Our society is powered by fossil fuels. Fossil fuels are all hydrocarbons formed from decaying organic matter under severe pressure. Whether the reserve of organic matter was compressed to form coal, oil, or natural gas depends on the geography of the area in which it is deposited. Oil and Natural Gas Oil and natural gas are deposits remaining from ancient seas. These minerals soak into the permeable rock layer, which later undergoes intense pressure as the earth's crust flexes and contracts.
Geologists perform land surveys to look for anticlime layers, which appear as folds in rock.
Once approximately two thirds of a reserve is exhausted, it is necessary to re-pressurize to bring the remaining third of oil or natural gas to the surface. This practice is often considered economically infeasible, and is only carried out if the oil prices are particularly high. Crude oil from wells is pumped via pipeline to a refinery, where a furnace is used to distill the oil. The different chemical formations of each kind of oil determines its usefulness. Branching hydrocarbons are called octanes, and are preferred for gasoline because they prevent knocking in the engine.