Petroleum is believed by most to be formed only from the remains of buried plant or animal material. Abiotic oil however might be formed from the reaction of carbonates with iron oxide and water in the region called the mantle, deep in the Earth where there is a great amount of heat and pressure. Furthermore, the mantle is such a huge reservoir that the amount of reactants consumed in the reaction hasn't depleted it since the formation of the oil. In short, according to this idea petroleum is not a fossil fuel and has no intrinsic connection with plant or animal remains. Recent finds of liquid hydrocarbons on the moon Titan support the abiotic oil theory, beacuse the oil there was not made from organic material. Also, finds in the Atlantic Ocean show that oil is abiotic in nature.
There are two theories of abiotic oil:
- The "weak" abiotic oil theory: oil is abiotically formed, but at rates not higher than those that petroleum geologists assume for oil formation according to the conventional theory.
- The "strong" abiotic theory: oil is formed at a speed sufficient to replace the oil reservoirs as we deplete them, that is, at a rate something like 10,000 times faster than theorized in petroleum geology.
As optimistic as the idea of abiotic oil seems, the reality is that abiotic oil is widely considered to be scientifically unsupported in the West, although the Russian-Ukrainian theory claims to have successfully found many abiotic wells (as evidenced by Russian oil production), and refutes the biotic theory of oil completely. 
- J. F. Kenney An introduction to the modern petroleum science, and to the Russian-Ukrainian theory of deep, abiotic petroleum origins Russian Academy of Sciences - Joint Institute of The Physics of the Earth.
- Gold, Thomas (1999). The deep, hot biosphere. Copernicus Books. ISBN 0-387-98546-8.