The Origin of Oil

by Dr. Andrew A. Snelling on December 27, 2006; last featured March 8, 2022
Featured in Answers Magazine

For more than 100 years, oil has been the “black gold” that has fueled transport vehicles and powered global economic growth and prosperity. So how does oil form, and what is its origin?

Basic Oil Geology

Oil deposits are usually found in sedimentary rocks. Such rocks formed as sand, silt, and clay grains were eroded from land surfaces and carried by moving water to be deposited in sediment layers. As these sediment layers dried, chemicals from the water formed natural cements to bind the sediment grains into hard rocks.

Pools of oil are found in underground traps where the host sedimentary rock layers have been folded and/or faulted. The host sedimentary or reservoir rock is still porous enough for the oil to accumulate in spaces between the sediment grains. The oil usually hasn’t formed in the reservoir rock but has been generated in source rock and subsequently migrated through the sedimentary rock layers until trapped.

The Origin and Chemistry of Oil

Most scientists agree that hydrocarbons (oil and natural gas) are of organic origin. A few, however, maintain that some natural gas could have formed deep within the earth, where heat melting the rocks may have generated it inorganically.1 Nevertheless, the weight of evidence favors an organic origin, most petroleum coming from plants and perhaps also animals, which were buried and fossilized in sedimentary source rocks.2 The petroleum was then chemically altered into crude oil and gas.

The chemistry of oil provides crucial clues as to its origin. Petroleum is a complex mixture of organic compounds. One such chemical in crude oils is called porphyrin:

Petroleum porphyrins … have been identified in a sufficient number of sediments and crude oils to establish a wide distribution of the geochemical fossils.3

They are also found in plants and animal blood4 (see sidebar Porphyrins).


Porphyrins are organic molecules that are structurally very similar to both chlorophyll in plants and hemoglobin in animal blood.1 They are classified as tetrapyrrole compounds and often contain metals such as nickel and vanadium.2 Porphyrins are readily destroyed by oxidizing conditions (oxygen) and by heat.3 Thus geologists maintain that the porphyrins in crude oils are evidence of the petroleum source rocks having been deposited under reducing conditions:

The origin of petroleum is within an anaerobic and reducing environment. The presence of porphyrins in some petroleums means that anaerobic conditions developed early in the life of such petroleums, for chlorophyll derivatives, such as porphyrins, are easily and rapidly oxidized and decomposed under aerobic conditions.4


  1. McQueen, D. R., “The chemistry of oil—explained by Flood geology,” Impact #155, Institute for Creation Research, Santee, California, 1986.
  2. Tissot, B. P., and Welte, D. H., Petroleum Formation and Occurrence, 2nd ed., Springer-Verlag, Berlin, pp. 409–410, 1984.
  3. Russell, W. L., Principles of Petroleum Geology, 2nd ed., McGraw-Hill Book Company, New York, p. 25, 1960.
  4. Levorsen, p. 502.

The Significance of Oil Chemistry

It is very significant that porphyrin molecules break apart rapidly in the presence of oxygen and heat.5 Therefore, the fact that porphyrins are still present in crude oils today must mean that the petroleum source rocks and the plant (and animal) fossils in them had to have been kept from the presence of oxygen when they were deposited and buried. There are two ways this could have been achieved:

1. The sedimentary rocks were deposited under oxygen deficient (or reducing) conditions.6

2. The sedimentary rocks were deposited so rapidly that no oxygen could destroy the porphyrins in the plant and animal fossils.7

However, even where sedimentation is relatively rapid by today’s standards, such as in river deltas in coastal zones, conditions are still oxidizing.8 Thus, to preserve organic matter containing porphyrins requires its slower degradation in the absence of oxygen, such as in the Black Sea today.9 But such environments are too rare to explain the presence of porphyrins in all the many petroleum deposits found around the world. The only consistent explanation is the catastrophic sedimentation that occurred during the worldwide Genesis Flood. Tons of vegetation and animals were violently uprooted and killed respectively, so that huge amounts of organic matter were buried so rapidly that the porphyrins in it were removed from the oxidizing agents which could have destroyed them.

The amounts of porphyrins found in crude oils vary from traces to 0.04% (or 400 parts per million).10 Experiments have produced a concentration of 0.5% porphyrin (of the type found in crude oils) from plant material in just one day,11 so it doesn’t take millions of years to produce the small amounts of porphyrins found in crude oils. Indeed, a crude oil porphyrin can be made from plant chlorophyll in less than 12 hours. However, other experiments have shown that plant porphyrin breaks down in as little as three days when exposed to temperatures of only 410°F (210°C) for only 12 hours. Therefore, the petroleum source rocks and the crude oils generated from them can’t have been deeply buried to such temperatures for millions of years.

The Origin & Rate of Oil Formation

Crude oils themselves do not take long to be generated from appropriate organic matter. Most petroleum geologists believe crude oils form mostly from plant material, such as diatoms (single-celled marine and freshwater photosynthetic organisms)12 and beds of coal (huge fossilized masses of plant debris).13 The latter is believed to be the source of most Australian crude oils and natural gas because coal beds are in the same sequences of sedimentary rock layers as the petroleum reservoir rocks.14 Thus, for example, it has been demonstrated in the laboratory that moderate heating of the brown coals of the Gippsland Basin of Victoria, Australia, to simulate their rapid deeper burial, will generate crude oil and natural gas similar to that found in reservoir rocks offshore in only 2–5 days.15

However, because porphyrins are also found in animal blood, it is possible some crude oils may have been derived from the animals also buried and fossilized in many sedimentary rock layers. Indeed, animal slaughterhouse wastes are now routinely converted within two hours into high-quality oil and high-calcium powdered and potent liquid fertilizers, in a commercial thermal conversion process plant16 (see sidebar Animal Wastes Become Oil).


