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Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black
liquid A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter (the others being solid, gas, a ...
mixture of mainly
hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ex ...
s, and is found in
geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...
s. The name ''petroleum'' covers both naturally occurring unprocessed crude oil and
petroleum product Petroleum products are materials derived from crude oil (petroleum) as it is processed in oil refineries. Unlike petrochemicals, which are a collection of well-defined usually pure organic compounds, petroleum products are complex mixtures. The m ...
s that consist of refined crude oil. A
fossil fuel A fossil fuel is a hydrocarbon-containing material formed naturally in the Earth's crust from the remains of dead plants and animals that is extracted and burned as a fuel. The main fossil fuels are coal, oil, and natural gas. Fossil fuels m ...
, petroleum is formed when large quantities of dead organisms, mostly
zooplankton Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...
and
algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...
, are buried underneath
sedimentary rock Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles ...
and subjected to both prolonged heat and pressure. Petroleum is primarily recovered by
oil drilling An oil well is a drillhole boring in Earth that is designed to bring petroleum oil hydrocarbons to the surface. Usually some natural gas is released as associated petroleum gas along with the oil. A well that is designed to produce only gas may ...
. Drilling is carried out after studies of structural geology, sedimentary basin analysis, and reservoir characterisation. Recent developments in technologies have also led to exploitation of other unconventional reserves such as
oil sands Oil sands, tar sands, crude bitumen, or bituminous sands, are a type of unconventional petroleum deposit. Oil sands are either loose sands or partially consolidated sandstone containing a naturally occurring mixture of sand, clay, and wate ...
and
oil shale Oil shale is an organic-rich fine-grained sedimentary rock containing kerogen (a solid mixture of organic chemical compounds) from which liquid hydrocarbons can be produced. In addition to kerogen, general composition of oil shales constitute ...
. Once extracted, oil is refined and separated, most easily by
distillation Distillation, or classical distillation, is the process of separation process, separating the components or substances from a liquid mixture by using selective boiling and condensation, usually inside an apparatus known as a still. Dry distilla ...
, into innumerable products for direct use or use in manufacturing. Products include fuels such as
gasoline Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic co ...
(petrol),
diesel Diesel may refer to: * Diesel engine, an internal combustion engine where ignition is caused by compression * Diesel fuel, a liquid fuel used in diesel engines * Diesel locomotive, a railway locomotive in which the prime mover is a diesel engin ...
,
kerosene Kerosene, paraffin, or lamp oil is a combustible hydrocarbon liquid which is derived from petroleum. It is widely used as a fuel in aviation as well as households. Its name derives from el, κηρός (''keros'') meaning "wax", and was regi ...
and
jet fuel Jet fuel or aviation turbine fuel (ATF, also abbreviated avtur) is a type of aviation fuel designed for use in aircraft powered by gas-turbine engines. It is colorless to straw-colored in appearance. The most commonly used fuels for commercial a ...
among many others;
asphalt Asphalt, also known as bitumen (, ), is a sticky, black, highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term a ...
and
lubricants A lubricant (sometimes shortened to lube) is a substance that helps to reduce friction between surfaces in mutual contact, which ultimately reduces the heat generated when the surfaces move. It may also have the function of transmitting forces, t ...
; chemical
reagent In chemistry, a reagent ( ) or analytical reagent is a substance or compound added to a system to cause a chemical reaction, or test if one occurs. The terms ''reactant'' and ''reagent'' are often used interchangeably, but reactant specifies a ...
s used to make
plastic Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptab ...
s;
solvents A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for p ...
,
textiles Textile is an umbrella term that includes various fiber-based materials, including fibers, yarns, filaments, threads, different fabric types, etc. At first, the word "textiles" only referred to woven fabrics. However, weaving is not the ...
,
refrigerants A refrigerant is a working fluid used in the refrigeration cycle of air conditioning systems and heat pumps where in most cases they undergo a repeated phase transition from a liquid to a gas and back again. Refrigerants are heavily regulated due ...
,
paint Paint is any pigmented liquid, liquefiable, or solid mastic composition that, after application to a substrate in a thin layer, converts to a solid film. It is most commonly used to protect, color, or provide texture. Paint can be made in many ...
,
synthetic rubber A synthetic rubber is an artificial elastomer. They are polymers synthesized from petroleum byproducts. About 32-million metric tons of rubbers are produced annually in the United States, and of that amount two thirds are synthetic. Synthetic rubbe ...
,
fertilizers A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from ...
,
pesticide Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and lampri ...
s,
pharmaceuticals A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy (pharmacotherapy) is an important part of the medical field and rel ...
, and thousands of others. Petroleum is used in manufacturing a vast variety of materials essential for modern life, and it is estimated that the world consumes about 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 A petrostate or oil state is a nation whose economy is heavily dependent on the extraction and export of oil or natural gas. The presence alone of large oil and gas industries does not define a petrostate; countries like Norway, Canada, and the Uni ...
", gaining significant economic and international power because of their control of oil production. Petroleum exploitation and use has had significant negative environmental and social consequences. Extraction,
refining {{Unreferenced, date=December 2009 Refining (also perhaps called by the mathematical term affining) is the process of purification of a (1) substance or a (2) form. The term is usually used of a natural resource that is almost in a usable form, b ...
and
burning Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combusti ...
of petroleum fuels all release large quantities of
greenhouse gas A greenhouse gas (GHG or GhG) is a gas that Absorption (electromagnetic radiation), absorbs and Emission (electromagnetic radiation), emits radiant energy within the thermal infrared range, causing the greenhouse effect. The primary greenhouse ...
es, so petroleum is one of the major contributors to climate change. Other negative environmental effects include
oil spill An oil spill is the release of a liquid petroleum hydrocarbon into the environment, especially the marine ecosystem, due to human activity, and is a form of pollution. The term is usually given to marine oil spills, where oil is released into th ...
s, and air and water pollution. Some of these effects have direct and indirect health consequences for humans. Oil has also been a source of conflict leading to both state-led-wars and other conflicts. Production of petroleum is speculated to reach
peak oil Peak oil is the hypothetical point in time when the maximum rate of global oil production is reached, after which it is argued that production will begin an irreversible decline. It is related to the distinct concept of oil depletion; while ...
before 2035 as global economies lower dependencies on petroleum as part of
climate change mitigation Climate change mitigation is action to limit climate change by reducing Greenhouse gas emissions, emissions of greenhouse gases or Carbon sink, removing those gases from the atmosphere. The recent rise in global average temperature is mostly caus ...
and a transition towards
renewable energy Renewable energy is energy that is collected from renewable resources that are naturally replenished on a human timescale. It includes sources such as sunlight, wind, the movement of water, and geothermal heat. Although most renewable energy ...
and
electrification Electrification is the process of powering by electricity and, in many contexts, the introduction of such power by changing over from an earlier power source. The broad meaning of the term, such as in the history of technology, economic histor ...
.


Etymology

The word ''petroleum'' comes from Medieval Latin (literally 'rock oil'), which comes from Latin
petra Petra ( ar, ٱلْبَتْرَاء, Al-Batrāʾ; grc, Πέτρα, "Rock", Nabataean Aramaic, Nabataean: ), originally known to its inhabitants as Raqmu or Raqēmō, is an historic and archaeological city in southern Jordan. It is adjacent to t ...
'rock' (from Greek ) and
oleum Oleum (Latin ''oleum'', meaning oil), or fuming sulfuric acid, is a term referring to solutions of various compositions of sulfur trioxide in sulfuric acid, or sometimes more specifically to disulfuric acid (also known as pyrosulfuric acid). Ole ...
'oil' (from Greek ). The term was used in the treatise ''
De Natura Fossilium ''De Natura Fossilium'' is a scientific text written by Georg Bauer also known as Georgius Agricola, first published in 1546. The book represents the first scientific attempt to categorize minerals, rocks and sediments since the publication of Pl ...
'', published in 1546 by the German mineralogist
Georg Bauer Georgius Agricola (; born Georg Pawer or Georg Bauer; 24 March 1494 – 21 November 1555) was a German Humanist scholar, mineralogist and metallurgist. Born in the small town of Glauchau, in the Electorate of Saxony of the Holy Roman Empire ...
, also known as Georgius Agricola. In the 19th century, the term ''petroleum'' was often used to refer to
mineral oil Mineral oil is any of various colorless, odorless, light mixtures of higher alkanes from a mineral source, particularly a distillate of petroleum, as distinct from usually edible vegetable oils. The name 'mineral oil' by itself is imprecise, ...
s produced by distillation from mined organic solids such as cannel coal (and later
oil shale Oil shale is an organic-rich fine-grained sedimentary rock containing kerogen (a solid mixture of organic chemical compounds) from which liquid hydrocarbons can be produced. In addition to kerogen, general composition of oil shales constitute ...
) 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 1863'' onwards.


