This is the hypothesis that most of the oil and gas on Earth were formed inorganically, without the involvement of living organisms. ¹
Abiogenic oil and gas are different from biogenic oil and gas, which are derived from the decomposition of ancient plants and animals over millions of years. Biogenic oil and gas are more common in regions where there is a lot of organic matter preserved in sedimentary rocks, such as shale, sandstone, or limestone. Abiogenic oil and gas are more prevalent in regions where there is little or no organic matter, such as deep basaltic rocks or ultramafic rocks. ¹²
The abiogenic hypothesis has been proposed by several scientists throughout history, such as Alexander von Humboldt, Dmitri Mendeleev, Marcellin Berthelot, Abraham Gottlob Werner, Thomas Gold, Jack Kenney, Vladimir Kutherov, and others. ¹² They have suggested various mechanisms for how hydrocarbons can be generated abiotically in the Earth’s mantle or crust. Some of these mechanisms include:
- Thermal cracking: The application of high temperature (above 500°C) to organic matter can break it down into smaller molecules that can react with each other to form hydrocarbons. This process can occur naturally due to volcanic activity or tectonic movements that bring hot rocks to the surface. ²³
- Chemical reduction: The addition of hydrogen or other reducing agents to organic matter can lower its molecular weight and make it more susceptible to hydrocarbon formation. This process can occur naturally due to meteorite impacts or lightning strikes that provide hydrogen to the atmosphere or the surface. ²³
- Hydrothermal venting: The presence of water at high pressure (above 1000 bar) near volcanic vents can provide a source of energy for chemical reactions that produce hydrocarbons from carbon dioxide and water. This process can occur naturally due to geothermal activity that creates hot springs or geysers on Earth’s surface or underground. ²³
The abiogenic hypothesis has some advantages over the biogenic hypothesis for explaining some aspects of oil and gas formation. For example:
- It can account for the large amounts of oil and gas found in deep basaltic rocks or ultramafic rocks that are not associated with any fossils or organic matter.
- It can explain why oil and gas have similar chemical compositions regardless of their source rocks.
- It can predict where oil and gas deposits are likely to be located based on geological features such as faults, fractures, sills, or basins.
However, the abiogenic hypothesis also faces some challenges and limitations for explaining other aspects of oil and gas formation. For example:
- It cannot account for the diversity of hydrocarbon structures and properties observed in different types of reservoirs.
- It cannot explain why some regions have more biogenic than abiotic sources of oil and gas.
- It cannot predict how much oil and gas will be produced from a given reservoir based on its size or depth.
Therefore, the abiogenic hypothesis is not a complete theory but rather a partial explanation that needs further testing and verification by empirical evidence.
Source: Conversation with Bing, 1/10/2024
(1) Abiogenic petroleum origin – Wikipedia. https://en.wikipedia.org/wiki/Abiogenic_petroleum_origin.
(2) Abiotic Oil and Gas: A Theory That Refuses To Vanish. https://peakoil.com/geology/abiotic-oil-and-gas-a-theory-that-refuses-to-vanish.
(3) Abiogenic Deep Origin of Hydrocarbons and Oil and Gas Deposits …. https://www.intechopen.com/chapters/41889.
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