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Experiment: Abiotic Oil (or at least Natural Gas) possible

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  • Experiment: Abiotic Oil (or at least Natural Gas) possible

    http://portal.acs.org/portal/acs/cor...region1&__uuid=

    ACS News Service Weekly PressPac: November 4, 2009

    New evidence supports 19th Century idea on formation of oil and gas

    “In Situ Diamond-Anvil Cell Observations of Methanogenesis at High Pressures
    and Temperatures”

    - Energy & Fuels

    Scientists in Washington, D.C. are reporting laboratory evidence supporting the possibility that some of Earth’s oil and natural gas may have formed in a way much different than the traditional process described in science textbooks.
    Their study is scheduled for Nov./Dec. issue of ACS’ Energy & Fuels, a bi-monthly publication: “In Situ Diamond-Anvil Cell Observations of Methanogenesis at High Pressures and Temperatures”. Anurag Sharma and colleagues note that the traditional process involves biology. Prehistoric plants died and changed into oil and gas while sandwiched between layers of rock in the hot, high-pressure environment deep below Earth’s surface. Some scientists, however, believe that oil and gas originated in other ways, including chemical reactions between carbon dioxide and hydrogen below Earth’ surface.
    The new study describes a test of that idea, which dates to at least 1877 and famous Russian chemist Dimitri Mendeelev. They combined ingredients for this so-called abiotic synthesis of methane, the main ingredient in natural gas, in a diamond-anvil cell and monitored in-situ the progress of the reaction. The diamond anvils can generate high pressures and temperatures similar to those that occur deep below Earth’s surface and allow for in-situ optical spectroscopy at the extreme environments. The results “strongly suggest” that some methane could form strictly from chemical reactions in a variety of chemical environments. This study further highlights the role of reaction pathways and fluid immiscibility in the extent of hydrocarbon formation at extreme conditions simulating deep subsurface.

  • #2
    Re: Experiment: Abiotic Oil (or at least Natural Gas) possible

    http://carnegiescience.edu/news/hydrocarbons_deep_earth

    Hydrocarbons in Deep Earth?


    Monday, July 27, 2009

    Video Press Release
    Washington, DC—The oil and gas that fuels our homes and cars started out as living organisms that died, were compressed, and heated under heavy layers of sediments in the Earth’s crust. Scientists have debated for years whether some of these hydrocarbons could also have been created deeper in the Earth and formed without organic matter. Now for the first time, scientists have found that ethaneand heavier hydrocarbons can be synthesized under the pressure-temperature conditions of the upper mantle —the layer of Earth under the crust and on top of the core. The research was conducted by scientists at the Carnegie Institution’s Geophysical Laboratory, with colleagues from Russia and Sweden, and is published in the July 26, advanced on-line issue of Nature Geoscience.

    Methane (CH4) is the main constituent of natural gas, while ethane (C2H6) is used as a petrochemical feedstock. Both of these hydrocarbons, and others associated with fuel, are called saturated hydrocarbons because they have simple, single bonds and are saturated with hydrogen. Using a diamond anvil cell and a laser heat source, the scientists first subjected methane to pressures exceeding 20 thousand times the atmospheric pressure at sea level and temperatures ranging from 1,300 F° to over 2,240 F°. These conditions mimic those found 40 to 95 miles deep inside the Earth. The methane reacted and formed ethane, propane, butane, molecular hydrogen, and graphite. The scientists then subjected ethane to the same conditions and it produced methane. The transformations suggest heavier hydrocarbons could exist deep down. The reversibility implies that the synthesis of saturated hydrocarbons is thermodynamically controlled and does not require organic matter.

    The scientists ruled out the possibility that catalysts used as part of the experimental apparatus were at work, but they acknowledge that catalysts could be involved in the deep Earth with its mix of compounds.

    “We were intrigued by previous experiments and theoretical predictions,” remarked Carnegie’s Alexander Goncharov a coauthor. “Experiments reported some years ago subjected methane to high pressures and temperatures and found that heavier hydrocarbons formed from methane under very similar pressure and temperature conditions. However, the molecules could not be identified and a distribution was likely. We overcame this problem with our improved laser-heating technique where we could cook larger volumes more uniformly. And we found that methane can be produced from ethane.”

    The hydrocarbon products did not change for many hours, but the tell-tale chemical signatures began to fade after a few days.

    Professor Kutcherov, a coauthor, put the finding into context: “The notion that hydrocarbons generated in the mantle migrate into the Earth’s crust and contribute to oil-and-gas reservoirs was promoted in Russia and Ukraine many years ago. The synthesis and stability of the compounds studied here as well as heavier hydrocarbons over the full range of conditions within the Earth’s mantle now need to be explored. In addition, the extent to which this ‘reduced’ carbon survives migration into the crust needs to be established (e.g., without being oxidized to CO2). These and related questions demonstrate the need for a new experimental and theoretical program to study the fate of carbon in the deep Earth.”

    __________________
    This research was supported by the U.S. Department of Energy, the National Nuclear Security Agency through the Carnegie/DOE Alliance Center, the National Science Foundation, the W.M. Keck Foundation, and the Carnegie Institution.

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