Abiogenic Petroleum Origin

Abiogenic petroleum origin is an obsolete hypothesis that was proposed as an alternative mechanism of petroleum origin.

According to the abiogenic hypothesis, petroleum was formed from deep carbon deposits, perhaps dating to the formation of the Earth. Supporters of the abiogenic hypothesis suggest that a great deal more petroleum exists on Earth than commonly thought, and that petroleum may originate from carbon-bearing fluids that migrate upward from the mantle. The presence (oceans) of methane on Saturn's moon Titan and in the atmospheres of Jupiter, Saturn, Uranus and Neptune is cited as evidence of the formation of hydrocarbons without biology.

The hypothesis was first proposed by Georg Agricola in the 16th century and various abiogenic hypotheses were proposed in the 19th century, most notably by Alexander von Humboldt, the Russian chemist Dmitri Mendeleev and the French chemist Marcellin Berthelot. Abiogenic hypotheses were revived in the last half of the 20th century by Soviet scientists who had little influence outside the Soviet Union because most of their research was published in Russian. The hypothesis was re-defined and made popular in the West by Thomas Gold who published all his research in English.

Although the abiogenic hypothesis was accepted by many geologists in the former Soviet Union, it fell out of favor at the end of the 20th century because it never made any useful prediction for the discovery of oil deposits. The abiogenic origin of petroleum has also recently been reviewed in detail by Glasby, who raises a number of objections, including that there is no direct evidence to date of abiogenic petroleum (liquid crude oil and long-chain hydrocarbon compounds). Geologists now consider the abiogenic formation of petroleum scientifically unsupported, and they agree that petroleum is formed from organic material. However, the abiogenic theory can't be dismissed yet because the mainstream theory still has to be established conclusively.

It has been recently discovered that thermophilic bacteria, in the sea bottom and in cooling magma, produce methane and hydrocarbon gases, but studies indicate they are not produced in commercially significant quantities (i.e. in extracted hydrocarbon gases, the median abiogenic hydrocarbon content is 0.02%, or 1 part in 5,000).