontal and multilateral wells with smart well technology,
meaning necessary hardware for producing when it is needed
while optimizing recovery (Rao, 2008), operated by top notch,
multidisciplinary people. As Robert Ryan, vice president of
global exploration at Chevron recently explained, 'the world
is full of resources the question is how we can apply
technology to make them energy resources" (Maksoud, 2009a). We
would add that we must do this while posing no threats to the
environment and maintaining sustainability.
The way forward will require "more creativity, more
innovation, and more integration" as mentioned by Ryan. There
was an interesting notion by Ryan, "Peak oil will be reached
when we reach peak technology, and peak technology will
determine when the world reaches peak energy" (Maksoud, 2009).
Thus, it is through technological advancement, ingenuity and
creativity and educating our people that we could extend the
oil depletion window. Of course, if the abiotic theory of oil
generation is true, then, the sky will be the limit and the
pressure will be on finding the oil, not on finding ways to
replace it.
8. CONCLUSIONS
An analysis has been presented of the current hydrocarbon
exploration trends, addressing the challenges that
oil-industry is facing to move into ultra deep waters and very
deep boreholes. Future breakthroughs for safer drilling into
very deep wells taping oil resources will be drilling to the
earth model where integration of drilling, completion and
seismic comes into play, with seismic interpretation while
drilling guiding drillers more intelligently.
A review of the recent and prior work has also been presented
of the theory of abiotic origin of hydrocarbons. Recent
theoretical and experimental evidence demonstrates the
possibil-
Page 228 -- 3rd AMIREG Int'l Conf (2009)
ity that hydrocarbons may have formed in the depths of the
earth. If the theory is substantiated further, then
oil-depletion becomes a myth and the industry must be ready to
face the new challenges of drilling even deeper, to the
basement rock, where huge oil fields may await to be
discovered, as White Tiger in Vietnam has proved. No matter,
though, of what the origin of hydrocarbons is, the sure trend
is that drilling depths will be increasing in the future and
the industry should be geared up and ready for meeting the
many challenges. In order to accomplish this, the industry
should continue to thrive in excellence, developing innovative
tools and techniques, while at the same time relying on top
quality people. Upstream petroleum industry has performed
wonders until today and all of this has been achieved through
people and excellent team work. The extra challenges the
industry will be facing make the demand even stronger for ever
more coordinated and multidisciplinary work and with extra
focus on innovations.
REFERENCES
[...snip...]