History


Early

Petroleum, in one form or another, has been used since ancient times. More than 4300 years ago,
bitumen Asphalt, also known as bitumen (, ), is a sticky, black, highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term a ...
was mentioned when the Sumerians used it to make boats. Tablet of the legend of the birth of
Sargon of Akkad Sargon of Akkad (; akk, ''Šarrugi''), also known as Sargon the Great, was the first ruler of the Akkadian Empire, known for his conquests of the Sumerian city-states in the 24th to 23rd centuries BC.The date of the reign of Sargon is highl ...
, mentioned a basket which was closed by straw and bitumen. More than 4000 years ago, according to
Herodotus Herodotus ( ; grc, , }; BC) was an ancient Greek historian and geographer from the Greek city of Halicarnassus, part of the Persian Empire (now Bodrum, Turkey) and a later citizen of Thurii in modern Calabria ( Italy). He is known f ...
and
Diodorus Siculus Diodorus Siculus, or Diodorus of Sicily ( grc-gre, Διόδωρος ;  1st century BC), was an ancient Greek historian. He is known for writing the monumental universal history ''Bibliotheca historica'', in forty books, fifteen of which su ...
,
asphalt Asphalt, also known as bitumen (, ), is a sticky, black, highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term a ...
was used in the construction of the walls and towers of
Babylon ''Bābili(m)'' * sux, 𒆍𒀭𒊏𒆠 * arc, 𐡁𐡁𐡋 ''Bāḇel'' * syc, ܒܒܠ ''Bāḇel'' * grc-gre, Βαβυλών ''Babylṓn'' * he, בָּבֶל ''Bāvel'' * peo, 𐎲𐎠𐎲𐎡𐎽𐎢 ''Bābiru'' * elx, 𒀸𒁀𒉿𒇷 ''Babi ...
; there were oil pits near Ardericca (near Babylon), and a pitch spring on
Zacynthus Zakynthos (also spelled Zakinthos; el, Ζάκυνθος, Zákynthos ; it, Zacinto ) or Zante (, , ; el, Τζάντε, Tzánte ; from the Venetian form) is a Greek island in the Ionian Sea. It is the third largest of the Ionian Islands. Za ...
. Great quantities of it were found on the banks of the river Issus, one of the tributaries of the
Euphrates The Euphrates () is the longest and one of the most historically important rivers of Western Asia. Tigris–Euphrates river system, Together with the Tigris, it is one of the two defining rivers of Mesopotamia ( ''the land between the rivers'') ...
. Ancient
Persian Persian may refer to: * People and things from Iran, historically called ''Persia'' in the English language ** Persians, the majority ethnic group in Iran, not to be conflated with the Iranic peoples ** Persian language, an Iranian language of the ...
tablets indicate the medicinal and lighting uses of petroleum in the upper levels of their society. The use of petroleum in ancient China dates back to more than 2000 years ago. The ''
I Ching The ''I Ching'' or ''Yi Jing'' (, ), usually translated ''Book of Changes'' or ''Classic of Changes'', is an ancient Chinese divination text that is among the oldest of the Chinese classics. Originally a divination manual in the Western Zho ...
'', one of the earliest Chinese writings, cites that oil in its raw state, without refining, was first discovered, extracted, and used in China in the first century BCE. In addition, the Chinese were the first to record the use of petroleum as fuel as early as the fourth century BCE. By 347 CE, oil was produced from bamboo-drilled wells in China.
Crude oil Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crude ...
was often distilled by Persian chemists, with clear descriptions given in Arabic handbooks such as those of
Muhammad ibn Zakarīya Rāzi Abū Bakr al-Rāzī (full name: ar, أبو بکر محمد بن زکریاء الرازي, translit=Abū Bakr Muḥammad ibn Zakariyyāʾ al-Rāzī, label=none), () rather than ar, زکریاء, label=none (), as for example in , or in . In m ...
(Rhazes). The streets of
Baghdad Baghdad (; ar, بَغْدَاد , ) is the capital of Iraq and the second-largest city in the Arab world after Cairo. It is located on the Tigris near the ruins of the ancient city of Babylon and the Sassanid Persian capital of Ctesiphon ...
were paved with
tar Tar is a dark brown or black viscous liquid of hydrocarbons and free carbon, obtained from a wide variety of organic materials through destructive distillation. Tar can be produced from coal, wood, petroleum, or peat. "a dark brown or black bit ...
, derived from petroleum that became accessible from natural fields in the region. In the 9th century,
oil field A petroleum reservoir or oil and gas reservoir is a subsurface accumulation of hydrocarbons contained in porous or fractured rock formations. Such reservoirs form when kerogen (ancient plant matter) is created in surrounding rock by the presence ...
s were exploited in the area around modern
Baku Baku (, ; az, Bakı ) is the capital and largest city of Azerbaijan, as well as the largest city on the Caspian Sea and of the Caucasus region. Baku is located below sea level, which makes it the lowest lying national capital in the world a ...
,
Azerbaijan Azerbaijan (, ; az, Azərbaycan ), officially the Republic of Azerbaijan, , also sometimes officially called the Azerbaijan Republic is a transcontinental country located at the boundary of Eastern Europe and Western Asia. It is a part of th ...
. These fields were described by the
Arab geographer Medieval Islamic geography and cartography refer to the study of geography and cartography in the Muslim world during the Islamic Golden Age (variously dated between the 8th century and 16th century). Muslim scholars made advances to the map-maki ...
Abu al-Hasan 'Alī al-Mas'ūdī Al-Mas'udi ( ar, أَبُو ٱلْحَسَن عَلِيّ ٱبْن ٱلْحُسَيْن ٱبْن عَلِيّ ٱلْمَسْعُودِيّ, '; –956) was an Arab historian, geographer and traveler. He is sometimes referred to as the "Herodotus ...
in the 10th century, and by
Marco Polo Marco Polo (, , ; 8 January 1324) was a Venetian merchant, explorer and writer who travelled through Asia along the Silk Road between 1271 and 1295. His travels are recorded in ''The Travels of Marco Polo'' (also known as ''Book of the Marv ...
in the 13th century, who described the output of those wells as hundreds of shiploads. Arab and Persian chemists also distilled crude oil in order to produce
flammable A combustible material is something that can burn (i.e., ''combust'') in air. A combustible material is flammable if it ignites easily at ambient temperatures. In other words, a combustible material ignites with some effort and a flammable mat ...
products for military purposes. Through
Islamic Spain Al-Andalus translit. ; an, al-Andalus; ast, al-Ándalus; eu, al-Andalus; ber, ⴰⵏⴷⴰⵍⵓⵙ, label= Berber, translit=Andalus; ca, al-Àndalus; gl, al-Andalus; oc, Al Andalús; pt, al-Ândalus; es, al-Ándalus () was the Mu ...
, distillation became available in
Western Europe Western Europe is the western region of Europe. The region's countries and territories vary depending on context. The concept of "the West" appeared in Europe in juxtaposition to "the East" and originally applied to the ancient Mediterranean ...
by the 12th century. It has also been present in Romania since the 13th century, being recorded as păcură. Sophisticated oil pits, deep, were dug by the
Seneca People The Seneca () ( see, Onödowáʼga:, "Great Hill People") are a group of indigenous peoples of the Americas, Indigenous Iroquoian-speaking people who historically lived south of Lake Ontario, one of the five Great Lakes in North America. Their n ...
and other
Iroquois The Iroquois ( or ), officially the Haudenosaunee ( meaning "people of the longhouse"), are an Iroquoian-speaking confederacy of First Nations peoples in northeast North America/ Turtle Island. They were known during the colonial years to ...
in
Western Pennsylvania Western Pennsylvania is a region in the U.S. state of Pennsylvania, covering the western third of the state. Pittsburgh is the region's principal city, with a metropolitan area population of about 2.4 million people, and serves as its economic ...
as early as 1415–1450. The French General Louis-Joseph de Montcalm encountered Seneca using petroleum for ceremonial fires and as a healing lotion during a visit to Fort Duquesne in 1750. Early British explorers to
Myanmar Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John C. Wells, Joh ...
documented a flourishing oil extraction industry based in
Yenangyaung Yenangyaung ( my, ရေနံချောင်း; literally "stream of oil") is a city in the Magway Region of central Myanmar, located on the Irrawaddy River and 363 miles from Yangon. Until 1974, it remained the capital city of both Minbu Div ...
that, in 1795, had hundreds of hand-dug wells under production.
Pechelbronn Merkwiller-Pechelbronn () is a commune in the Bas-Rhin department in Grand Est in north-eastern France. It is notable as the original home of oil sands mining. Oil sands were mined from 1745 in Merkwiller-Pechelbronn, initially under the directi ...
(Pitch fountain) is said to be the first European site where petroleum has been explored and used. The still active Erdpechquelle, a spring where petroleum appears mixed with water has been used since 1498, notably for medical purposes. Oil sands have been mined since the 18th century. In
Wietze Wietze is a municipality in the district of Celle, in Lower Saxony, Germany. It is situated at the confluence of the river Aller and its tributary Wietze, approx. 15 km west of Celle. It is the site of the German Oil Museum The German O ...
in lower Saxony, natural asphalt/bitumen has been explored since the 18th century. Both in Pechelbronn as in Wietze, the coal industry dominated the petroleum technologies.


Modern

Chemist James Young noticed a natural petroleum seepage in the
Riddings Riddings is a large village in Derbyshire, England. The appropriate ward of the Amber Valley Council is called Ironville and Riddings. The population of this ward as at the 2011 census was 5,821. It is located south of Alfreton near the hamlet o ...
colliery Coal mining is the process of extracting coal from the ground. Coal is valued for its energy content and since the 1880s has been widely used to generate electricity. Steel and cement industries use coal as a fuel for extraction of iron from ...
at
Alfreton Alfreton ( ) is a town and civil parish in the Amber Valley district of Derbyshire, England. The town was formerly a Norman Manor and later an Urban District. The population of the Alfreton parish was 7,971 at the 2011 Census. The villages of Ir ...
,
Derbyshire Derbyshire ( ) is a ceremonial county in the East Midlands, England. It includes much of the Peak District National Park, the southern end of the Pennine range of hills and part of the National Forest. It borders Greater Manchester to the nor ...
from which he distilled a light thin oil suitable for use as lamp oil, at the same time obtaining a more viscous oil suitable for lubricating machinery. In 1848, Young set up a small business refining the crude oil. Young eventually succeeded, by distilling cannel coal at a low heat, in creating a fluid resembling petroleum, which when treated in the same way as the seep oil gave similar products. Young found that by slow distillation he could obtain a number of useful liquids from it, one of which he named "paraffine oil" because at low temperatures it congealed into a substance resembling paraffin wax. The production of these oils and solid
paraffin wax Paraffin wax (or petroleum wax) is a soft colorless solid derived from petroleum, coal, or oil shale that consists of a mixture of hydrocarbon molecules containing between 20 and 40 carbon atoms. It is solid at room temperature and begins to m ...
from coal formed the subject of his patent dated 17 October 1850. In 1850 Young & Meldrum and Edward William Binney entered into partnership under the title of E.W. Binney & Co. at
Bathgate Bathgate ( sco, Bathket or , gd, Both Chèit) is a town in West Lothian, Scotland, west of Livingston, Scotland, Livingston and adjacent to the M8 motorway (Scotland), M8 motorway. Nearby towns are Armadale, West Lothian, Armadale, Blackburn, ...
in
West Lothian West Lothian ( sco, Wast Lowden; gd, Lodainn an Iar) is one of the 32 council areas of Scotland, and was one of its shires of Scotland, historic counties. The county was called Linlithgowshire until 1925. The historic county was bounded geogra ...
and E. Meldrum & Co. at Glasgow; their works at Bathgate were completed in 1851 and became the first truly commercial oil-works in the world with the first modern oil refinery. The world's first oil refinery was built in 1856 by
Ignacy Łukasiewicz Jan Józef Ignacy Łukasiewicz (; 8 March 1822 – 7 January 1882) was a Polish pharmacist, engineer, businessman, inventor, and philanthropist. He was one of the most prominent philanthropists in the Kingdom of Galicia and Lodomeria, crown land o ...
. His achievements also included the discovery of how to distill kerosene from seep oil, the invention of the modern kerosene lamp (1853), the introduction of the first modern street lamp in Europe (1853), and the construction of the world's first modern oil well (1854). The demand for petroleum as a fuel for lighting in North America and around the world quickly grew.
