About Opentopia
Opentopia Directory Encyclopedia Tools

Abiogenic petroleum origin

Encyclopedia : A : AB : ABI : Abiogenic petroleum origin

The hypothesis of abiogenic petroleum origin holds that petroleum was formed by primordial non-biological processes deep in the earth's crust and mantle. It contradicts the more widely-held view that petroleum is a fossil fuel produced from the buried remains of ancient living organisms. The French chemist Marcellin Berthelot and the Russian chemist Dmitri Mendeleev proposed it in the nineteenth century, and saw a revival in the last half of the twentieth century by Russian and Ukrainian scientists.

The modern scientific consensus on abiogenic origin petroleum is that while there is evidence for it, most modern geologists do not support this for the vast majority of petroleum deposits within the Earth.[[Citing sources citation needed]]

The deep biogenic petroleum theory proposes, mostly after the work of Thomas Gold, that the ‘’deep hot biosphere’’ may be the source of some petroleum alteration and for the observation of biomarkers in produced petroleum.

Other planets of the solar system or their moons have large amounts of methane and other hydrocarbons, presumably not of biological origin.

Contents

Foundations of the hypothesis

The hypothesis is founded primarily upon; The orthodox biogenic theories of petroleum accept that petroleum accumulations within the crust are remnants of buried plant and animal life. This is converted into petroleum hydrocarbons via diagenesis and the incipient stages of metamorphism. Organic matter consisting of dead plants and animals is deposited and buried. Accumulating sediments compress the material over geologic time scales. At a depth of several hundred meters, heat and pressure convert it to bitumens and kerogens. Time and temperature crack kerogens into the hydrocarbons that comprise petroleum in a process called catagenesis.

Abiogenic theories consider that within the mantle much carbon exists as hydrocarbon molecules, chiefly methane, and as carbon dioxide and carbonates. The full suite of hydrocarbons found in petroleum is generated at depth by abiogenic processes,[#endnote_Kenney2002] and therefore shallow petroleum deposits come from the upward displacement of those hydrocarbons. When this material passes up through temperatures at which extremophile microbes can survive some of it is consumed and modified. The material continues to migrate upwards through the crust until they are trapped by impermeable strata, where it forms reservoirs. Another formulation of abiogenic origin theory sees microbial life strictly as a contaminant, unnecessary to account for any "biomarkers" supposedly supporting biogenic origins.[#endnote_Kenney2001]

Mechanism of abiogenic petroleum

The proposed mechanism by which abiogenic petroleum is formed was first proposed by the Ukrainian scientist, Prof. Emmanuil B. Chekaliuk in 1967. He proposed that petroleum could be formed at high temperatures and pressures from inorganic carbon in the form of carbon dioxide, hydrogen and/or methane.

This mechanism is supported by several lines of evidence which are accepted by modern scientific literature. This involves synthesis of oil within the crust via catalysis by chemically reductive rocks. A proposed mechanism for the formation of inorganic hydrocarbons[#endnote_Keith2005] is via natural analogs of the Fischer-Tropsch process known as the serpentinite mechanism or the serpentinite process [#endnote_Szatmari][#endnote_Charlou2005].

[CH_4 + \begin \frac \endO_2 \rarr 2 H_2 + CO]
[(2n+1)H_2 + nCO \rarr C_nH_ + nH_2O]
Serpentinites are ideal rocks to host this process as they are formed from peridotites and dunites, rocks which contain greater than 80% olivine and usually a percentage of Fe-Ti spinel minerals. Most olivines also contain high nickel concentrations (up to several percent) and may also contain chromite or chromium as a contaminant in olivine, providing the needed transition metals.

However, serpentinite synthesis and spinel cracking reactions require hydrothermal alteration of pristine peridotite-dunite, which is a finite process intrinsically related to metamorphism, and further, requires significant addition of water. Serpentinite is unstable at mantle temperatures and is readily dehydrated to granulite, amphibolite, talc-schist and even eclogite. This suggests that methanogenesis in the presence of serpentinites is restricted in space and time to mid-ocean ridges and upper levels of subduction zones. Oil cannot therefore be created by this process in intracratonic regions.

