Oil, also known as petroleum or crude oil, is formed from the remains of ancient marine organisms. Over millions of years, these organisms—microscopic plants and animals—died and sank to the ocean floor.
The Formation Process: From Organisms to Oil
- Accumulation of Organic Matter: The remains of these marine organisms accumulated in thick layers on the seabed, often in oxygen-poor environments that slowed decomposition.
- Sediment Burial: These layers were then covered by subsequent layers of sand, silt, and other sediments. The weight of these overlying layers created immense pressure.
- Transformation Under Heat and Pressure: The combination of heat and pressure from deep burial transformed the organic matter over millions of years. This process converted the organic remains into hydrocarbons – the basic components of crude oil.
- Migration and Accumulation: The newly formed oil, being less dense than the surrounding rock, migrated upwards through porous rock layers until it became trapped beneath impermeable layers, such as shale or salt domes, forming underground reservoirs.
Types of Organisms Involved
The primary contributors to oil formation were microscopic marine organisms such as:
- Diatoms (single-celled algae)
- Phytoplankton (microscopic plants)
- Zooplankton (microscopic animals)
These organisms, although tiny individually, accumulated in massive quantities over geological time, providing the raw material for oil formation. The reference material emphasizes that "Over millions of years, the remains of these animals and plants were covered by layers of sand, silt, and rock. Heat and pressure from these layers turned the remains into what we now call crude oil or petroleum."
The process is complex and takes millions of years, making oil a non-renewable resource.