Edwin Drake Edwin Laurentine Drake (March 29, 1819 – November 9, 1880), also known as Colonel Drake, was an American businessman and the first American to successfully drill for oil. Early life Edwin Drake was born in Greenville, New York on March 2 ...
's 1859 well near Titusville, Pennsylvania, is popularly considered the first modern well. Already 1858 Georg Christian Konrad Hunäus had found a significant amount of petroleum while drilling for
lignite Lignite, often referred to as brown coal, is a soft, brown, combustible, sedimentary rock formed from naturally compressed peat. It has a carbon content around 25–35%, and is considered the lowest rank of coal due to its relatively low heat ...
1858 in
Wietze Wietze is a municipality in the district of Celle, in Lower Saxony, Germany. It is situated at the confluence of the river Aller and its tributary Wietze, approx. 15 km west of Celle. It is the site of the German Oil Museum The German O ...
, Germany. Wietze later provided about 80% of the German consumption in the Wilhelminian Era. The production stopped in 1963, but Wietze has hosted a Petroleum Museum since 1970. Drake's well is probably singled out because it was drilled, not dug; because it used a steam engine; because there was a company associated with it; and because it touched off a major boom. However, there was considerable activity before Drake in various parts of the world in the mid-19th century. A group directed by Major Alexeyev of the Bakinskii Corps of Mining Engineers hand-drilled a well in the Baku region of Bibi-Heybat in 1846. There were engine-drilled wells in West Virginia in the same year as Drake's well. An early commercial well was hand dug in
Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populous ...
in 1853, and another in nearby
Romania Romania ( ; ro, România ) is a country located at the crossroads of Central Europe, Central, Eastern Europe, Eastern, and Southeast Europe, Southeastern Europe. It borders Bulgaria to the south, Ukraine to the north, Hungary to the west, S ...
in 1857. At around the same time the world's first, small, oil refinery was opened at
Jasło Jasło is a county town in south-eastern Poland with 36,641 inhabitants, as of 31 December 2012. It is situated in the Subcarpathian Voivodeship (since 1999), and it was previously part of Krosno Voivodeship (1975–1998). It is located in Lesse ...
in Poland, with a larger one opened at
Ploiești Ploiești ( , , ), formerly spelled Ploești, is a city and county seat in Prahova County, Romania. Part of the historical region of Muntenia, it is located north of Bucharest. The area of Ploiești is around , and it borders the Blejoi commu ...
in Romania shortly after. Romania is the first country in the world to have had its annual crude oil output officially recorded in international statistics: 275 tonnes for 1857. The first commercial oil well in Canada became operational in 1858 at
Oil Springs, Ontario Oil Springs is a village in Lambton County, Ontario, Canada, located along Former Provincial Highway 21 south of Oil City. The village, an enclave within Enniskillen Township, is the site of North America's first commercial oil well. It is home ...
(then
Canada West The Province of Canada (or the United Province of Canada or the United Canadas) was a British colony in North America from 1841 to 1867. Its formation reflected recommendations made by John Lambton, 1st Earl of Durham, in the Report on the ...
).Oil Museum of Canada, Black Gold: Canada's Oil Heritage, Oil Springs: Boom & Bust
Businessman
James Miller Williams James Miller Williams (September 14, 1818 – November 25, 1890) was a Canadian-American businessman and politician. Williams is best known for establishing the first commercially successful oil well in 1858 and igniting the first oil boom i ...
dug several wells between 1855 and 1858 before discovering a rich reserve of oil four metres below ground. Williams extracted 1.5 million litres of crude oil by 1860, refining much of it into kerosene lamp oil. Williams's well became commercially viable a year before Drake's Pennsylvania operation and could be argued to be the first commercial oil well in North America. The discovery at Oil Springs touched off an
oil boom An oil boom is a period of large inflow of income as a result of high global oil prices or large oil production in an economy. Generally, this short period initially brings economic benefits, in terms of increased GDP growth, but might later lead ...
which brought hundreds of speculators and workers to the area. Advances in drilling continued into 1862 when local driller Shaw reached a depth of 62 metres using the spring-pole drilling method. On January 16, 1862, after an explosion of
natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbo ...
, Canada's first oil gusher came into production, shooting into the air at a recorded rate of per day. By the end of the 19th century the Russian Empire, particularly the
Branobel The Petroleum Production Company Nobel Brothers, Limited, or Branobel (short for братьев Нобель "brat'yev Nobel" — "Nobel Brothers" in Russian), was an oil company set up by Ludvig Nobel and Baron Peter von Bilderling. It operated ...
company in
Azerbaijan Azerbaijan (, ; az, Azərbaycan ), officially the Republic of Azerbaijan, , also sometimes officially called the Azerbaijan Republic is a transcontinental country located at the boundary of Eastern Europe and Western Asia. It is a part of th ...
, had taken the lead in production.Akiner(2004), p. 5 Access to oil was and still is a major factor in several military conflicts of the twentieth century, including
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
, during which oil facilities were a major strategic asset and were extensively bombed. The
German invasion of the Soviet Union Operation Barbarossa (german: link=no, Unternehmen Barbarossa; ) was the invasion of the Soviet Union by Nazi Germany and many of its Axis allies, starting on Sunday, 22 June 1941, during the Second World War. The operation, code-named after ...
included the goal to capture the Baku oilfields, as it would provide much needed oil-supplies for the German military which was suffering from blockades. Oil exploration in North America during the early 20th century later led to the US's becoming the leading producer by mid-century. As petroleum production in the US peaked during the 1960s, however, the United States was surpassed by Saudi Arabia and the Soviet Union. In 1973, Saudi Arabia and other
Arab nations The Arab world ( ar, اَلْعَالَمُ الْعَرَبِيُّ '), formally the Arab homeland ( '), also known as the Arab nation ( '), the Arabsphere, or the Arab states, refers to a vast group of countries, mainly located in Western As ...
imposed an
oil embargo An oil embargo is an economic situation wherein entities engage in an embargo to limit the transport of petroleum to or from an area, in order to exact some desired outcome. One commentator states, " oil embargo is not a common commercial practice; ...
against the United States, United Kingdom, Japan and other Western nations which supported
Israel Israel (; he, יִשְׂרָאֵל, ; ar, إِسْرَائِيل, ), officially the State of Israel ( he, מְדִינַת יִשְׂרָאֵל, label=none, translit=Medīnat Yīsrāʾēl; ), is a country in Western Asia. It is situated ...
in the
Yom Kippur War The Yom Kippur War, also known as the Ramadan War, the October War, the 1973 Arab–Israeli War, or the Fourth Arab–Israeli War, was an armed conflict fought from October 6 to 25, 1973 between Israel and a coalition of Arab states led by Egy ...
of October 1973. The embargo caused an oil crisis. This was followed by the 1979 oil crisis, which was caused by a drop in
oil production Petroleum is a fossil fuel that can be drawn from beneath the earth's surface. Reservoirs of petroleum was formed through the mixture of plants, algae, and sediments in shallow seas under high pressure. Petroleum is mostly recovered from oil dri ...
in the wake of the
Iranian Revolution The Iranian Revolution ( fa, انقلاب ایران, Enqelâb-e Irân, ), also known as the Islamic Revolution ( fa, انقلاب اسلامی, Enqelâb-e Eslâmī), was a series of events that culminated in the overthrow of the Pahlavi dynas ...
and caused oil prices to more than double. The two oil price shocks had many short- and long-term effects on global politics and the global economy. In particular, they led to sustained reductions in demand as a result of substitution to other fuels (especially coal and nuclear) and improvements in energy efficiency, facilitated by government policies. High oil prices also induced investment in oil production by non-OPEC countries, including Prudhoe Bay in Alaska, the North Sea offshore fields of the United Kingdom and Norway, the Cantarell offshore field of Mexico, and oil sands in Canada. Today, about 90 percent of vehicular fuel needs are met by oil. Petroleum also makes up 40 percent of total energy consumption in the United States, but is responsible for only 1 percent of electricity generation. Petroleum's worth as a portable, dense energy source powering the vast majority of vehicles and as the base of many industrial chemicals makes it one of the world's most important
commodities In economics, a commodity is an economic good, usually a resource, that has full or substantial fungibility: that is, the market treats instances of the good as equivalent or nearly so with no regard to who produced them. The price of a comm ...
. The top three oil producing countries are the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
,
Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...
, and
Saudi Arabia Saudi Arabia, officially the Kingdom of Saudi Arabia (KSA), is a country in Western Asia. It covers the bulk of the Arabian Peninsula, and has a land area of about , making it the fifth-largest country in Asia, the second-largest in the A ...
. In 2018, due in part to developments in
hydraulic fracturing Fracking (also known as hydraulic fracturing, hydrofracturing, or hydrofracking) is a well stimulation technique involving the fracturing of bedrock formations by a pressurized liquid. The process involves the high-pressure injection of "frack ...
and
horizontal drilling Directional drilling (or slant drilling) is the practice of drilling non-vertical bores. It can be broken down into four main groups: oilfield directional drilling, utility installation directional drilling, directional boring (horizontal dir ...
, the United States became the world's largest producer. About 80 percent of the world's readily accessible reserves are located in the Middle East, with 62.5 percent coming from the Arab 5:
Saudi Arabia Saudi Arabia, officially the Kingdom of Saudi Arabia (KSA), is a country in Western Asia. It covers the bulk of the Arabian Peninsula, and has a land area of about , making it the fifth-largest country in Asia, the second-largest in the A ...
,
United Arab Emirates The United Arab Emirates (UAE; ar, اَلْإِمَارَات الْعَرَبِيَة الْمُتَحِدَة ), or simply the Emirates ( ar, الِْإمَارَات ), is a country in Western Asia (The Middle East). It is located at th ...
,
Iraq Iraq,; ku, عێراق, translit=Êraq officially the Republic of Iraq, '; ku, کۆماری عێراق, translit=Komarî Êraq is a country in Western Asia. It is bordered by Turkey to Iraq–Turkey border, the north, Iran to Iran–Iraq ...
,
Qatar Qatar (, ; ar, قطر, Qaṭar ; local vernacular pronunciation: ), officially the State of Qatar,) is a country in Western Asia. It occupies the Qatar Peninsula on the northeastern coast of the Arabian Peninsula in the Middle East; it sh ...
and
Kuwait Kuwait (; ar, الكويت ', or ), officially the State of Kuwait ( ar, دولة الكويت '), is a country in Western Asia. It is situated in the northern edge of Eastern Arabia at the tip of the Persian Gulf, bordering Iraq to the nort ...
. A large portion of the world's total oil exists as unconventional sources, such as
bitumen Asphalt, also known as bitumen (, ), is a sticky, black, highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term a ...
in Athabasca oil sands and
extra heavy oil Heavy crude oil (or extra heavy crude oil) is highly-viscous oil that cannot easily flow from production wells under normal reservoir conditions. It is referred to as "heavy" because its density or specific gravity is higher than that of light cr ...
in the Orinoco Belt. While significant volumes of oil are extracted from oil sands, particularly in Canada, logistical and technical hurdles remain, as oil extraction requires large amounts of heat and water, making its net energy content quite low relative to conventional crude oil. Thus, Canada's oil sands are not expected to provide more than a few million barrels per day in the foreseeable future.