Serpentinite synthesis

The chemical basis for the abiotic petroleum process is the serpentinization of peridotite, beginning with methanogenesis via hydrolysis of olivine into serpentine in the presence of carbon dioxide[#endnote_Charlou2005]. Olivine, composed of Forsterite and Fayalite metamorphoses into serpentine, magnetite and silica by the following reactions, with silica from fayalite decomposition (reaction 1a) feeding into the forsterite reaction (1b).

Reaction 1a:
Fayalite + water → Magnetite + aquaeous silica

[3Fe_2SiO_4 + 2H_2O \rarr 2Fe_3O_4 + 3SiO_2 ]
Reaction 1b:
Forsterite + aqueous silica → Serpentinite
[3Mg_2SiO_4 + SiO_2 + 2H_2O \rarr 2Mg_3[Si_2O_5(OH_4)]]
When this reaction occurs in the presence of dissolved carbon dioxide (carbonic acid) at temperatures above 500°C Reaction 2a takes place.

Reaction 2a:
Olivine + Water + Carbonic acid → Serpentine + Magnetite + Methane

[3(Fe,Mg)_2SiO_4 + nH_2O + HCO_3 \rarr 2Mg_3[Si_2O_5(OH_4)] + 2Fe_3O_4 + H_2O + CH_4]
However, reaction 2(b) is just as likely, and supported by the presence of abundant talc-carbonate schists and magnesite stringer veins in many serpentinised peridotites;

Reaction 2b:
Olivine + Water + Carbonic acid → Serpentine + Magnetite + Magnesite + Silica

[4(Fe,Mg)_2SiO_4 + nH_2O + HCO_3 \rarr 2Mg_3[Si_2O_5(OH_4)] + 2Fe_3O_4 + 2MgCO_3 + SiO_2 + H_2O]
The upgrading of methane to higher n-alkane hydrocarbons is via dehydrogenation of methane in the presence of catalyst transition metals (e.g. Fe, Ni). This can be termed spinel hydrolysis.

Spinel polymerization mechanism

Magnetite, chromite and ilmenite are Fe-spinel group minerals found in many rocks but rarely as a major component in non-ultramafic rocks. In these rocks, high concentrations of magmatic magnetite, chromite and ilmenite provide a reduced matrix which may allow abiotic cracking of methane to higher hydrocarbons during hydrothermal events.

Chemically reduced rocks are required to drive this reaction and high temperatures are required to allow methane to be polymerized to ethane. Note that reaction 1a, above, also creates magnetite.

Reaction 3:
''Methane + Magnetite → Ethane + Hematite

[nCH_4 + nFe_3O_4 + nH_2O \rarr C_2H_6 + Fe_2O_3 + HCO_3 + H^+]
Reaction 3 results in n-alkane hydrocarbons, including linear saturated hydrocarbons, alcohols, aldehydes, ketones, aromatics, and cyclic compounds.[#endnote_Charlou2005]

Deep sea vent biogeochemical cycle diagram
Enlarge
Deep sea vent biogeochemical cycle diagram

Evidence from petroleum geochemistry

If the above mechanism for inorganic petroleum genesis is active and prevalent within the Earth crust and the abiogenic theory holds true, the geochemistry of petroleum deposits within the Earth’s crust should reflect this mechanism of formation.

The geochemistry of petroleum deposits has been widely and deeply studied by oil companies and academia for more than a century in order to elucidate the origin of petroleum and develop predictive scientific models. Certain findings of this research can be used to interpret petroleum as being either of biogenic or abiogenic origin. These include biomarker chemicals, the optical activity of oils, chirality and the trace metal abundances of oils.

Isotopic evidence

Methane is ubiquitous in crustal fluid and gas [#endnote_Lollar2006]. Research continues to attempt to characterise crustal sources of methane as biogenic or abiogenic using carbon isotope fractionation of observed gases (Lollar & Sherwood 2006). There are few clear examples of abiogenic methane-ethane-butane, as the same processes favor enrichment of light isotopes in all chemical reactions, whether organic or inorganic. δ13C of methane overlaps that of inorganic carbonate and graphite in the crust, which are heavily depleted in 12C, and attain this by isotopic fractionation during metamorphic reactions.

