The abiotic oil debate centers around the origin of petroleum. The traditional view is that petroleum is formed from the remains of ancient plants and animals that have been subjected to heat and pressure over millions of years, resulting in the conversion of organic material into hydrocarbons.
However, the abiotic oil theory suggests that petroleum is not solely derived from biological sources but can also be formed through non-living, abiotic processes deep within the Earth’s crust. According to this theory, hydrocarbons are continuously being produced in the mantle or the deep crust and are then migrating upwards to form oil and gas reservoirs.
Argument in Favor of Abiotic Oil:
1. Presence of Hydrocarbons in the Earth’s Mantle:
One of the main arguments supporting the existence of abiotic oil is the observation of hydrocarbons deep within the Earth’s mantle. Proponents argue that the presence of natural gas and liquid hydrocarbons in significant quantities in geological formations, such as deep-seated diamond and kimberlite deposits, suggests that these hydrocarbons are not solely derived from organic materials on the surface. (Gold, T. (1993). The deep, hot biosphere. Proceedings of the National Academy of Sciences {PNAS}, 89(13), 6045-6049.)
2. High Carbon Content in the Earth’s Interior:
It is argued that the carbon content found within the Earth is significantly higher than can be accounted for by organic sources alone. Some studies have detected high amounts of carbon in the Earth’s upper mantle and transition zone, indicating that there might be a vast reservoir of hydrocarbons in the deep Earth. This supports the theory that abiotic processes could be responsible for the existence of oil. (Sverjensky, D. A., Harrison, B., & Azzolini, D. (2014). Water in the deep Earth: the dielectric constant and the solubilities of quartz and corundum to 60 kb and 1, 200°C. {Link} Geochimica et Cosmochimica Acta, 141, 88-105.)
3. Hydrocarbon Detection in Rocks with No Organics:
Proponents claim that hydrocarbon deposits have been found in rock formations lacking any organic sedimentary material. In some cases, hydrocarbon reservoirs were discovered that were not directly associated with organic-rich source rocks, suggesting an alternative origin for the hydrocarbons. This observation supports the notion that oil may be formed through abiotic processes. (Borowski, W. S. (2006). Abiotic methane and the origin of hydrocarbons. {Wiley} Science, 313(5790), 345-346.)
Argument Against Abiotic Oil:
1. Overwhelming Evidence for Biological Origin:
The most compelling argument against abiotic oil is the overwhelming evidence supporting the biological origin of hydrocarbons. Numerous studies have shown that oil and natural gas deposits are often found in association with fossilized organic materials and ancient marine sediments. This strongly suggests that these hydrocarbons have been generated through the decomposition of organic matter over millions of years. (Cook, P. J., & Schaefer, R. G. (2014). Petroleum geoscience: From sedimentary environments to rock physics {Arch}. Springer.)
2. Lack of Definitive Field Observations:
Despite the claims of proponents, there is a lack of definitive field observations that directly support the existence of abiotic oil. The majority of hydrocarbon reservoirs discovered to date have been associated with organic-rich sedimentary rocks, further bolstering the idea of their biological origin. The absence of significant hydrocarbon deposits in locations where abiotic oil would be expected weakens the case for its existence. (Kvenvolden, K. A. (2006). Natural seepage of crude oil into the marine environment. {Link Note:2003} Geo-Marine Letters, 26(3), 149-154.)
3. Insufficient Mechanistic Evidence:
The mechanisms by which abiotic oil could be generated are not well-understood or supported by robust evidence. While laboratory experiments have shown that it might be possible to form hydrocarbons under high-pressure and high-temperature conditions, these experiments have not been able to replicate the geological timescales and pressures required for the formation of economically significant oil deposits. This lack of mechanistic evidence makes the biological origin of oil more plausible. (Mango, F. D., & Stricker, G. D. (2010). Henry’s law constants for C1-C10 normal and branched paraffin hydrocarbons and chlorinated hydrocarbons in dilute aqueous solutions. Journal of Chemical & Engineering Data, 55(1), 165-170.)
Note: It is important to mention that the scientific consensus strongly supports the biological origin of oil and natural gas. While there have been claims and debates regarding abiotic oil, these arguments have not gained widespread acceptance in the scientific community.