Composition

Petroleum includes not only crude oil, but all liquid, gaseous and solid
hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ex ...
s. Under surface pressure and temperature conditions, lighter hydrocarbons
methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Eart ...
,
ethane Ethane ( , ) is an organic chemical compound with chemical formula . At standard temperature and pressure, ethane is a colorless, odorless gas. Like many hydrocarbons, ethane is isolated on an industrial scale from natural gas and as a petr ...
,
propane Propane () is a three-carbon alkane with the molecular formula . It is a gas at standard temperature and pressure, but compressible to a transportable liquid. A by-product of natural gas processing and petroleum refining, it is commonly used a ...
and
butane Butane () or ''n''-butane is an alkane with the formula C4H10. Butane is a gas at room temperature and atmospheric pressure. Butane is a highly flammable, colorless, easily liquefied gas that quickly vaporizes at room temperature. The name but ...
exist as gases, while
pentane Pentane is an organic compound with the formula C5H12—that is, an alkane with five carbon atoms. The term may refer to any of three structural isomers, or to a mixture of them: in the IUPAC nomenclature, however, pentane means exclusively the ' ...
and heavier hydrocarbons are in the form of liquids or solids. However, in an underground
oil reservoir A petroleum reservoir or oil and gas reservoir is a subsurface accumulation of hydrocarbons contained in porous or fractured rock formations. Such reservoirs form when kerogen (ancient plant matter) is created in surrounding rock by the presence ...
the proportions of gas, liquid, and solid depend on subsurface conditions and on the
phase diagram A phase diagram in physical chemistry, engineering, mineralogy, and materials science is a type of chart used to show conditions (pressure, temperature, volume, etc.) at which thermodynamically distinct phases (such as solid, liquid or gaseous ...
of the petroleum mixture. An
oil well An oil well is a drillhole boring in Earth that is designed to bring petroleum oil hydrocarbons to the surface. Usually some natural gas is released as associated petroleum gas along with the oil. A well that is designed to produce only gas may ...
produces predominantly crude oil, with some natural gas dissolved in it. Because the pressure is lower at the surface than underground, some of the gas will come out of
solution Solution may refer to: * Solution (chemistry), a mixture where one substance is dissolved in another * Solution (equation), in mathematics ** Numerical solution, in numerical analysis, approximate solutions within specified error bounds * Soluti ...
and be recovered (or burned) as ''associated gas'' or ''solution gas''. A
gas well An oil well is a drillhole boring in Earth that is designed to bring petroleum oil hydrocarbons to the surface. Usually some natural gas is released as associated petroleum gas along with the oil. A well that is designed to produce only gas m ...
produces predominantly
natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbo ...
. However, because the underground temperature is higher than at the surface, the gas may contain heavier hydrocarbons such as pentane,
hexane Hexane () is an organic compound, a straight-chain alkane with six carbon atoms and has the molecular formula C6H14. It is a colorless liquid, odorless when pure, and with boiling points approximately . It is widely used as a cheap, relatively ...
, and
heptane Heptane or ''n''-heptane is the straight-chain alkane with the chemical formula H3C(CH2)5CH3 or C7H16. When used as a test fuel component in anti-knock test engines, a 100% heptane fuel is the zero point of the octane rating scale (the 100 poin ...
in the
gaseous state Gas is one of the four fundamental state of matter, states of matter (the others being solid, liquid, and plasma (physics), plasma). A pure gas may be made up of individual atoms (e.g. a noble gas like neon), chemical element, elemental molec ...
. At surface conditions these will
condense Condensation is the change of the state of matter from the gas phase into the liquid phase, and is the reverse of vaporization. The word most often refers to the water cycle. It can also be defined as the change in the state of water vapor to ...
out of the gas to form "
natural-gas condensate Natural-gas condensate, also called natural gas liquids, is a low-density mixture of hydrocarbon liquids that are present as gaseous components in the raw natural gas produced from many natural gas fields. Some gas species within the raw natur ...
", often shortened to ''condensate.'' Condensate resembles gasoline in appearance and is similar in composition to some volatile
light crude oil Light crude oil is liquid petroleum that has a low density and flows freely at room temperature. It has a low viscosity, low specific gravity and high API gravity due to the presence of a high proportion of light hydrocarbon fractions. It generally ...
s. The proportion of light hydrocarbons in the petroleum mixture varies greatly among different
oil fields A petroleum reservoir or oil and gas reservoir is a subsurface accumulation of hydrocarbons contained in porous or fractured rock formations. Such reservoirs form when kerogen (ancient plant matter) is created in surrounding rock by the presence ...
, ranging from as much as 97 percent by weight in the lighter oils to as little as 50 percent in the heavier oils and
bitumen Asphalt, also known as bitumen (, ), is a sticky, black, highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term a ...
s. The hydrocarbons in crude oil are mostly
alkane In organic chemistry, an alkane, or paraffin (a historical trivial name that also has other meanings), is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in which ...
s,
cycloalkane In organic chemistry, the cycloalkanes (also called naphthenes, but distinct from naphthalene) are the monocyclic saturated hydrocarbons. In other words, a cycloalkane consists only of hydrogen and carbon atoms arranged in a structure containing ...
s and various
aromatic hydrocarbon Aromatic compounds, also known as "mono- and polycyclic aromatic hydrocarbons", are organic compounds containing one or more aromatic rings. The parent member of aromatic compounds is benzene. The word "aromatic" originates from the past grouping ...
s, while the other organic compounds contain
nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
,
oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
and
sulfur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...
, and trace amounts of metals such as iron, nickel, copper and
vanadium Vanadium is a chemical element with the symbol V and atomic number 23. It is a hard, silvery-grey, malleable transition metal. The elemental metal is rarely found in nature, but once isolated artificially, the formation of an oxide layer ( pas ...
. Many oil reservoirs contain live bacteria. The exact molecular composition of crude oil varies widely from formation to formation but the proportion of
chemical element A chemical element is a species of atoms that have a given number of protons in their nuclei, including the pure substance consisting only of that species. Unlike chemical compounds, chemical elements cannot be broken down into simpler sub ...
s varies over fairly narrow limits as follows: Four different types of hydrocarbon molecules appear in crude oil. The relative percentage of each varies from oil to oil, determining the properties of each oil. Crude oil varies greatly in appearance depending on its composition. It is usually black or dark brown (although it may be yellowish, reddish, or even greenish). In the reservoir it is usually found in association with natural gas, which being lighter forms a "gas cap" over the petroleum, and
saline water Saline water (more commonly known as salt water) is water that contains a high concentration of dissolved salts (mainly sodium chloride). On the United States Geological Survey (USGS) salinity scale, saline water is saltier than brackish water, ...
which, being heavier than most forms of crude oil, generally sinks beneath it. Crude oil may also be found in a semi-solid form mixed with sand and water, as in the Athabasca oil sands in Canada, where it is usually referred to as crude
bitumen Asphalt, also known as bitumen (, ), is a sticky, black, highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term a ...
. In Canada, bitumen is considered a sticky, black, tar-like form of crude oil which is so thick and heavy that it must be heated or diluted before it will flow. Venezuela also has large amounts of oil in the
Orinoco oil sands The Orinoco Belt is a territory in the southern strip of the eastern Orinoco River Basin in Venezuela which overlies the world's largest deposits of petroleum. Its local Spanish language, Spanish name is ''Faja Petrolífera del Orinoco'' (Orinoco P ...
, although the hydrocarbons trapped in them are more fluid than in Canada and are usually called
extra heavy oil Heavy crude oil (or extra heavy crude oil) is highly-viscous oil that cannot easily flow from production wells under normal reservoir conditions. It is referred to as "heavy" because its density or specific gravity is higher than that of light cr ...
. These oil sands resources are called
unconventional oil Unconventional oil is petroleum produced or extracted using techniques other than the conventional method (oil well). Industry and governments across the globe are investing in unconventional oil sources due to the increasing scarcity of conventio ...
to distinguish them from oil which can be extracted using traditional oil well methods. Between them, Canada and
Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...
contain an estimated of bitumen and extra-heavy oil, about twice the volume of the world's reserves of conventional oil. Petroleum is used mostly, by volume, for refining into
fuel oil Fuel oil is any of various fractions obtained from the distillation of petroleum (crude oil). Such oils include distillates (the lighter fractions) and residues (the heavier fractions). Fuel oils include heavy fuel oil, marine fuel oil (MFO), bun ...
and gasoline, both important ''
primary energy Primary energy (PE) is an energy form found in nature that has not been subjected to any human engineered conversion process. It is energy contained in raw fuels, and other forms of energy, including waste, received as input to a system. Pr ...
'' sources. Eight-four percent by volume of the hydrocarbons present in petroleum is converted into energy-rich fuels (petroleum-based fuels), including gasoline, diesel, jet, heating, and other fuel oils, and
liquefied petroleum gas Liquefied petroleum gas (LPG or LP gas) is a fuel gas which contains a flammable mixture of hydrocarbon gases, specifically propane, propylene, butylene, isobutane and n-butane. LPG is used as a fuel gas in heating appliances, cooking e ...
. The lighter grades of crude oil produce the best yields of these products, but as the world's reserves of light and medium oil are depleted,
oil refineries An oil refinery or petroleum refinery is an industrial process plant where petroleum (crude oil) is transformed and refined into useful products such as gasoline (petrol), diesel fuel, asphalt base, fuel oils, heating oil, kerosene, liquefie ...
are increasingly having to process heavy oil and bitumen, and use more complex and expensive methods to produce the products required. Because heavier crude oils have too much carbon and not enough hydrogen, these processes generally involve removing carbon from or adding hydrogen to the molecules, and using
fluid catalytic cracking Fluid Catalytic Cracking (FCC) is the conversion process used in petroleum refineries to convert the high-boiling point, high-molecular weight hydrocarbon fractions of petroleum (crude oils) into gasoline, olefinic gases, and other petroleum prod ...
to convert the longer, more complex molecules in the oil to the shorter, simpler ones in the fuels. Due to its high
energy density In physics, energy density is the amount of energy stored in a given system or region of space per unit volume. It is sometimes confused with energy per unit mass which is properly called specific energy or . Often only the ''useful'' or extract ...
, easy transportability and relative abundance, oil has become the world's most important source of energy since the mid-1950s. Petroleum is also the raw material for many
chemical A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., wi ...
products, including
pharmaceutical A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy (pharmacotherapy) is an important part of the medical field and re ...
s,
solvent A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for ...
s,
fertilizer A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from ...
s,
pesticide Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and lampri ...
s, and plastics; the 16 percent not used for energy production is converted into these other materials. Petroleum is found in
porous Porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0% and 100%. Strictly speaking, some tests measure ...
rock formations A rock formation is an isolated, scenic, or spectacular surface rock outcrop. Rock formations are usually the result of weathering and erosion sculpting the existing rock. The term ''rock formation'' can also refer to specific sediment ...
in the upper
strata In geology and related fields, a stratum ( : strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as ei ...
of some areas of the
Earth's crust Earth's crust is Earth's thin outer shell of rock, referring to less than 1% of Earth's radius and volume. It is the top component of the lithosphere, a division of Earth's layers that includes the crust and the upper part of the mantle. The ...
. There is also petroleum in oil sands (tar sands). Known
oil reserves An oil is any polarity (chemistry), nonpolar chemical substance that is composed primarily of Hydrocarbon, hydrocarbons and is hydrophobe, hydrophobic (does not mix with water) & lipophilicity, lipophilic (mixes with other oils). Oils are usu ...
are typically estimated at 190 km3 (1.2
trillion ''Trillion'' is a number with two distinct definitions: * 1,000,000,000,000, i.e. one million million, or (ten to the twelfth power), as defined on the short scale. This is now the meaning in both American and British English. * 1,000,000,000,0 ...
(short scale)
barrels A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wooden staves and bound by wooden or metal hoops. The word vat is often used for large containers for liquids, u ...
) without oil sands, or 595 km3 (3.74 trillion barrels) with oil sands. Consumption is currently around per day, or 4.9 km3 per year, yielding a remaining oil supply of only about 120 years, if current demand remains static. More recent studies, however, put the number at around 50 years.


Chemistry

Petroleum is mainly a mixture of
hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ex ...
s, i.e. containing only carbon and hydrogen. The most common components are
alkane In organic chemistry, an alkane, or paraffin (a historical trivial name that also has other meanings), is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in which ...
s (paraffins),
cycloalkane In organic chemistry, the cycloalkanes (also called naphthenes, but distinct from naphthalene) are the monocyclic saturated hydrocarbons. In other words, a cycloalkane consists only of hydrogen and carbon atoms arranged in a structure containing ...
s (
naphthene In organic chemistry, the cycloalkanes (also called naphthenes, but distinct from naphthalene) are the monocyclic saturated hydrocarbons. In other words, a cycloalkane consists only of hydrogen and carbon atoms arranged in a structure containing ...
s), and
aromatic hydrocarbon Aromatic compounds, also known as "mono- and polycyclic aromatic hydrocarbons", are organic compounds containing one or more aromatic rings. The parent member of aromatic compounds is benzene. The word "aromatic" originates from the past grouping ...
s. They generally have from 5 to 40 carbon atoms per molecule, although trace amounts of shorter or longer molecules may be present in the mixture. The alkanes from
pentane Pentane is an organic compound with the formula C5H12—that is, an alkane with five carbon atoms. The term may refer to any of three structural isomers, or to a mixture of them: in the IUPAC nomenclature, however, pentane means exclusively the ' ...
(C5H12) to
octane Octane is a hydrocarbon and an alkane with the chemical formula , and the condensed structural formula . Octane has many structural isomers that differ by the amount and location of branching in the carbon chain. One of these isomers, 2,2,4-Tri ...
(C8H18) are refined into gasoline, the ones from
nonane Nonane is a linear alkane hydrocarbon with the chemical formula C9H20. It is a colorless, flammable liquid, occurring primarily in the component of the petroleum distillate fraction commonly called kerosene, which is used as a heating, tractor, ...
(C9H20) to
hexadecane Hexadecane (also called cetane) is an alkane hydrocarbon with the chemical formula C16H34. Hexadecane consists of a chain of 16 carbon atoms, with three hydrogen atoms bonded to the two end carbon atoms, and two hydrogens bonded to each of the ...
(C16H34) into
diesel fuel Diesel fuel , also called diesel oil, is any liquid fuel specifically designed for use in a diesel engine, a type of internal combustion engine in which fuel ignition takes place without a spark as a result of compression of the inlet air and t ...
,
kerosene Kerosene, paraffin, or lamp oil is a combustible hydrocarbon liquid which is derived from petroleum. It is widely used as a fuel in aviation as well as households. Its name derives from el, κηρός (''keros'') meaning "wax", and was regi ...
and
jet fuel Jet fuel or aviation turbine fuel (ATF, also abbreviated avtur) is a type of aviation fuel designed for use in aircraft powered by gas-turbine engines. It is colorless to straw-colored in appearance. The most commonly used fuels for commercial a ...
. Alkanes with more than 16 carbon atoms can be refined into
fuel oil Fuel oil is any of various fractions obtained from the distillation of petroleum (crude oil). Such oils include distillates (the lighter fractions) and residues (the heavier fractions). Fuel oils include heavy fuel oil, marine fuel oil (MFO), bun ...
and lubricating oil. At the heavier end of the range,
paraffin wax Paraffin wax (or petroleum wax) is a soft colorless solid derived from petroleum, coal, or oil shale that consists of a mixture of hydrocarbon molecules containing between 20 and 40 carbon atoms. It is solid at room temperature and begins to m ...
is an alkane with approximately 25 carbon atoms, while
asphalt Asphalt, also known as bitumen (, ), is a sticky, black, highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term a ...
has 35 and up, although these are usually
cracked Cracked may refer to: Television * ''Cracked'' (British TV series), a 2008 British comedy-drama television series that aired on STV * ''Cracked'' (Canadian TV series), a 2013 Canadian crime drama series that aired on CBC * "Cracked", a Season 8 ( ...
by modern refineries into more valuable products. The shortest molecules, those with four or fewer carbon atoms, are in a gaseous state at room temperature. They are the petroleum gases. Depending on demand and the cost of recovery, these gases are either flared off, sold as
liquefied petroleum gas Liquefied petroleum gas (LPG or LP gas) is a fuel gas which contains a flammable mixture of hydrocarbon gases, specifically propane, propylene, butylene, isobutane and n-butane. LPG is used as a fuel gas in heating appliances, cooking e ...
under pressure, or used to power the refinery's own burners. During the winter, butane (C4H10), is blended into the gasoline pool at high rates, because its high vapour pressure assists with cold starts. Liquified under pressure slightly above atmospheric, it is best known for powering cigarette lighters, but it is also a main fuel source for many developing countries. Propane can be liquified under modest pressure, and is consumed for just about every application relying on petroleum for energy, from cooking to heating to transportation. The ''aromatic hydrocarbons'' are
unsaturated hydrocarbons In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond. Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, an ...
which have one or more planar six-carbon rings called
benzene ring Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms, ...
s, to which hydrogen atoms are attached with the formula CnH2n-6. They tend to burn with a sooty flame, and many have a sweet aroma. Some are
carcinogenic A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive substan ...
. These different molecules are separated by
fractional distillation Fractional distillation is the separation of a mixture into its component parts, or fractions. Chemical compounds are separated by heating them to a temperature at which one or more fractions of the mixture will vaporize. It uses distillation to ...
at an oil refinery to produce gasoline, jet fuel, kerosene, and other hydrocarbons. For example, 2,2,4-trimethylpentane (isooctane), widely used in
gasoline Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic co ...
, has a chemical formula of C8H18 and it reacts with oxygen
exothermic In thermodynamics, an exothermic process () is a thermodynamic process or reaction that releases energy from the system to its surroundings, usually in the form of heat, but also in a form of light (e.g. a spark, flame, or flash), electricity (e ...
ally: :2 (''l'') + 25 (''g'') → 16 (''g'') + 18 (''g'') (ΔH = −5.51 MJ/mol of octane) The number of various molecules in an oil sample can be determined by laboratory analysis. The molecules are typically extracted in a
solvent A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for ...
, then separated in a
gas chromatograph Gas chromatography (GC) is a common type of chromatography used in analytical chemistry for separating and analyzing compounds that can be vaporized without decomposition. Typical uses of GC include testing the purity of a particular substance, ...
, and finally determined with a suitable
detector A sensor is a device that produces an output signal for the purpose of sensing a physical phenomenon. In the broadest definition, a sensor is a device, module, machine, or subsystem that detects events or changes in its environment and sends ...
, such as a
flame ionization detector A flame ionization detector (FID) is a scientific instrument that measures analytes in a gas stream. It is frequently used as a detector in gas chromatography. The measurement of ion per unit time make this a mass sensitive instrument. Standalo ...
or a
mass spectrometer Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a '' mass spectrum'', a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is us ...
. Due to the large number of co-eluted hydrocarbons within oil, many cannot be resolved by traditional gas chromatography and typically appear as a hump in the chromatogram. This Unresolved Complex Mixture (UCM) of hydrocarbons is particularly apparent when analysing weathered oils and extracts from tissues of organisms exposed to oil. Some of the components of oil will mix with water: the
water associated fraction The water associated fraction (WAF), sometimes termed the water-soluble fraction (W.S.F.), is the solution of low molecular mass hydrocarbons naturally released from petroleum hydrocarbon mixtures in contact with water. Although generally regarded ...
of the oil. Incomplete combustion of petroleum or gasoline results in production of toxic byproducts. Too little oxygen during combustion results in the formation of
carbon monoxide Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simple ...
. Due to the high temperatures and high pressures involved, exhaust gases from gasoline combustion in car engines usually include
nitrogen oxide Nitrogen oxide may refer to a binary compound of oxygen and nitrogen, or a mixture of such compounds: Charge-neutral *Nitric oxide (NO), nitrogen(II) oxide, or nitrogen monoxide *Nitrogen dioxide (), nitrogen(IV) oxide * Nitrogen trioxide (), or n ...
s which are responsible for creation of
photochemical smog Smog, or smoke fog, is a type of intense air pollution. The word "smog" was coined in the early 20th century, and is a portmanteau of the words ''smoke'' and ''fog'' to refer to smoky fog due to its opacity, and odor. The word was then inten ...
.


