Petroleum

For other uses, see Petroleum (disambiguation).

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Pumpjack pumping an oil well near Lubbock, Texas.

Petroleum (L. petroleum, from Greek: petra (rock) + Latin: oleum (oil)^[1]) or crude oil is a naturally occurring, flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights and other liquid organic compounds, that are found in geologic formations beneath the Earth's surface.Petroleum is recovered mostly through oil drilling. This latter stage comes after the studies of structural geology (at the reservoir scale), sedimentary basin analysis, reservoir characterization (mainly in terms of porosity and permeable structures)It is refined and separated, most easily by boiling point, into a large number of consumer products, from gasoline and kerosene to asphalt and chemical reagents used to make plastics and pharmaceuticals.^[4] Petroleum is used in manufacturing a wide variety of materials.^[4]
The term petroleum was found (in the spelling "petraoleum") in tenth-century Old English sources.^[5] It was used in the treatise De Natura Fossilium, published in 1546 by the German mineralogist Georg Bauer, also known as Georgius Agricola.^[6] In the 19th Century, the term petroleum was frequently used to refer to mineral oils produced by distillation from mined organic solids such as cannel coal (and later oil shale), and refined oils produced from them; in the United Kingdom, storage (and later transport) of these oils were regulated by a series of Petroleum Acts, from the Petroleum Act 1862 c. 66 onward.

Petroleum by country

Petroleum by country

Consumption statistics

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  Global fossil carbon emissions, an indicator of consumption, for 1800–2007. Total is black, Oil is in blue.
  
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  EIA Primary Energy Outlook (retrieved on 2011-06)
  
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  daily oil consumption from 1980 to 2006
  
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  oil consumption by percentage of total per region from 1980 to 2006: red=USA, blue=Europe, yellow=Asia+Oceania
  

] Consumption

History

History

Main article: History of petroleum

Oil derrick in Okemah, Oklahoma, 1922.

Petroleum, in one form or another, has been used since ancient times, and is now important across society, including in economy, politics and technology. The rise in importance was mostly due to the invention of the internal combustion engine, the rise in commercial aviation and the increasing use of plastic.
More than 4000 years ago, according to Herodotus and Diodorus Siculus, asphalt was used in the construction of the walls and towers of Babylon; there were oil pits near Ardericca (near Babylon), and a pitch spring on Zacynthus.^[30] Great quantities of it were found on the banks of the river Issus, one of the tributaries of the Euphrates. Ancient Persian tablets indicate the medicinal and lighting uses of petroleum in the upper levels of their society. By 347 CE, oil was produced from bamboo-drilled wells in China.^[31]
In the 1850s, the process to distill kerosene from petroleum was invented by Ignacy Łukasiewicz, providing a cheaper alternative to whale oil. The demand for the petroleum as a fuel for lighting in North America and around the world quickly grew.^[32] The world's first commercial oil well was drilled in Poland in 1853. Oil exploration developed in many parts of the world with the Russian Empire, particularly the Branobel company in Azerbaijan (Asia's first modern borehole oil production began in 1848 at the Bibi-Heybat field near Baku), taking the lead in production by the end of the 19th century.^{[33][verification needed]}

Petroleum industry

Petroleum industry

New York Mercantile Exchange prices for West Texas Intermediate 1996–2009

Main article: Petroleum industry

The petroleum industry is involved in the global processes of exploration, extraction, refining, transporting (often with oil tankers and pipelines), and marketing petroleum products. The largest volume products of the industry are fuel oil and petrol . Petroleum is also the raw material for many chemical products, including pharmaceuticals, solvents, fertilizers, pesticides, and plastics. The industry is usually divided into three major components: upstream, midstream and downstream. Midstream operations are usually included in the downstream category.
Petroleum is vital to many industries, and is of importance to the maintenance of industrialized civilization itself, and thus is critical concern to many nations. Oil accounts for a large percentage of the world's energy consumption, ranging from a low of 32% for Europe and Asia, up to a high of 53% for the Middle East. Other geographic regions' consumption patterns are as follows: South and Central America (44%), Africa (41%), and North America (40%). The world at large consumes 30 billion barrels (4.8 km³) of oil per year, and the top oil consumers largely consist of developed nations. In fact, 24% of the oil consumed in 2004 went to the United States alone,^[27] though by 2007 this had dropped to 21% of world oil consumed.^[28]

Classification

Classification

See also: Benchmark (crude oil)

A sample of medium heavy crude oil

The petroleum industry generally classifies crude oil by the geographic location it is produced in (e.g. West Texas Intermediate, Brent, or Oman), its API gravity (an oil industry measure of density), and its sulfur content. Crude oil may be considered light if it has low density or heavy if it has high density; and it may be referred to as sweet if it contains relatively little sulfur or sour if it contains substantial amounts of sulfur.
The geographic location is important because it affects transportation costs to the refinery. Light crude oil is more desirable than heavy oil since it produces a higher yield of gasoline, while sweet oil commands a higher price than sour oil because it has fewer environmental problems and requires less refining to meet sulfur standards imposed on fuels in consuming countries. Each crude oil has unique molecular characteristics which are understood by the use of crude oil assay analysis in petroleum laboratories.

Crude oil

Crude oil

Crude oil reservoirs

Hydrocarbon trap.

Three conditions must be present for oil reservoirs to form: a source rock rich in hydrocarbon material buried deep enough for subterranean heat to cook it into oil; a porous and permeable reservoir rock for it to accumulate in; and a cap rock (seal) or other mechanism that prevents it from escaping to the surface. Within these reservoirs, fluids will typically organize themselves like a three-layer cake with a layer of water below the oil layer and a layer of gas above it, although the different layers vary in size between reservoirs. Because most hydrocarbons are lighter than rock or water, they often migrate upward through adjacent rock layers until either reaching the surface or becoming trapped within porous rocks (known as reservoirs) by impermeable rocks above. However, the process is influenced by underground water flows, causing oil to migrate hundreds of kilometres horizontally or even short distances downward before becoming trapped in a reservoir. When hydrocarbons are concentrated in a trap, an oil field forms, from which the liquid can be extracted by drilling and pumping.
The reactions that produce oil and natural gas are often modeled as first order breakdown reactions, where hydrocarbons are broken down to oil and natural gas by a set of parallel reactions, and oil eventually breaks down to natural gas by another set of reactions. The latter set is regularly used in petrochemical plants and oil refineries.