Your Petrol Was Once Ancient Sea Creatures? | How Crude Oil Actually Forms | NEXT IAS

Added: 2026-05-18

[00:00:00]Welcome to the science and tech series of next IAS. Did you know the petrol in your bike or car actually comes from tiny sea creatures that died millions of years ago? Sounds unbelievable, right?

[00:00:12]But that's exactly how crude oil is formed. Millions of years ago oceans were filled with microscopic plants and animals like planktons and algae. When they died, their remains settled deep under the sea floor. Over time, layers of mud and sand buried them completely.

[00:00:29]Since there was very little oxygen underground, the organic matter did not fully decay. Now imagine this material being trapped deep inside the earth for millions of years. As it went deeper, around 2 to 4 km below the surface, heat and pressure kept increasing. Slowly, this organic matter transformed into a waxy substance called kerogen.

[00:00:51]>> [music] >> Then, under the temperature between 65° C and 150° C, >> [music] >> the kerogen started breaking down into liquid and gaseous hydrocarbons. This is called the oil window, the perfect condition for crude oil formation. If the temperature becomes too high, [music] only natural gas forms.

[00:01:10]This widely acceptable explanation is known as the biogenic theory, which says crude oil comes from ancient living organism. There is also another idea that called the abiogenic theory, which claims oil formation deep inside earth without biological material. But scientists largely reject this theory.

[00:01:30]Not all crude oils are the same. Some oil contains less sulfur and is called sweet [music] crude, which is easier and cheaper to refine. Oil with more sulfur is called sour crude, and it needs extra processing. For example, Venezuela crude oil is usually heavier and more sour.

[00:01:47]So next time you fuel your vehicle, remember you are actually using energy created from life that existed millions of years before [music] human even appeared on Earth.