One argument for abiogenic oil cites the high carbon depletion of methane as stemming from the observed carbon isotope depletion with depth in the crust. However, diamonds, which are definitively of mantle origin, are not as depleted as methane, which implies that methane carbon isotope fractionation is not controlled by mantle values. [#endnote_Mello2005]

Helium isotope geochemistry is a clear indicator of mantle source within gases. Within the major precambrian shield there is no evidence of mantle helium in gases or groundwaters, which disproves the theory of continued outgassing of primordial methane and helium along structures in the Precambrian basement. Furthermore, there are few examples of primordial helium or mantle helium trapped within oil and gas occurrences.

Helium trapped within most petroleum occurrences, such as the occurrence in Texas, is of a distinctly crustal character with an Ra ratio of less than 0.0001 that of the atmosphere.

Biomarker chemicals

Certain chemicals found in naturally occurring petroleum contain chemical and structural similarities to compounds found within many living organisms. These include terpenoids, terpenes, pristane, phytane, cholestane, chlorins and porphyrins, which are large, chelating molecules in the same family as heme and chlorophyll. Materials which suggest certain biological processes include tetracyclic diterpane and oleanane.

The presence of these chemicals in crude oil is assumed to be as a result of the inclusion of biological material in the oil. This is predicated upon the theory that these chemicals are released by kerogen during the production of hydrocarbon oils.

However, since the advent of abiogenic theory, the veracity of these assumptions has been called into question and new lines of evidence used to provide alternative explanations.

Odd-number carbon abundance

Members of the n-alkane series found in petroleum have a slightly greater abundance of odd-numbered carbon chains (propane, pentane, etc.) Likewise, linear carbohydrate molecules in living systems exhibit the same preference for odd carbon numbers.

All mixtures of linear hydrocarbon chains, be they artificial, natural or biological, exhibit this tendency. It arises from the geometry of the covalent bond in linear molecules, so the greater abundances of odd-numbered hydrocarbons need not be of biological origin.

Trace metals

Nickel (Ni), vanadium (V), lead (Pb), arsenic (As), cadmium (Cd), mercury (Hg) and others metals frequently occur in oils. Some heavy crude oils, such as Venezuelan heavy crude have up to 45% vanadium pentoxide content in their ash, high enough that it is a commercial source for vanadium. These metals are common in Earth's mantle, thus their compounds in oils are often called as abiomarkers.

Analysis of 22 trace elements in 77 oils correlate significantly better with chondrite, serpentinized fertile mantle peridotite, and the primitive mantle than with oceanic or continental crust, and shows no correlation with seawater. [#endnote_Szatmari]

Reduced carbon

Petroleum is composed mainly of n-alkanes. Sir Robert Robinson studied the chemical makeup of natural petroleum oils in great detail, and concluded that they were mostly far too hydrogen-rich to be a likely product of the decay of plant debris.

Olefins, the unsaturated hydrocarbons, would have been expected to predominate by far in any material that was derived in that way. He also wrote: "Petroleum ... [seems to be] a primordial hydrocarbon mixture into which bio-products have been added."

The presence of low-oxygen and hydroxyl-poor hydrocarbons in natural living media is supported by the presence of natural waxes (n=30+), oils (n=20+) and lipids in both plant matter and animal matter, for instance fats in phytoplankton, zooplankon and so on. These oils and waxes, however, occur in quantities too small to significantly affect the overall hydrogen/carbon ratio of biological materials.

Geological framework

The proposed mechanism for abiogenic petroleum production is robust in theory, leaving aside ambiguous geochemical evidence. The abiogenic theory on the origin of petroleum seeks to explain the origin of commercial accumulations of petrochemicals via the chemical mechanism of serpentinite catalysis.

The geological observations which are used to support the abiogenic origin of petrochemical deposits should be evaluated on a case-by-case basis for each hydrocarbon deposit, with the presence of no one line of evidence used in isolation to infer genetic conclusions when equivocal or contradictory evidence is available.

