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

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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. 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.

Source: American Chemical Society