For years, geology textbooks have described the 'Biogenic' theory - what is thought to be the only way oil and natural gas form in the Earth's subsurface. It is simply a product of compression and heating of ancient organic materials over geological time. Recently, scientists from the Carnegie Institution in Washington, DC have produced laboratory results that "strongly suggest" that oil and gas can originate in other ways - including chemical reactions between carbon dioxide and hydrogen beneath the Earth's surface.

This chemical reaction theory - known as the 'Abiogenic' theory - is not entirely new. It was also proposed in 1877 by the famous Russian chemist Dimitri Mendeelev - but to date no tests have been able to prove it, so the theory remains very much a minority opinion among Western geologists.

To test the hypothesis, the Carnegie Institute scientists 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.

The study is scheduled for Nov./Dec. issue of ACS' Energy & Fuels.

Source: http://pubs.acs.org/stoken/presspac/presspac/full/10.1021/ef9006017