The geological observations proposed for the abiogenic theory are presented below, followed by investigation of several key deposits on a case by case basis to evaluate their genesis.

Direct observations

The following are the direct tests of the abiogenic hypothesis of petroleum or impartial evidence generated by observations of the Earth which can be used to argue the theory for or against, and is presented as such.
Drilling of the Siljan Ring with a 7,500m borehole penetrated the lowest reservoirs. Hydrocarbons were found, though in an economically unviable form of sludge. It was proposed that the eight barrels of oil produced were from the diesel fuel based drilling fluid used to do the drilling, but the diesel was demonstrated to be not of the kind of oil found in the shaft.[[Citing sources citation needed]] To be safe, a second hole was drilled a few miles away with no diesel fuel based drilling fluid and this also produced more of the same sludge, though it was impossible to determine how much of it there was.
  • Methanogenesis of groundwaters associated with ultramafic dykes and serpentinites, South Island of New Zealand
  • Methane outflows common from drillholes within large Archaean serpentinised olivine adcumulate bodies, such as the Honeymoon Well complex, Yakabindie ultramafic, Mt Clifford dunite, in the Yilgarn Craton, Western Australia.
  • Direct observation of bacterial mats and fracture-fill carbonate and humin of bacterial origin in deep boreholes in Iran, Australia[#endnote_Bons2004], Sweden and Canada
  • Presence of deep-dwelling microbes in the Lechuguilla cave complex, New Mexico

    • Example abiogenic deposits

    Supergiant fields such as the Athabasca Tar Sands (Canada), Orinoco Heavy Oil Belt (Venezuela) and the Ghawar Field (Saudi Arabia) are good examples that have been interpreted as having been formed by abiogenic oils. This interpretation is based mostly on perceived deficiency in source rock volumes.

    The White Tiger oil field in Vietnam has been proposed as an example of abiogenic oil because it is found 1000 meters within crystalline basement rock.[#endnote_Brown2005]. However, others argue that it contains biogenic oil which leaked into the basement horst from conventional source rocks at depth within the Cuu Long basin. [#endnote_Cuulong1]. (

    The geological argument for abiogenic oil

    Given the known occurrence of methane and the probable catalysis of methane into higher atomic weight hydrocarbon molecules, the abiogenic hypothesis considers the following to be key observations in support;

    Incidental evidence

    The proponents of abiogenic oil use several arguments which draw on a variety of natural phenomena in order to support the hypothesis

    The geological argument against

    Key arguments against the serpentinite mechanism as being the major source of hydrocarbon deposits within the crust are;

    Arguments against the incidental evidence

    History of abiogenic theory

    The abiogenic petroleum theory was founded upon several archaic interpretations of geology which stem from early 19th century notions of magmatism (which at the time was attributed to sulfur fires and bitumen burning underground) and of petroleum, which was seen by many to fuel volcanoes. Indeed, Wernerian appreciation of basalts at times saw them as solidified oils or bitumen. While these notions have been disabused, the basic notion that petroleum is associated with magmatism has persisted. The chief proponents of what would become the abiogenic theory were Mendeleev[#endnote_Mendeleev] and Berthelot.

    Russian geologist Nikolai Alexandrovitch Kudryavtsev was the first to propose the modern abiotic theory of petroleum in 1951. He analyzed the geology of the Athabasca Tar Sands in Alberta, Canada and concluded that no "source rocks" could form the enormous volume of hydrocarbons, and that therefore the most plausible explanation is abiotic deep petroleum. However, humic coals have been proposed for the source rocks by [Stanton (2005)].

    Although this theory is supported by geologists in Russia and Ukraine, it has recently begun to receive attention in the West, where the biogenic petroleum theory is still believed by the vast majority of petroleum geologists. Kudryavtsev's work was continued by many Russian researchers — Petr N. Kropotkin, Vladimir B. Porfir'ev, Emmanuil B. Chekaliuk, Vladilen A. Krayushkin, Georgi E. Boyko, Georgi I. Voitov, Grygori N. Dolenko, Iona V. Greenberg, Nikolai S. Beskrovny, Victor F. Linetsky and many others.