Formation


Fossil petroleum

Petroleum is a
fossil fuel A fossil fuel is a hydrocarbon-containing material formed naturally in the Earth's crust from the remains of dead plants and animals that is extracted and burned as a fuel. The main fossil fuels are coal, oil, and natural gas. Fossil fuels m ...
derived from ancient
fossilized A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in ...
organic material Organic matter, organic material, or natural organic matter refers to the large source of carbon-based compounds found within natural and engineered, terrestrial, and aquatic environments. It is matter composed of organic compounds that have c ...
s, such as
zooplankton Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...
and
algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...
. Vast amounts of these remains settled to sea or lake bottoms where they were covered in stagnant water (water with no dissolved
oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
) or
sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand an ...
s such as
mud A MUD (; originally multi-user dungeon, with later variants multi-user dimension and multi-user domain) is a Multiplayer video game, multiplayer Time-keeping systems in games#Real-time, real-time virtual world, usually Text-based game, text-bas ...
and
silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel when ...
faster than they could decompose aerobically. Approximately 1 m below this sediment, water oxygen concentration was low, below 0.1 mg/L, and anoxic conditions existed. Temperatures also remained constant. As further layers settled to the sea or lake bed, intense heat and pressure built up in the lower regions. This process caused the organic matter to change, first into a waxy material known as
kerogen Kerogen is solid, insoluble organic matter in sedimentary rocks. Comprising an estimated 1016 tons of carbon, it is the most abundant source of organic compounds on earth, exceeding the total organic content of living matter 10,000-fold. It ...
, found in various
oil shale Oil shale is an organic-rich fine-grained sedimentary rock containing kerogen (a solid mixture of organic chemical compounds) from which liquid hydrocarbons can be produced. In addition to kerogen, general composition of oil shales constitute ...
s around the world, and then with more heat into liquid and gaseous
hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ex ...
s via a process known as catagenesis. Formation of petroleum occurs from hydrocarbon
pyrolysis The pyrolysis (or devolatilization) process is the thermal decomposition of materials at elevated temperatures, often in an inert atmosphere. It involves a change of chemical composition. The word is coined from the Greek-derived elements ''py ...
in a variety of mainly
endothermic In thermochemistry, an endothermic process () is any thermodynamic process with an increase in the enthalpy (or internal energy ) of the system.Oxtoby, D. W; Gillis, H.P., Butler, L. J. (2015).''Principle of Modern Chemistry'', Brooks Cole. p. ...
reactions at high temperature or pressure, or both. These phases are described in detail below.


Anaerobic decay

In the absence of plentiful oxygen, ''aerobic'' bacteria were prevented from decaying the organic matter after it was buried under a layer of sediment or water. However, ''anaerobic'' bacteria were able to reduce
sulfate The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ar ...
s and
nitrate Nitrate is a polyatomic ion A polyatomic ion, also known as a molecular ion, is a covalent bonded set of two or more atoms, or of a metal complex, that can be considered to behave as a single unit and that has a net charge that is not zer ...
s among the matter to H2S and N2 respectively by using the matter as a source for other reactants. Due to such anaerobic bacteria, at first this matter began to break apart mostly via
hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...
:
polysaccharide Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrates found in food. They are long chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with wa ...
s and
protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
s were hydrolyzed to
simple sugars Monosaccharides (from Greek ''monos'': single, '' sacchar'': sugar), also called simple sugars, are the simplest forms of sugar and the most basic units (monomers) from which all carbohydrates are built. They are usually colorless, water-solub ...
and
amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...
s respectively. These were further anaerobically
oxidized Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a ...
at an accelerated rate by the
enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...
s of the bacteria: e.g., amino acids went through
oxidative deamination Oxidative deamination is a form of deamination that generates α-keto acids and other oxidized products from amine-containing compounds, and occurs primarily in the liver. Oxidative deamination is stereospecific, meaning it contains different stere ...
to
imino acid In organic chemistry, an imino acid is any molecule that contains both imine (>C=NH) and carboxyl (-C(=O)-OH) functional groups. Imino acids are structurally related to amino acids, which have amino group instead of imine—a difference of si ...
s, which in turn reacted further to
ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous was ...
and α-keto acids.
Monosaccharide Monosaccharides (from Greek ''monos'': single, '' sacchar'': sugar), also called simple sugars, are the simplest forms of sugar and the most basic units (monomers) from which all carbohydrates are built. They are usually colorless, water-solub ...
s in turn ultimately decayed to CO2 and
methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Eart ...
. The anaerobic decay products of amino acids, monosaccharides,
phenols In organic chemistry, phenols, sometimes called phenolics, are a class of chemical compounds consisting of one or more hydroxyl groups (— O H) bonded directly to an aromatic hydrocarbon group. The simplest is phenol, . Phenolic compounds are c ...
and
aldehyde In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl grou ...
s combined to
fulvic acid Humic substances (HS) are organic compounds that are important components of humus, the major organic fraction of soil, peat, and coal (and also a constituent of many upland streams, dystrophic lakes, and ocean water). For a long era in the 19th an ...
s.
Fat In nutrition science, nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such chemical compound, compounds, most commonly those that occur in living beings or in food. The term often refers spec ...
s and
wax Waxes are a diverse class of organic compounds that are lipophilic, malleable solids near ambient temperatures. They include higher alkanes and lipids, typically with melting points above about 40 °C (104 °F), melting to giv ...
es were not extensively hydrolyzed under these mild conditions.


Kerogen formation

Some phenolic compounds produced from previous reactions worked as
bactericide A bactericide or bacteriocide, sometimes abbreviated Bcidal, is a substance which kills bacteria. Bactericides are disinfectants, antiseptics, or antibiotics. However, material surfaces can also have bactericidal properties based solely on thei ...
s and the
actinomycetales The Actinomycetales is an order of Actinomycetota. A member of the order is often called an actinomycete. Actinomycetales are generally gram-positive and anaerobic and have mycelia in a filamentous and branching growth pattern. Some actinomycete ...
order of bacteria also produced antibiotic compounds (e.g.,
streptomycin Streptomycin is an antibiotic medication used to treat a number of bacterial infections, including tuberculosis, ''Mycobacterium avium'' complex, endocarditis, brucellosis, ''Burkholderia'' infection, plague, tularemia, and rat bite fever. Fo ...
). Thus the action of anaerobic bacteria ceased at about 10 m below the water or sediment. The mixture at this depth contained fulvic acids, unreacted and partially reacted fats and waxes, slightly modified
lignin Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity ...
, resins and other hydrocarbons. As more layers of organic matter settled to the sea or lake bed, intense heat and pressure built up in the lower regions. As a consequence, compounds of this mixture began to combine in poorly understood ways to
kerogen Kerogen is solid, insoluble organic matter in sedimentary rocks. Comprising an estimated 1016 tons of carbon, it is the most abundant source of organic compounds on earth, exceeding the total organic content of living matter 10,000-fold. It ...
. Combination happened in a similar fashion as
phenol Phenol (also called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it req ...
and
formaldehyde Formaldehyde ( , ) (systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section F ...
molecules react to urea-formaldehyde resins, but kerogen formation occurred in a more complex manner due to a bigger variety of reactants. The total process of kerogen formation from the beginning of anaerobic decay is called diagenesis, a word that means a transformation of materials by dissolution and recombination of their constituents.


Transformation of kerogen into fossil fuels

Kerogen formation continued to the depth of about 1 km from the Earth's surface where temperatures may reach around 50
°C The degree Celsius is the unit of temperature on the Celsius scale (originally known as the centigrade scale outside Sweden), one of two temperature scales used in the International System of Units (SI), the other being the Kelvin scale. The ...
. Kerogen formation represents a halfway point between organic matter and fossil fuels: kerogen can be exposed to oxygen, oxidize and thus be lost, or it could be buried deeper inside the
Earth's crust Earth's crust is Earth's thin outer shell of rock, referring to less than 1% of Earth's radius and volume. It is the top component of the lithosphere, a division of Earth's layers that includes the crust and the upper part of the mantle. The ...
and be subjected to conditions which allow it to slowly transform into fossil fuels like petroleum. The latter happened through catagenesis in which the reactions were mostly
radical Radical may refer to: Politics and ideology Politics *Radical politics, the political intent of fundamental societal change *Radicalism (historical), the Radical Movement that began in late 18th century Britain and spread to continental Europe and ...
rearrangements of kerogen. These reactions took thousands to millions of years and no external reactants were involved. Due to radical nature of these reactions, kerogen reacted towards two classes of products: those with low H/C ratio (
anthracene Anthracene is a solid polycyclic aromatic hydrocarbon (PAH) of formula C14H10, consisting of three fused benzene rings. It is a component of coal tar. Anthracene is used in the Economic production, production of the red dye alizarin and other dyes ...
or products similar to it) and those with high H/C ratio (
methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Eart ...
or products similar to it); i.e., carbon-rich or hydrogen-rich products. Because catagenesis was closed off from external reactants, the resulting composition of the fuel mixture was dependent on the composition of the kerogen via reaction
stoichiometry Stoichiometry refers to the relationship between the quantities of reactants and products before, during, and following chemical reactions. Stoichiometry is founded on the law of conservation of mass where the total mass of the reactants equal ...
. Three types of kerogen exist: type I (algal), II (liptinic) and III (humic), which were formed mainly from
algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...
,
plankton Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankt ...
and
woody plant A woody plant is a plant that produces wood as its structural tissue and thus has a hard stem. In cold climates, woody plants further survive winter or dry season above ground, as opposite to herbaceous plants that die back to the ground until sp ...
s (this term includes
tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...
s,
shrub A shrub (often also called a bush) is a small-to-medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees ...
s and
liana A liana is a long- stemmed, woody vine that is rooted in the soil at ground level and uses trees, as well as other means of vertical support, to climb up to the canopy in search of direct sunlight. The word ''liana'' does not refer to a ta ...
s) respectively. Catagenesis was
pyrolytic The pyrolysis (or devolatilization) process is the thermal decomposition of materials at elevated temperatures, often in an inert atmosphere. It involves a change of chemical composition. The word is coined from the Greek-derived elements ''pyr ...
despite the fact that it happened at relatively low temperatures (when compared to commercial pyrolysis plants) of 60 to several hundred °C. Pyrolysis was possible because of the long reaction times involved. Heat for catagenesis came from the decomposition of
radioactive Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consid ...
materials of the crust, especially 40K, 232Th, 235U and 238U. The heat varied with
geothermal gradient Geothermal gradient is the rate of temperature change with respect to increasing depth in Earth's interior. As a general rule, the crust temperature rises with depth due to the heat flow from the much hotter mantle; away from tectonic plate bo ...
and was typically 10-30 °C per km of depth from the Earth's surface. Unusual
magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural sa ...
intrusions, however, could have created greater localized heating.