All the available evidence points to a recent catastrophic origin for the world’s vast oil deposits, from plant and other organic debris, consistent with the biblical account of earth history. Vast forests grew on land and water surfaces17 in the pre-Flood world, and the oceans teemed with diatoms and other tiny photosynthetic organisms. Then during the global Flood cataclysm, the forests were uprooted and swept away. Huge masses of plant debris were rapidly buried in what thus became coal beds, and organic matter generally was dispersed throughout the many catastrophically deposited sedimentary rock layers. The coal beds and fossiliferous sediment layers became deeply buried as the Flood progressed. As a result, the temperatures in them increased sufficiently to rapidly generate crude oils and natural gas from the organic matter in them. These subsequently migrated until they were trapped in reservoir rocks and structures, thus accumulating to form today’s oil and gas deposits.

Animal Wastes Become Oil

Turkey and pig slaughterhouse wastes are daily trucked into the world’s first biorefinery, a thermal conversion processing plant in Carthage, Missouri.1 On peak production days, 500 barrels of high-quality fuel oil better than crude oil are made from 270 tons of turkey guts and 20 tons of pig fat.

From the loading bay hopper, a pressurized pipe pushes the animal wastes into a brawny grinder that chews them into pea-size bits. A first-stage reactor breaks down the wastes with heat and pressure, until the pressure then rapidly drops in order to flash off the excess water and minerals. These are shunted off to dry into a high-calcium powdered fertilizer.

The remaining concentrated organic soup is poured into a second reaction tank, where it is heated to 500°F (260°C) and pressurized to 600 pounds per square inch (42 kilograms per square centimeter). Within 20 minutes the process replicates what happens to dead plants and animals buried deep in the earth’s sedimentary rock layers, chopping long, complex molecular chains of hydrogen and carbon into the short-chain molecules of oil. Next, the pressure and temperature are dropped, and the soup swirls through a centrifuge that separates any remaining water from the oil. That water, because slaughterhouse waste is laden with nitrogen and amino acids, is stored to be sold as a potent liquid fertilizer.

The oil produced can be blended with heavier fossil-fuel oils to upgrade them or simply used to power electrical utility generators. The good news is that it appears this thermal conversion technology can also be adapted to process sewage, old tires, and mixed plastics. And it is also energy efficient. Only 15 percent of the potential energy in the feedstock is used to power the operation, leaving 85 percent in the output of oil and fertilizer products.


  1. Lemley, B., “Anything into oil,” Discover 27 (4), 2006.

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  1. Gold, T. and Soter, S., The deep-earth gas hypothesis, Scientific American 242(6):154–161, 1980.
  2. Levorsen, A.I., Geology of Petroleum, 2nd ed., W.H. Freeman and Company, San Francisco, pp. 3–31, 1967.
  3. Tissot, B.P., and Welte, D.H., Petroleum Formation and Occurrence, 2nd ed., Springer-Verlag, Berlin, p. 128, 1984.
  4. McQueen, D.R., The chemistry of oil—explained by Flood geology, Impact #155, Institute for Creation Research, Santee, California, 1986.
  5. Russell, W.L., Principles of Petroleum Geology, 2nd ed., McGraw-Hill Book Company, New York, p. 25, 1960.
  6. Levorsen, p. 502.
  7. McQueen.
  8. Walker, K.R., et al., A model for carbonate to terrigenous clastic sequences; Geological Society of America Bulletin, 94, pp. 700–712, 1983.
  9. Tissot and Welte, p. 12.
  10. Ibid., p. 410.
  11. Di Nello, R.K., and Chang, C.K., Isolation and modification of natural porphyrins; in: Dolphin, D. (Ed.), The Porphyrins, Vol. 1: Structure and Synthesis, Part A, Academic Press, New York, p. 328, 1978.
  12. Marinelli, J., Power plants—the origin of fossil fuels; Plants & Gardens News 18(2), 2/pgn/2003su_fossilfuels.html, 2003.
  13. Tissot and Welte.
  14. Leslie, R.B., Evans, H.J., and Knight, C.L., Economic Geology of Australia and Papua New Guinea—3. Petroleum, Monograph No. 7, The Australasian Institute of Mining and Metallurgy, Melbourne, Australia, 1976.
  15. Snelling, A.A., The recent origin of Bass Strait Oil and Gas; Creation, 5(2), pp. 43–46, 1982; Brooks, J.D., and Smith, J.W., The diagenesis of plant lipids during the formation of coal, petroleum and natural gas—II. coalification and the formation of oil and gas in the Gippsland Basin; Geochimica et Cosmochimica Acta 33, pp. 1183–1194, 1969; and Shibaoka, M., Saxby, J.D., and Taylor, G.H., Hydrocarbon generation in Gippsland Basin, Australia—comparison with Cooper Basin, Australia; American Association of Petroleum Geologists Bulletin 62(7):1151–1158, 1978.
  16. Lemley, B., Anything into oil, Discover 27(4), 2006.
  17. Wise, K.P., The pre-Flood floating forest: a study in paleontological pattern recognition; in: Ivey, R.L., Jr. (Ed.), Proceedings of the Fifth International Conference on Creationism, Creation Science Fellowship, Pittsburgh, pp. 371–381, 2003.


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