    The theory is receiving attention from Western geologists, as indicated by the one day just prior to the June 2005 AAPG annual meeting in Calgary, Alberta.

    Astrophysicist Thomas Gold[#endnote_Gold1999] was one of the abiogenic theory's most prominent proponents in recent years in the West. Thomas Gold died in 2004, with apparently none of his students following up on his research. Conspiracist Joe Vialls [#endnote_www.vialls.com.228] died in 2005. The passing of the torch may go to Dr. Jerome R. Corsi, author of "Black Gold Stranglehold", or Dr. Jack Kenney of Gas Resources Corporation[#endnote_Kenney2][#endnote_Kenney2001][#endnote_Kenney2002]. Nevertheless, the theory has received continued attention in the media and scientific organizations (note external links).

    Petroleum origin, peak oil, and politics

    Many aspects of the abiogenic theory were developed in the former Soviet Union by Russian and Ukrainian scientists during the Cold War. Some proponents see a pro-Western bias in the promotion of the biogenic theory. Thus, in addition to the scientific merits of competing hypothoses, political and economic considerations often influence discussions of petroleum origins.

    The topic of the origin of petroleum is also linked to discussions of projected declines in petroleum production, variously referred to as "peak oil" or "Hubbert's peak". The abiogenic theory stands in contrast to that of Peak Oil, which presumes a fixed and dwindling supply of oil that was formed through biological processes.

    Some environmentalists accuse abiogenic theory supporters of a "cornucopian" worldview. They claim that such a view incorrectly sees no limits to exploitation of petroleum supplies while simultaneously ignoring potential consequences of petroleum consumption such as global warming. Conversely, some supporters of the abiogenic theory accuse their opponents of an unwarranted Malthusian viewpoint that needlessly limits the use of hydrocarbons as an energy source and artificially inflates oil prices.

    Independent of whether massive hydrocarbon reserves exist deep in the crust, they are unattainable in the short term. Additionally, oil wells are being drilled down to depths of 10 kilometres, just shy of the world record of 12km set by the Kola Superdeep Borehole in the Siberian Craton. Thus the "deep reservoirs" of Gold et al. are being tested successfully according to biogenic models of petroleum occurrence.

    Considering the dominance of the biogenic origin theory in the exploration industry, new oil discoveries based on abiogenic theory may be slow in coming. The ASPO predicts that global oil production will peak in 2007, while some other organizations such as the USGS pick as late as 20 years later. If it ever does happen, there will be serious economic ramifications. For this reason, as well as concerns about global warming, development of nuclear power and renewable energy sources continues at an accelerating pace.

    These aspects of the controversy may be seen in many of the online articles in the External links section below.

    State of current research

    Currently there is little direct research on abiogenic petroleum or experimental studies into the synthesis of abiogenic methane. However, several research areas, mostly related to astrobiology and the deep microbial biosphere and serpentinite reactions, continue to provide insight into the contribution of abiogenic hydrocarbons into petroleum accumulations. Similarly, research into the deep microbial hypothesis of hydrocarbon generation is advancing as part of the attempt to investigate the concept of panspermia and astrobiology, specifically using deep microbial life as an analog for life on Mars. Research applicable to deep microbial petroleum theories includes The abiogenic origin of petroleum has recently been reviewed in detail by Glasby (2006) and shown to be invalid on a number of counts.

    See also

    References

    Bibliography

    1. ↑  Mendeleev, D., 1877. L'origine du petrole. Revue Scientifique, 2e Ser., VIII, p. 409-416.
    2. ↑ 
    3. ↑  Kenney, J.F., Karpov I.K., et al. 2002. The Prohibition of Hydrocarbon Genesis at Low Pressures. Unpublished research. [Article Link]