Oil window (temperature range)

Geologists often refer to the temperature range in which oil forms as an ''"oil window"''. Below the minimum temperature oil remains trapped in the form of kerogen. Above the maximum temperature the oil is converted to natural gas through the process of
thermal cracking In petrochemistry, petroleum geology and organic chemistry, cracking is the process whereby complex organic molecules such as kerogens or long-chain hydrocarbons are broken down into simpler molecules such as light hydrocarbons, by the breaking of ...
. Sometimes, oil formed at extreme depths may migrate and become trapped at a much shallower level. The Athabasca Oil Sands are one example of this.


Abiogenic petroleum

An alternative mechanism to the one described above was proposed by Russian scientists in the mid-1850s, the hypothesis of
abiogenic petroleum origin The abiogenic petroleum origin is a fringe science which proposes that most of earth's petroleum and natural gas deposits were formed inorganically. Mainstream theories about the formation of hydrocarbons on earth point to an origin from the decompo ...
(petroleum formed by inorganic means), but this is contradicted by geological and
geochemical Geochemistry is the science that uses the tools and principles of chemistry to explain the mechanisms behind major geological systems such as the Earth's crust and its oceans. The realm of geochemistry extends beyond the Earth, encompassing the e ...
evidence. Abiogenic sources of oil have been found, but never in commercially profitable amounts. "The controversy isn't over whether abiogenic oil reserves exist," said Larry Nation of the American Association of Petroleum Geologists. "The controversy is over how much they contribute to Earth's overall reserves and how much time and effort geologists should devote to seeking them out."


Reservoirs

Three conditions must be present for oil reservoirs to form: * a
source rock In petroleum geology, source rock is rock which has generated hydrocarbons or which could generate hydrocarbons. Source rocks are one of the necessary elements of a working petroleum system. They are organic-rich sediments that may have been depos ...
rich in
hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ex ...
material buried deeply enough for subterranean heat to cook it into oil, * a
porous Porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0% and 100%. Strictly speaking, some tests measure ...
and
permeable Permeability, permeable, and semipermeable may refer to: Chemistry *Semipermeable membrane, a membrane which will allow certain molecules or ions to pass through it by diffusion *Vascular permeability, the movement of fluids and molecules betwe ...
reservoir rock where it can accumulate, * a
caprock Caprock or cap rock is a more resistant rock type overlying a less resistant rock type,Kearey, Philip (2001). ''Dictionary of Geology'', 2nd ed., Penguin Reference, London, New York, etc., p. 41.. . analogous to an upper crust on a cake that is har ...
(seal) or other mechanism to prevent the oil 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 less dense than rock or
water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...
, they often migrate upward through adjacent rock layers until either reaching the surface or becoming trapped within porous rocks (known as
reservoirs A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including control ...
) 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 A petroleum reservoir or oil and gas reservoir is a subsurface accumulation of hydrocarbons contained in porous or fractured rock formations. Such reservoirs form when kerogen (ancient plant matter) is created in surrounding rock by the presence ...
forms, from which the liquid can be extracted by
drill A drill is a tool used for making round holes or driving fasteners. It is fitted with a bit, either a drill or driverchuck. Hand-operated types are dramatically decreasing in popularity and cordless battery-powered ones proliferating due to ...
ing and
pump A pump is a device that moves fluids (liquids or gases), or sometimes slurries, by mechanical action, typically converted from electrical energy into hydraulic energy. Pumps can be classified into three major groups according to the method they u ...
ing. 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 Petrochemicals (sometimes abbreviated as petchems) are the chemical products obtained from petroleum by refining. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable sou ...
plants and
oil refineries An oil refinery or petroleum refinery is an industrial process plant where petroleum (crude oil) is transformed and refined into useful products such as gasoline (petrol), diesel fuel, asphalt base, fuel oils, heating oil, kerosene, liquefie ...
. Petroleum has mostly been recovered by
oil drilling An oil well is a drillhole boring in Earth that is designed to bring petroleum oil hydrocarbons to the surface. Usually some natural gas is released as associated petroleum gas along with the oil. A well that is designed to produce only gas may ...
(natural petroleum springs are rare). Drilling is carried out after studies of structural geology (at the reservoir scale), sedimentary basin analysis, and reservoir characterisation (mainly in terms of the
porosity Porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0% and 100%. Strictly speaking, some tests measure ...
and permeability of geologic reservoir structures). Recent improvements to technologies have also led to exploitation of other unconventional reserves such as
oil sands Oil sands, tar sands, crude bitumen, or bituminous sands, are a type of unconventional petroleum deposit. Oil sands are either loose sands or partially consolidated sandstone containing a naturally occurring mixture of sand, clay, and wate ...
and
oil shale Oil shale is an organic-rich fine-grained sedimentary rock containing kerogen (a solid mixture of organic chemical compounds) from which liquid hydrocarbons can be produced. In addition to kerogen, general composition of oil shales constitute ...
. Wells are drilled into oil reservoirs to extract the crude oil. "Natural lift" production methods that rely on the natural reservoir pressure to force the oil to the surface are usually sufficient for a while after reservoirs are first tapped. In some reservoirs, such as in the Middle East, the natural pressure is sufficient over a long time. The natural pressure in most reservoirs, however, eventually dissipates. Then the oil must be extracted using "
artificial lift Artificial lift refers to the use of artificial means to increase the flow of liquids, such as crude oil or water, from a production well. Generally this is achieved by the use of a mechanical device inside the well (known as pump or velocity strin ...
" means. Over time, these "primary" methods become less effective and "secondary" production methods may be used. A common secondary method is "waterflood" or injection of water into the reservoir to increase pressure and force the oil to the drilled shaft or "wellbore." Eventually "tertiary" or "enhanced" oil recovery methods may be used to increase the oil's flow characteristics by injecting steam, carbon dioxide and other gases or chemicals into the reservoir. In the United States, primary production methods account for less than 40 percent of the oil produced on a daily basis, secondary methods account for about half, and tertiary recovery the remaining 10 percent. Extracting oil (or "bitumen") from oil/tar sand and oil shale deposits requires mining the sand or shale and heating it in a vessel or retort, or using "in-situ" methods of injecting heated liquids into the deposit and then pumping the liquid back out saturated with oil.


Unconventional oil reservoirs

Oil-eating bacteria
biodegrade Biodegradation is the breakdown of organic matter by microorganisms, such as bacteria and fungi. It is generally assumed to be a natural process, which differentiates it from composting. Composting is a human-driven process in which biodegradati ...
oil that has escaped to the surface.
Oil sands Oil sands, tar sands, crude bitumen, or bituminous sands, are a type of unconventional petroleum deposit. Oil sands are either loose sands or partially consolidated sandstone containing a naturally occurring mixture of sand, clay, and wate ...
are reservoirs of partially biodegraded oil still in the process of escaping and being biodegraded, but they contain so much migrating oil that, although most of it has escaped, vast amounts are still present—more than can be found in conventional oil reservoirs. The lighter fractions of the crude oil are destroyed first, resulting in reservoirs containing an extremely heavy form of crude oil, called crude bitumen in Canada, or extra-heavy crude oil in
Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...
. These two countries have the world's largest deposits of oil sands. On the other hand, oil shales are source rocks that have not been exposed to heat or pressure long enough to convert their trapped hydrocarbons into crude oil. Technically speaking, oil shales are not always shales and do not contain oil, but are fined-grain sedimentary rocks containing an insoluble organic solid called
kerogen Kerogen is solid, insoluble organic matter in sedimentary rocks. Comprising an estimated 1016 tons of carbon, it is the most abundant source of organic compounds on earth, exceeding the total organic content of living matter 10,000-fold. It ...
. The kerogen in the rock can be converted into crude oil using heat and pressure to simulate natural processes. The method has been known for centuries and was patented in 1694 under British Crown Patent No. 330 covering, "A way to extract and make great quantities of pitch, tar, and oil out of a sort of stone." Although oil shales are found in many countries, the United States has the world's largest deposits.


Classification

The
petroleum industry The petroleum industry, also known as the oil industry or the oil patch, includes the global processes of exploration, extraction, refining, transportation (often by oil tankers and pipelines), and marketing of petroleum products. The larges ...
generally classifies crude oil by the geographic location it is produced in (e.g.,
West Texas Intermediate West Texas Intermediate (WTI) is a grade or mix of crude oil; the term is also used to refer to the spot price, the futures price, or assessed price for that oil. In colloquial usage, WTI usually refers to the WTI Crude Oil futures contract tr ...
, Brent, or
Oman Oman ( ; ar, عُمَان ' ), officially the Sultanate of Oman ( ar, سلْطنةُ عُمان ), is an Arabian country located in southwestern Asia. It is situated on the southeastern coast of the Arabian Peninsula, and spans the mouth of t ...
), its
API gravity The American Petroleum Institute gravity, or API gravity, is a measure of how heavy or light a petroleum liquid is compared to water: if its API gravity is greater than 10, it is lighter and floats on water; if less than 10, it is heavier and sinks ...
(an oil industry measure of density), and its sulfur content. Crude oil may be considered ''
light Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 tera ...
'' if it has low density, ''
heavy Heavy may refer to: Measures * Heavy (aeronautics), a term used by pilots and air traffic controllers to refer to aircraft capable of 300,000 lbs or more takeoff weight * Heavy, a characterization of objects with substantial weight * Heavy, ...
'' if it has high density, or ''medium'' if it has a density between that of ''light'' and ''heavy''. Additionally, it may be referred to as ''
sweet Sweetness is a basic taste most commonly perceived when eating foods rich in sugars. Sweet tastes are generally regarded as pleasurable. In addition to sugars like sucrose, many other chemical compounds are sweet, including aldehydes, ketones ...
'' if it contains relatively little sulfur or ''
sour The gustatory system or sense of taste is the sensory system that is partially responsible for the perception of taste (flavor). Taste is the perception produced or stimulated when a substance in the mouth reacts chemically with taste receptor ...
'' 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 revealed by the use of
Crude oil assay A crude oil assay is the chemical evaluation of crude oil feedstocks by petroleum testing laboratories. Each crude oil type has unique molecular and chemical characteristics. No two crude oil types are identical and there are crucial differences in ...
analysis in petroleum laboratories.
Barrels A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wooden staves and bound by wooden or metal hoops. The word vat is often used for large containers for liquids, u ...
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 Reference is a relationship between objects in which one object designates, or acts as a means by which to connect to or link to, another object. The first object in this relation is said to ''refer to'' the second object. It is called a ''name'' ...
throughout the world. Some of the common reference crudes are: *
West Texas Intermediate West Texas Intermediate (WTI) is a grade or mix of crude oil; the term is also used to refer to the spot price, the futures price, or assessed price for that oil. In colloquial usage, WTI usually refers to the WTI Crude Oil futures contract tr ...
(WTI), a very high-quality, sweet, light oil delivered at
Cushing, Oklahoma Cushing ( sac, Koshineki, iow, Amína P^óp^oye Chína, ''meaning: "Soft-seat town"'') is a city in Payne County, Oklahoma, United States. The population was 7,826 at the time of the 2010 census, a decline of 6.5% since 8,371 in 2000. Cushing w ...
for North American oil *
Brent Blend Brent Crude may refer to any or all of the components of the Brent Complex, a physically and financially traded oil market based around the North Sea of Northwest Europe; colloquially, Brent Crude usually refers to the price of the ICE (Intercon ...
, consisting of 15 oils from fields in the Brent and
Ninian Ninian is a Christian saint, first mentioned in the 8th century as being an early missionary among the Pictish peoples of what is now Scotland. For this reason he is known as the Apostle to the Southern Picts, and there are numerous dedicatio ...
systems in the
East Shetland Basin The East Shetland Basin is a major oil-producing area of the North Sea between Scotland and Norway. Oil produced in the UK area is landed at Sullom Voe Terminal in the Shetland Islands. Associated gas flows via the FLAGS, FLAGS pipeline to St Fe ...
of the
North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian S ...
. The oil is landed at
Sullom Voe Sullom Voe is an inlet of the North Sea between the parishes of Delting and Northmavine in Shetland, Scotland. It is a location of the Sullom Voe oil terminal and Shetland Gas Plant. The word Voe is from the Old Norse ' and denotes a small ba ...
terminal in
Shetland Shetland, also called the Shetland Islands and formerly Zetland, is a subarctic archipelago in Scotland lying between Orkney, the Faroe Islands and Norway. It is the northernmost region of the United Kingdom. The islands lie about to the no ...
. Oil production from Europe, Africa and Middle Eastern oil flowing West tends to be priced off this oil, which forms a
benchmark Benchmark may refer to: Business and economics * Benchmarking, evaluating performance within organizations * Benchmark price * Benchmark (crude oil), oil-specific practices Science and technology * Benchmark (surveying), a point of known elevati ...
* Dubai-Oman, used as benchmark for Middle East sour crude oil flowing to the Asia-Pacific region * Tapis (from
Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, thirteen states and three federal territories, separated by the South China Sea into two r ...
, used as a reference for light Far East oil) * Minas (from
Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...
, used as a reference for heavy Far East oil) * The
OPEC Reference Basket The OPEC Reference Basket (ORB), also referred to as the OPEC Basket, is a weighted average of prices for petroleum blends produced by OPEC members. It is used as an important benchmark for crude oil prices. OPEC has often attempted to keep the p ...
, a weighted average of oil blends from various
OPEC The Organization of the Petroleum Exporting Countries (OPEC, ) is a cartel of countries. Founded on 14 September 1960 in Baghdad by the first five members (Iran, Iraq, Kuwait, Saudi Arabia, and Venezuela), it has, since 1965, been headquart ...
(The Organization of the Petroleum Exporting Countries) countries * Midway Sunset Heavy, by which heavy oil in California is priced *
Western Canadian Select Western Canadian Select (WCS) is a heavy sour blend of crude oil that is one of North America's largest heavy crude oil streams and, historically, its cheapest. It was established in December 2004 as a new heavy oil stream by EnCana (now Cenov ...
the benchmark crude oil for emerging heavy, high TAN (acidic) crudes. 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 Hardisty may refer to: * Hardisty (surname) *Hardisty, Alberta, a town in Canada *Hardisty, an area in Edmonton, Alberta, Canada; usually defined as encompassing the neighbourhoods of Fulton Place, Capilano, Forest Heights, Gold Bar, and Terrace ...
,
Alberta Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Ter ...
, and for a Brent Blend delivered at Shetland, it may be a discounted Russian Export Blend delivered at the port of Primorsk. Once extracted, oil is refined and separated, most easily by
distillation Distillation, or classical distillation, is the process of separation process, separating the components or substances from a liquid mixture by using selective boiling and condensation, usually inside an apparatus known as a still. Dry distilla ...
, into numerous products for direct use or use in manufacturing, such as
petrol Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic co ...
(gasoline),
diesel Diesel may refer to: * Diesel engine, an internal combustion engine where ignition is caused by compression * Diesel fuel, a liquid fuel used in diesel engines * Diesel locomotive, a railway locomotive in which the prime mover is a diesel engin ...
and
kerosene Kerosene, paraffin, or lamp oil is a combustible hydrocarbon liquid which is derived from petroleum. It is widely used as a fuel in aviation as well as households. Its name derives from el, κηρός (''keros'') meaning "wax", and was regi ...
to
asphalt Asphalt, also known as bitumen (, ), is a sticky, black, highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term a ...
and chemical
reagent In chemistry, a reagent ( ) or analytical reagent is a substance or compound added to a system to cause a chemical reaction, or test if one occurs. The terms ''reactant'' and ''reagent'' are often used interchangeably, but reactant specifies a ...
s (
ethylene Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon-carbon double bonds). Ethylene i ...
,
propylene Propylene, also known as propene, is an unsaturated organic compound with the chemical formula CH3CH=CH2. It has one double bond, and is the second simplest member of the alkene class of hydrocarbons. It is a colorless gas with a faint petrole ...
,
butene Butene, also known as butylene, is an alkene with the formula . The word ''butene'' may refer to any of the individual compounds. They are colourless gases that are present in crude oil as a minor constituent in quantities that are too small for ...
,
acrylic acid Acrylic acid (IUPAC: propenoic acid) is an organic compound with the formula CH2=CHCOOH. It is the simplest unsaturated carboxylic acid, consisting of a vinyl group connected directly to a carboxylic acid terminus. This colorless liquid has a ...
,
para-xylene ''p''-Xylene ( ''para''-xylene) is an aromatic hydrocarbon. It is one of the three isomers of dimethylbenzene known collectively as xylenes. The ''p-'' stands for ''para-'', indicating that the two methyl groups in ''p''-xylene occupy the diame ...
) used to make
plastic Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptab ...
s,
pesticide Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and lampri ...
s and
pharmaceuticals A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy (pharmacotherapy) is an important part of the medical field and rel ...
.


