How petroleum forms

Petroleum is a naturally occurring mineral which consists of organic compounds called hydrocarbons.

It is found in liquid, gas and even solid forms. The term hydrocarbon refers to the two main elements in petroleum – hydrogen atoms joined to a carbon atom.

Petroleum originates from plants or marine microorganisms, like algae and plankton which lived hundreds of millions of years ago. If trapped and buried in sedimentary rock, over time a combination of the heat and pressure below the earth surface sees this organic matter transformed into oil, or in hotter conditions, natural gas.

The resulting oil and/or gas then moves through holes rock until it is either trapped in a reservoir, or reaches the surface. Drilling a well into these reservoirs allows any oil and gas to be extracted.

Petroleum  300 Million years
300 Million years

Small marine organisms and plants die and are buried under layers of sedimentary rock.
Petroleum 100 Million years
100 Million years

Immense heat and pressure transform the organic material into oil and gas over millions of years.
Petroleum today

Operators drill through the rock and sediment to discover viable petroleum accumulations.
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