How oil is formed step by step?

Oil formation begins with the accumulation of organic matter, primarily from microscopic marine organisms, which settles on the ocean floor. Over millions of years, this organic material is buried under layers of sediment, where heat and pressure transform it into hydrocarbons through a process known as maturation. As the temperatures rise, the organic matter breaks down into kerogen, and eventually, with further heat and pressure, it converts into crude oil and natural gas. Finally, the oil migrates through porous rock layers until it is trapped by impermeable rock formations, creating reservoirs.