Industry


Transport

In the 1950s, shipping costs made up 33 percent of the price of oil transported from the
Persian Gulf The Persian Gulf ( fa, خلیج فارس, translit=xalij-e fârs, lit=Gulf of Persis, Fars, ), sometimes called the ( ar, اَلْخَلِيْجُ ٱلْعَرَبِيُّ, Al-Khalīj al-ˁArabī), is a Mediterranean sea (oceanography), me ...
to the United States, but due to the development of
supertankers An oil tanker, also known as a petroleum tanker, is a ship designed for the bulk transport of oil or its products. There are two basic types of oil tankers: crude tankers and product tankers. Crude tankers move large quantities of unrefined cru ...
in the 1970s, the cost of shipping dropped to only 5 percent of the price of Persian oil in the US. Due to the increase of the value of the crude oil during the last 30 years, the share of the shipping cost on the final cost of the delivered commodity was less than 3% in 2010.


Price


Trade

Crude oil is traded as a future on the Nymex exchange. Futures contracts are agreements in which buyers and sellers agree to purchase and deliver specific amounts of physical crude oil on a given date in the future. Each contract covers 1000 barrels and can be purchased up to nine years into the future. Below are the contract specifications for crude oil:


Uses

The chemical structure of petroleum is
heterogeneous Homogeneity and heterogeneity are concepts often used in the sciences and statistics relating to the uniformity of a substance or organism. A material or image that is homogeneous is uniform in composition or character (i.e. color, shape, siz ...
, composed of hydrocarbon chains of different lengths. Because of this, petroleum may be taken to
oil refineries An oil refinery or petroleum refinery is an industrial process plant where petroleum (crude oil) is transformed and refined into useful products such as gasoline (petrol), diesel fuel, asphalt base, fuel oils, heating oil, kerosene, liquefie ...
and the hydrocarbon chemicals separated by
distillation Distillation, or classical distillation, is the process of separation process, separating the components or substances from a liquid mixture by using selective boiling and condensation, usually inside an apparatus known as a still. Dry distilla ...
and treated by other
chemical process In a scientific sense, a chemical process is a method or means of somehow changing one or more chemicals or chemical compounds. Such a chemical process can occur by itself or be caused by an outside force, and involves a chemical reaction of some ...
es, to be used for a variety of purposes. The total cost per plant is about 9 billion dollars.


Fuels

The most common distillation fractions of petroleum are
fuel A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work. The concept was originally applied solely to those materials capable of releasing chemical energy but ...
s. Fuels include (by increasing boiling temperature range): Petroleum classification according to chemical composition.


Other derivatives

Certain types of resultant hydrocarbons may be mixed with other non-hydrocarbons, to create other end products: *
Alkenes In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond. Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, an ...
(olefins), which can be manufactured into plastics or other compounds *
Lubricant A lubricant (sometimes shortened to lube) is a substance that helps to reduce friction between surfaces in mutual contact, which ultimately reduces the heat generated when the surfaces move. It may also have the function of transmitting forces, t ...
s (produces light machine oils,
motor oil Motor oil, engine oil, or engine lubricant is any one of various substances used for the lubrication of internal combustion engines. They typically consist of base oils enhanced with various additives, particularly antiwear additives, deterg ...
s, and greases, adding
viscosity The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the inte ...
stabilizers as required) *
Wax Waxes are a diverse class of organic compounds that are lipophilic, malleable solids near ambient temperatures. They include higher alkanes and lipids, typically with melting points above about 40 °C (104 °F), melting to giv ...
, used in the packaging of
frozen food Freezing food preserves it from the time it is prepared to the time it is eaten. Since early times, farmers, fishermen, and trappers have preserved grains and produce in unheated buildings during the winter season. Freezing food slows decompositi ...
s, among others *
Sulfur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...
or
sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular formu ...
. These are useful industrial materials. Sulfuric acid is usually prepared as the acid precursor
oleum Oleum (Latin ''oleum'', meaning oil), or fuming sulfuric acid, is a term referring to solutions of various compositions of sulfur trioxide in sulfuric acid, or sometimes more specifically to disulfuric acid (also known as pyrosulfuric acid). Ole ...
, a byproduct of sulfur removal from fuels. * Bulk
tar Tar is a dark brown or black viscous liquid of hydrocarbons and free carbon, obtained from a wide variety of organic materials through destructive distillation. Tar can be produced from coal, wood, petroleum, or peat. "a dark brown or black bit ...
*
Asphalt Asphalt, also known as bitumen (, ), is a sticky, black, highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term a ...
*
Petroleum coke Petroleum coke, abbreviated coke or petcoke, is a final carbon-rich solid material that derives from oil refining, and is one type of the group of fuels referred to as cokes. Petcoke is the coke that, in particular, derives from a final cracki ...
, used in speciality carbon products or as solid fuel *
Paraffin wax Paraffin wax (or petroleum wax) is a soft colorless solid derived from petroleum, coal, or oil shale that consists of a mixture of hydrocarbon molecules containing between 20 and 40 carbon atoms. It is solid at room temperature and begins to m ...
*
Aromatic In chemistry, aromaticity is a chemical property of cyclic ( ring-shaped), ''typically'' planar (flat) molecular structures with pi bonds in resonance (those containing delocalized electrons) that gives increased stability compared to satur ...
petrochemical Petrochemicals (sometimes abbreviated as petchems) are the chemical products obtained from petroleum by refining. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable sou ...
s to be used as precursors in other
chemical A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., wi ...
production


Use by country


Consumption statistics

File:Global Carbon Emissions.svg, Global fossil carbon emissions, an indicator of consumption, from 1800. File:World energy consumption.svg, Rate of world energy usage per year from 1970.BP
Statistical Review of World Energy
, Workbook (xlsx), London, 2012
File:Oil consumption per day by region from 1980 to 2006.svg, Daily oil consumption from 1980 to 2006. File:Oil consumption per day by region from 1980 to 2006 solid3.svg, Oil consumption by percentage of total per region from 1980 to 2006: . File:World oil consumption 1980 to 2007 by region.svg, Oil consumption 1980 to 2007 by region.


Consumption

According to the US Energy Information Administration (EIA) estimate for 2017, the world consumes 98.8 million barrels of oil each day. This table orders the amount of petroleum consumed in 2011 in thousand
barrels A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wooden staves and bound by wooden or metal hoops. The word vat is often used for large containers for liquids, u ...
(1000 bbl) per day and in thousand cubic metres (1000 m3) per day: Source
US Energy Information Administration
Population Data: 1 peak production of oil already passed in this state 2 This country is not a major oil producer


Production

In petroleum industry parlance, ''production'' refers to the quantity of crude extracted from reserves, not the literal creation of the product.


Exportation

In order of net exports in 2011, 2009 and 2006 in thousand
bbl A barrel is one of several units of volume applied in various contexts; there are dry barrels, fluid barrels (such as the U.K. beer barrel and U.S. beer barrel), oil barrels, and so forth. For historical reasons the volumes of some barrel units ...
/ d and thousand m3/d: Source
US Energy Information Administration
1 peak production already passed in this state 2 Canadian statistics are complicated by the fact it is both an importer and exporter of crude oil, and refines large amounts of oil for the U.S. market. It is the leading source of U.S. imports of oil and products, averaging in August 2007. Total world production/consumption (as of 2005) is approximately .


Importation

In order of net imports in 2011, 2009 and 2006 in thousand
bbl A barrel is one of several units of volume applied in various contexts; there are dry barrels, fluid barrels (such as the U.K. beer barrel and U.S. beer barrel), oil barrels, and so forth. For historical reasons the volumes of some barrel units ...
/ d and thousand m3/d: Source
US Energy Information Administration


Non-producing consumers

Countries whose oil production is 10% or less of their consumption. Source


Environmental effects


Climate change

, about a quarter of annual global
greenhouse gas emissions Greenhouse gas emissions from human activities strengthen the greenhouse effect, contributing to climate change. Most is carbon dioxide from burning fossil fuels: coal, oil, and natural gas. The largest emitters include coal in China and lar ...
is the carbon dioxide from burning petroleum (plus methane leaks from the industry). Along with the burning of coal, petroleum combustion is the largest contributor to the increase in atmospheric CO2. Atmospheric CO2 has risen over the last 150 years to current levels of over 415  ppmv, from the 180–300 ppmv of the prior 800 thousand years. The rise in Arctic temperature has reduced the minimum
Arctic ice pack The Arctic ice pack is the sea ice cover of the Arctic Ocean and its vicinity. The Arctic ice pack undergoes a regular seasonal cycle in which ice melts in spring and summer, reaches a minimum around mid-September, then increases during fall a ...
to , a loss of almost half since satellite measurements started in 1979.
Ocean acidification Ocean acidification is the reduction in the pH value of the Earth’s ocean. Between 1751 and 2021, the average pH value of the ocean surface has decreased from approximately 8.25 to 8.14. The root cause of ocean acidification is carbon dioxid ...
is the increase in the acidity of the Earth's oceans caused by the uptake of
carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...
() from the
atmosphere An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A s ...
. This increase in acidity inhibits all marine life—having a greater impact on smaller organisms as well as shelled organisms (see
scallops Scallop () is a common name that encompasses various species of marine bivalve mollusks in the taxonomic family Pectinidae, the scallops. However, the common name "scallop" is also sometimes applied to species in other closely related famil ...
).