    Peer reviewed journals

    1. ↑  [Article link]
    2. ↑  [Article link]
    3. ↑ 
    4. ↑  DOI:[10.1038/415312a]
    5. ↑  Szatmari, P, Da Fonseca, T, and Miekeley, N. Trace Element Evidence for Major Contribution to Commercial Oils by Serpentinizing Mantle Peridotites. AAPG Research Conference, Calgary, Canada, 2005. [Abstract]
    6. ↑  Kitchka, A., 2005. Juvenile Petroleum Pathway: From Fluid Inclusions via Tectonic Pathways to Oil Fields. AAPG Research Conference, Calgary, Canada, 2005.[Abstract]
    7. ↑  J. L. Charlou, J. P. Donval, P. Jean-Baptiste, D. Levaché, Y. Fouquet, J. P. Foucher, P. Cochonat, 2005. Abiogenic Petroleum Generated by Serpentinization of Oceanic Mantellic Rocks. AAPG Research Conference, Calgary, Canada, 2005.
    8. ↑  M. R. Mello and J. M. Moldowan (2005). Petroleum: To Be Or Not To Be Abiogenic. AAPG Research Conference, Calgary, Canada, 2005. [Abstract]
    9. ↑  Keith, S., Swan, M. 2005. Hydrothermal Hydrocarbons. AAPG Research Conference, Calgary, Canada, 2005. [Abstract]
    10. ↑ 
    11. ↑ 
    12. ↑  [Abstract]
    13. ↑  Lollar, Sherwood et al. 2002. Abiogenic formation of alkanes in the Earth's crust as a minor source for global hydrocarbon reservoirs. Nature, 416, pp522-524. [Abstract]
    14. ↑  Lollar, Sherwood et al. 2006. Unravelling abiogenic and biogenic sources of methane, Chemical Geology. [Paper (pdf)]
    15. ↑ Valentin, J., 2004. Isotopic, organic and inorganic geochemistry of the Idrija mercury deposit, Slovenia: constraints on the formation of the Hg-PAH association. PhD Thesis, Unpublished, Univerity of Lausanne, Switzerland.[Abstract]
    16. ↑  Zhmur S.L., 2002. Shungites of Karelia as Model for Carbon Hondrites Formation. Journal of Astrobiology. [Paper (pdf)]
    17. ↑  Dutkiewicz, A., Volk A., Ridley J., George S., 2003. Biomarkers, brines, and oil in the Mesoproterozoic, Roper Superbasin, Australia. Geology; v. 31; p. 981-984 [Abstract]
    18. ↑  Bons P., et al. 2004. Fossil microbes in late proterozoic fibrous calcite veins from Arkaroola, South Australia. Geological Society of America Abstracts with Programs, Vol. 36, No. 5, p. 475
    19. ↑  Stanton, M.S., 2004. Origin of the Lower Cretaceous Heavy Oils ("Tar Sands") of Alberta. AAPG Search and Discovery Article #10071 (2004) [Article link (pdf)]
    20. ↑  B. M. Valyaev, S. A. Leonov, G. A. Titkov, and M. Yu. Chudetsky, 2005. Conceptions and Indicators of the Abiogenic Oil and Gas Origin and Its Significance. AAPG Conference, Calgary, Canada 2005. [Abstract]
    21. ↑  Dow, W.G., 2005. The Petroleum System Paradigm and the Biogenic Origin of Oil and Gas. AAPG Conference, Calgary, Canada 2005. [Abstract] discussion of oil genesis, optical axis shifts, and the CuuLong / White Tiger field.
    22. ↑ Seewald J., Whelan J., 2005. Isotopic and Chemical Composition of Natural Gas from the Potato Hills Field, Southeastern Oklahoma: Evidence for an Abiogenic Origin? AAPG Conference, Calgary, Canada 2005. [Abstract]
    23. ↑ Barker C., 2005. The Complementary Roles of Kinetics and Thermodynamics in the Generation and Preservation of Oil and Gas. AAPG Conference, Calgary, Canada 2005. [Abstract]
    24. Glasby, G.P., 2006. Abiogenic origin of hydrocarbons: An historical overview. Resource Geology 56, 83-96

    External links section

     

    From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating.
    All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details.

    Search Titles
    0123456789
    ABCDEFGHIJ
    KLMNOPQRST
    UVWXYZ?

    E-mail this article to:

    Personal Message: