Petroleum

Petroleum (also called crude oil) is a naturally occurring liquid made up of a mixture of hydrocarbons—molecules composed of carbon and hydrogen. It accumulates in porous rocks deep underground, usually in layers covered by impermeable rock. It is extracted through drilled wells and then refined into various products including gasoline, diesel, kerosene, and gas.

Petroleum originated from ancient sea organisms, especially plankton, which accumulated over millions of years beneath layers of sediment. Heat and pressure converted organic matter into hydrocarbons. For this reason it is classified as a non-renewable energy source in the short term.

Production and exploration

Companies and government agencies use geological surveys and seismic measurement—a method in which sound waves are sent into the ground to detect how they return—to identify locations where petroleum might be found. After this, an exploratory well is drilled. If the quantity and quality are economically viable, large-scale production begins.

Refining and products

Crude oil cannot be used directly. It is sent to refineries, where it is separated through distillation—a process that separates components based on their boiling points. This produces gasoline for vehicles, diesel for heavy vehicles, kerosene for aircraft, and industrial oils for factories. Plastics, lubricants, and certain medicines are also derived from petroleum.

Economics and markets

The price of petroleum is measured in barrels and traded on global markets. Several countries have formed organizations to coordinate production levels, such as OPEC. Fluctuations in price directly affect the budgets of producing countries and fuel costs in consuming nations.

Environment

Burning petroleum products releases carbon dioxide, which contributes to climate change. Oil spills at sea cause damage to marine life. For this reason, many countries have implemented policies to shift toward alternative energy sources such as solar and wind power, although petroleum remains a major global energy source.