Petroleum
Petroleum, also known as crude oil or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons,[1] and is found in geological formations. The name petroleum covers both naturally occurring unprocessed crude oil and petroleum products that consist of refined crude oil.
"Crude oil" redirects here. For the 2008 film, see Crude Oil (film). For the fuel, see Petrol. For other uses, see Petroleum (disambiguation).
Petroleum is primarily recovered by oil drilling. Drilling is carried out after studies of structural geology, sedimentary basin analysis, and reservoir characterisation. Unconventional reserves such as oil sands and oil shale exist.
Once extracted, oil is refined and separated, most easily by distillation, into innumerable products for direct use or use in manufacturing. Products include fuels such as petrol (gasoline), diesel, kerosene and jet fuel; asphalt and lubricants; chemical reagents used to make plastics; solvents, textiles, refrigerants, paint, synthetic rubber, fertilizers, pesticides, pharmaceuticals, and thousands of others. Petroleum is used in manufacturing a vast variety of materials essential for modern life,[2] and it is estimated that the world consumes about 100 million barrels (16 million cubic metres) each day. Petroleum production can be extremely profitable and was critical to global economic development in the 20th century, with some countries, so-called "oil states", gaining significant economic and international power because of their control of oil production.
Petroleum exploitation can be damaging to the environment and human health. Extraction, refining and burning of petroleum fuels all release large quantities of greenhouse gases, so petroleum is one of the major contributors to climate change. Other negative environmental effects include direct releases, such as oil spills, and as well as air and water pollution at almost all stages of use. These environmental effects have direct and indirect health consequences for humans. Oil has also been a source of internal and inter-state conflict, leading to both state-led wars and other resource conflicts. Production of petroleum is estimated to reach peak oil before 2035[3] as global economies lower dependencies on petroleum as part of climate change mitigation and a transition towards renewable energy and electrification.[4] Oil has played a key role in industrialization and economic development.[5]
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, heavy if it has high density, or medium if it has a density between that of light and heavy.[81] Additionally, it may be referred to as sweet if it contains relatively little sulfur or sour if it contains substantial amounts of sulfur.[82]
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 revealed by the use of crude oil assay analysis in petroleum laboratories.[83]
Barrels from an area in which the crude oil's molecular characteristics have been determined and the oil has been classified are used as pricing references throughout the world. Some of the common reference crudes are:
There are declining amounts of these benchmark oils being produced each year, so other oils are more commonly what is actually delivered. While the reference price may be for West Texas Intermediate delivered at Cushing, the actual oil being traded may be a discounted Canadian heavy oil – Western Canadian Select – delivered at Hardisty, Alberta, and for a Brent Blend delivered at Shetland, it may be a discounted Russian Export Blend delivered at the port of Primorsk.[86]
Once extracted, oil is refined and separated, most easily by distillation, into numerous products for direct use or use in manufacturing, such as petrol (gasoline), diesel and kerosene to asphalt and chemical reagents (ethylene, propylene, butene, acrylic acid, para-xylene[87]) used to make plastics, pesticides and pharmaceuticals.[88]
Global fossil carbon emissions, an indicator of consumption, from 1800.TotalOil
![Rate of world energy usage per year from 1970.[119]](http://upload.wikimedia.org/wikipedia/commons/thumb/3/3a/World_energy_consumption.svg/160px-World_energy_consumption.svg.png)
Daily oil consumption from 1980 to 2006.
Oil consumption 1980 to 2007 by region.
Alternatives[edit]
In 2018 road transport used 49% of petroleum, aviation 8%, and uses other than energy 17%.[152] Electric vehicles are the main alternative for road transport and biojet for aviation.[153][154][155] Single-use plastics have a high carbon footprint and may pollute the sea, but as of 2022 the best alternatives are unclear.[156]
Hydrocarbons on other worlds[edit]
On Saturn's largest moon, Titan, lakes of liquid hydrocarbons comprising methane, ethane, propane and other constituents, occur naturally. Data collected by the space probe Cassini–Huygens yield an estimate that the visible lakes and seas of Titan contain about 300 times the volume of Earth's proven oil reserves.[193][194] Drilled samples from the surface of Mars taken in 2015 by the Curiosity rover's Mars Science Laboratory have found organic molecules of benzene and propane in 3-billion-year-old rock samples in Gale Crater.[195]