What is the origin of oil? it doesn’t come from dinosaurs – 05/26/2023 – Environment

Oil is one of the engines of today’s society, the reason for wars and one of the main factors responsible for climate change.

Every day, more than 80 million barrels of oil are extracted in the world. Its name comes from Latin and means “stone oil”.

The viscous liquid known as “black gold” is a mixture of hydrocarbons – compounds that contain in their molecular structure, mainly, carbon and hydrogen. It is the result of a transformation process that took place over millions of years.

But where does the oil come from? Most scientists defend a theory and guarantee that the origin of oil “is well understood”. But that doesn’t stop certain baseless beliefs from continuing to circulate…

THE MYTH OF DINOSAURS

It is estimated that about 70% of oil deposits were formed in the Mesozoic era, 66 to 252 million years ago.

The Mesozoic is divided into three periods: Triassic, Jurassic and Cretaceous. And it is also known as the era of reptiles, because it was the heyday of dinosaurs.

This fact may perhaps explain a misinformation that still circulates around the world.

“For some strange reason, the idea that oil comes from dinosaurs has remained with many people,” says geology professor Reidar Müller, from the University of Oslo, Norway, to the website sciencenorway.no. “But oil comes from trillions of tiny algae and plankton.”

No one knows for sure how this myth emerged, which circulated in different parts of the world. BBC News Mundo – the BBC’s Spanish-language news service – asked two Mexican experts if they were aware of this belief.

“Yes, it’s a misconception, but a very common one,” replied Professors Darío Solano and Iza Canales, from the Faculty of Engineering at the National Autonomous University of Mexico (Unam), Division of Earth Sciences.

“At least within our community, we can identify that many of the hydrocarbon-producing rocks are found in the layers of the Jurassic, which is a geological era that is usually associated with dinosaurs. Perhaps this relationship has contributed to reinforce the idea that this is its origin”, explains Solano.

“It is important that these myths are disproved, first of all to collaborate so that society, as a whole, eliminates the lack of knowledge about a substance of common and generalized use, in short, only by the general culture”, adds Canales. “And secondly, advancing understanding of where this resource comes from will make it possible to advance the development of new technologies or uses.”

HOW OIL IS FORMED

The protagonists of the story of the origin of oil are not the large reptiles, but the tiny beings.

The most accepted theory about the origin of petroleum is the so-called organic theory. According to her, the substance was generated by the decomposition of animal remains and microscopic algae accumulated at the bottom of seas and lakes.

This theory indicates that fine sediments and organic remains, mainly terrestrial or marine plants, are deposited in watercourses.

Certain processes cause the formation of kerogen, which is a mixture of these organic materials. And, after a long time, the pressure and temperature increase, finally forming hydrocarbon chains, according to UNAM scientists.

The accumulation of other geological layers over the deposits of organic matter generates pressure and temperature conditions that facilitate the action of anaerobic bacteria to slowly transform the organic matter into hydrocarbons with small amounts of other elements.

“In a simplified way, we can imagine our mixture of materials being cooked in a pressure cooker (that is, with certain pressure and temperature conditions) for a long time, until the original matter is decomposed into chains of carbon and hydrogen. , the process is similar”, explain the Mexican specialists. “Next, the material needs to migrate from the rocks where it was cooked to the rocks that will store it.”

This theory is one of the most accepted, since all oil deposits were found in sedimentary land and, along with them, there were fossil remains of animals and plants.

WHERE DOES OIL ENERGY COME FROM?

Petroleum can also come from the transformation of organic material from ancient forests.

It is understood in the organic theory that any type of organic material can be present. In fact, the type of hydrocarbon obtained from kerogens rich in terrestrial plant matter is associated with gas deposits, according to the Mexican scientists.

And here comes another myth to be clarified. Would oil energy be solar energy captured by the photosynthesis of phytoplankton (vegetable organisms) and transferred to zooplankton (animal organisms)?

“No, this is a misconception,” says Canales. “The energy we get from oil today comes from the oxidation [combustão] chains of hydrogen and carbon [hidrocarbonetos].”

“It is true that energy and matter are interchangeable, but posing the question in this way sounds as if phytoplankton and zooplankton were solar batteries”, explains Solano.

He continues: “One can think of it as something analogous to how we humans can eat a lot of things and the body turns the food, breaking it down in our digestive system through another oxidation process (digestion), and takes advantage of these simplest components at the cellular level.”

ALTERNATIVE THEORIES

Scientists defended in the past that oil would have an inorganic origin and form in the depths of the Earth, without the need for the remains of living organisms.

Several of these theories were already presented in the 19th century. One of their defenders was the Russian chemist Dmitri Mendeleev (1834-1907), who published the first periodic table of elements.

Inorganic theories state that, within the Earth’s mantle, carbon can exist in the form of hydrocarbon molecules, mainly methane, and a large amount of the hydrocarbons found in petroleum can be generated through processes that do not require organic fossils.

These hydrocarbons can leave the mantle for the Earth’s crust, until they escape to the surface or remain in impermeable layers, forming oil deposits.

One version of these theories is that of the Austrian astrophysicist Thomas Gold (1920-2004), who was professor of astronomy at Cornell University, in the United States. Gold published a study in 1992 in the journal of the Academy of Sciences of the United States (PNAS), which was later expanded to form a book with the same title – The Deep and Warm Biosphere, in the Portuguese edition.

For him, Earth’s hydrocarbons are not the by-product of biological waste (“fossil fuels”), but rather a common component of the materials that formed the Earth some 4.5 billion years ago.

Gold recognized that the same hypothesis had already been defended in the 1950s by Soviet scientists. But the theory of the inorganic origin of petroleum is not accepted by most scholars.

“We dare to speak for our colleagues in academia and science to say that the theories of inorganic origin have not been successfully proven and that it has not been possible to generate hydrocarbons in the laboratory in this way”, emphasize the experts from the National University of Mexico.

ONE LAST QUESTION

Since the organic theory of the origin of petroleum is the most accepted, one question may still be unanswered.

If the dinosaurs lived at the same time as the formation of oil, in the Mesozoic, it may have happened that their remains – the organic matter of a dinosaur – fell to the bottom of the sea or lakes and underwent a process of compression and transformation into oil.

“Technically, we could say that any organic matter can be present in the generation of oil”, affirm Darío Solano and Iza Canales.

“But it is important to mention that the generation of oil is a very delicate process. Very large volumes of matter are needed, which could only be achieved by the large amounts of plankton in the sea. Therefore, volumes from other sources are not so significant” , conclude the Mexican experts.

This text was originally published here.