Extraction

Oil extraction is simply the removal of oil from the reservoir (oil pool). Oil is often recovered as a water-in-oil emulsion, and
specialty chemicals Speciality chemicals (also called specialties or effect chemicals) are particular chemical products which provide a wide variety of effects on which many other industry sectors rely. Some of the categories of speciality chemicals are adhesives, agr ...
called
demulsifiers Demulsifiers, or emulsion breakers, are a class of specialty chemicals used to separate emulsions, for example, water in oil. They are commonly used in the processing of crude oil, which is typically produced along with significant quantities of s ...
are used to separate the oil from water. Oil extraction is costly and often environmentally damaging. Offshore exploration and extraction of oil disturb the surrounding marine environment.


Oil spills

Crude oil and refined fuel spills from
tanker ship A tanker (or tank ship or tankship) is a ship designed to transport or store liquids or gases in bulk. Major types of tankship include the oil tanker, the chemical tanker, and gas carrier. Tankers also carry commodities such as vegetable oils, ...
accidents have damaged natural
ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...
s and human livelihoods in
Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S., ...
, the
Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...
, the
Galápagos Islands The Galápagos Islands (Spanish: , , ) are an archipelago of volcanic islands. They are distributed on each side of the equator in the Pacific Ocean, surrounding the centre of the Western Hemisphere, and are part of the Republic of Ecuador ...
, France and many other places. The quantity of oil spilled during accidents has ranged from a few hundred tons to several hundred thousand tons (e.g.,
Deepwater Horizon oil spill The ''Deepwater Horizon'' oil spill (also referred to as the "BP oil spill") was an industrial disaster that began on 20 April 2010 off of the coast of the United States in the Gulf of Mexico on the BP-operated Macondo Prospect, considered ...
, SS Atlantic Empress,
Amoco Cadiz ''Amoco Cadiz'' was a VLCC (very large crude carrier) owned by Amoco Transport Corp and transporting crude oil for Shell Oil. Operating under the Liberian flag of convenience, she ran aground on 16 March 1978 on Portsall Rocks, from the coa ...
). Smaller spills have already proven to have a great impact on ecosystems, such as the ''Exxon Valdez'' oil spill. Oil spills at sea are generally much more damaging than those on land, since they can spread for hundreds of nautical miles in a thin
oil slick An oil spill is the release of a liquid petroleum hydrocarbon into the environment, especially the marine ecosystem, due to human activity, and is a form of pollution. The term is usually given to marine oil spills, where oil is released into th ...
which can cover beaches with a thin coating of oil. This can kill sea birds, mammals, shellfish and other organisms it coats. Oil spills on land are more readily containable if a makeshift earth dam can be rapidly
bulldozed A bulldozer or dozer (also called a crawler) is a large, motorized machine equipped with a metal blade to the front for pushing material: soil, sand, snow, rubble, or rock during construction work. It travels most commonly on continuous track ...
around the spill site before most of the oil escapes, and land animals can avoid the oil more easily. Control of oil spills is difficult, requires ad hoc methods, and often a large amount of manpower. The dropping of bombs and incendiary devices from aircraft on the wreck produced poor results; modern techniques would include pumping the oil from the wreck, like in the ''Prestige'' oil spill or the ''Erika'' oil spill. Though crude oil is predominantly composed of various hydrocarbons, certain nitrogen heterocyclic compounds, such as
pyridine Pyridine is a basic heterocyclic organic compound with the chemical formula . It is structurally related to benzene, with one methine group replaced by a nitrogen atom. It is a highly flammable, weakly alkaline, water-miscible liquid with a d ...
,
picoline Picoline refers to any of three isomers of methylpyridine (CH3C5H4N). They are all colorless liquids with a characteristic smell similar to that of pyridine. They are miscible with water and most organic solvents. The CAS number of an unspecified ...
, and
quinoline Quinoline is a heterocyclic aromatic organic compound with the chemical formula C9H7N. It is a colorless hygroscopic liquid with a strong odor. Aged samples, especially if exposed to light, become yellow and later brown. Quinoline is only sli ...
are reported as contaminants associated with crude oil, as well as facilities processing oil shale or coal, and have also been found at legacy wood treatment sites. These compounds have a very high water solubility, and thus tend to dissolve and move with water. Certain naturally occurring bacteria, such as ''
Micrococcus ''Micrococcus'' (mi’ krō kŏk’ Əs) is a genus of bacteria in the Micrococcaceae family. ''Micrococcus'' occurs in a wide range of environments, including water, dust, and soil. Micrococci have Gram-positive spherical cells ranging from abo ...
'', '' Arthrobacter'', and ''
Rhodococcus ''Rhodococcus'' is a genus of aerobic, nonsporulating, nonmotile Gram-positive bacteria closely related to ''Mycobacterium'' and ''Corynebacterium''. While a few species are pathogenic, most are benign, and have been found to thrive in a broad ...
'' have been shown to degrade these contaminants. Because petroleum is a naturally occurring substance, its presence in the environment need not be the result of human causes such as accidents and routine activities (
seismic Seismology (; from Ancient Greek σεισμός (''seismós'') meaning "earthquake" and -λογία (''-logía'') meaning "study of") is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other ...
exploration,
drilling Drilling is a cutting process where a drill bit is spun to cut a hole of circular cross-section in solid materials. The drill bit is usually a rotary cutting tool, often multi-point. The bit is pressed against the work-piece and rotated at ra ...
, extraction, refining and combustion). Phenomena such as seeps and
tar pit Tar pits, sometimes referred to as asphalt pits, are large asphalt deposits. They form in the presence of oil, which is created when decayed organic matter is subjected to pressure underground. If this crude oil seeps upward via fractures, co ...
s are examples of areas that petroleum affects without man's involvement.


Tarballs

A tarball is a blob of crude oil (not to be confused with
tar Tar is a dark brown or black viscous liquid of hydrocarbons and free carbon, obtained from a wide variety of organic materials through destructive distillation. Tar can be produced from coal, wood, petroleum, or peat. "a dark brown or black bit ...
, which is a man-made product derived from pine trees or refined from petroleum) which has been weathered after floating in the ocean. Tarballs are an aquatic
pollutant A pollutant or novel entity is a substance or energy introduced into the environment that has undesired effects, or adversely affects the usefulness of a resource. These can be both naturally forming (i.e. minerals or extracted compounds like oi ...
in most environments, although they can occur naturally, for example in the Santa Barbara Channel of California or in the Gulf of Mexico off Texas. Their concentration and features have been used to assess the extent of
oil spills An oil spill is the release of a liquid petroleum hydrocarbon into the environment, especially the marine ecosystem, due to human activity, and is a form of pollution. The term is usually given to marine oil spills, where oil is released into th ...
. Their composition can be used to identify their sources of origin, and tarballs themselves may be dispersed over long distances by deep sea currents. They are slowly decomposed by bacteria, including ''
Chromobacterium violaceum ''Chromobacterium violaceum'' is a Gram-negative, facultative anaerobic, non-sporing coccobacillus. It is motile with the help of a single flagellum which is located at the pole of the coccobacillus. Usually, there are one or two more lateral f ...
'', ''
Cladosporium resinae ''Amorphotheca resinae'' is an ascomycete fungus of the family Amorphothecaceae which is known to thrive in environments containing alkanes (and water), like aviation fuel, from which it derives its trivial name 'kerosene fungus'. As such it ...
'', ''
Bacillus submarinus ''Bacillus submarinus'' is a species in the genus ''Bacillus,'' meaning it is rod shaped while being capable of producing endospores. ''B. submarinus'' is Gram + , where there is a thick layer of peptidoglycan in its cell wall. Description ''Bac ...
'', ''
Micrococcus varians ''Micrococcus'' (mi’ krō kŏk’ Əs) is a genus of bacteria in the Micrococcaceae family (biology), family. ''Micrococcus'' occurs in a wide range of environments, including water, dust, and soil. Micrococci have Gram-positive spherical cell ...
'', ''
Pseudomonas aeruginosa ''Pseudomonas aeruginosa'' is a common encapsulated, gram-negative, aerobic–facultatively anaerobic, rod-shaped bacterium that can cause disease in plants and animals, including humans. A species of considerable medical importance, ''P. aerugi ...
'', '' Candida marina'' and '' Saccharomyces estuari''.


Whales

James S. Robbins has argued that the advent of petroleum-refined kerosene saved some species of great whales from
extinction Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
by providing an inexpensive substitute for
whale oil Whale oil is oil obtained from the blubber of whales. Whale oil from the bowhead whale was sometimes known as train oil, which comes from the Dutch word ''traan'' ("tears, tear" or "drop"). Sperm oil, a special kind of oil obtained from the ...
, thus eliminating the economic imperative for open-boat
whaling Whaling is the process of hunting of whales for their usable products such as meat and blubber, which can be turned into a type of oil that became increasingly important in the Industrial Revolution. It was practiced as an organized industry ...
, but others say that fossil fuels increased whaling with most whales being killed in the 20th century.


Alternatives

In 2018 road transport used 49% of petroleum, aviation 8%, and uses other than energy 17%.
Electric vehicle An electric vehicle (EV) is a vehicle that uses one or more electric motors for propulsion. It can be powered by a collector system, with electricity from extravehicular sources, or it can be powered autonomously by a battery (sometimes cha ...
s are the main alternative for road transport and
biojet An aviation biofuel or bio-jet fuel Note: About">Investable Universe>About' or bio-aviation fuel (BAF) is a biofuel used to power aircraft and is said to be a sustainable aviation fuel (SAF). The International Air Transport Association (IATA) ...
for aviation. Single-use plastics have a high carbon footprint and may pollute the sea, but as of 2022 the best alternatives are unclear.


International relations

Control of petroleum production has been a significant driver of international relations during much of the 20th and 21st centuries. Organizations like OPEC have played an outsized role in international politics. Some historians and commentators have called this the "
Age of Oil The Age of Oil, also known as the Oil Age, the Petroleum Age, or the Oil Boom, refers to the era in human history characterised by an increased use of petroleum in products and as fuel. Though unrefined petroleum has been used for various purposes ...
" With the rise of
renewable energy Renewable energy is energy that is collected from renewable resources that are naturally replenished on a human timescale. It includes sources such as sunlight, wind, the movement of water, and geothermal heat. Although most renewable energy ...
and addressing
climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
some commentators expect a realignment of international power away from
petrostate A petrostate or oil state is a nation whose economy is heavily dependent on the extraction and export of oil or natural gas. The presence alone of large oil and gas industries does not define a petrostate; countries like Norway, Canada, and the Uni ...
s.


Corruption

"Oil rents" have been described as connected with corruption in political literature. A 2011 study suggested that increases in oil rents increased corruption in countries with heavy government involvement in the production of oil. The study found that increases in oil rents "significantly deteriorates political rights". The researchers noted oil exploitation gave politicians "an incentive to extend civil liberties but reduce political rights in the presence of oil windfalls to evade redistribution and conflict".


Conflict

Petroleum production can be linked with conflict: whether through direct aggression, trade wars such as the 2020 Russia–Saudi Arabia oil price war, or by indirectly funding aggressors, such as the
Islamic State of Iraq and the Levant An Islamic state is a State (polity), state that has a form of government based on sharia, Islamic law (sharia). As a term, it has been used to describe various historical Polity, polities and theories of governance in the Islamic world. As a t ...
.


OPEC


Future production

Consumption Consumption may refer to: *Resource consumption *Tuberculosis, an infectious disease, historically * Consumption (ecology), receipt of energy by consuming other organisms * Consumption (economics), the purchasing of newly produced goods for curren ...
in the twentieth and twenty-first centuries has been abundantly pushed by automobile sector growth. The 1985–2003 oil glut even fueled the sales of low fuel economy vehicles in
OECD The Organisation for Economic Co-operation and Development (OECD; french: Organisation de coopération et de développement économiques, ''OCDE'') is an intergovernmental organisation with 38 member countries, founded in 1961 to stimulate e ...
countries. The 2008 economic crisis seems to have had some impact on the sales of such vehicles; still, in 2008 oil consumption showed a small increase. In 2016 Goldman Sachs predicted lower demand for oil due to emerging economies concerns, especially China. The
BRICS BRICS is an acronym for five leading emerging economies: Brazil, Russia, India, China, and South Africa. The first four were initially grouped as "BRIC" (or "the BRICs") in 2001 by Goldman Sachs economist Jim O'Neill, who coined the ter ...
(Brasil, Russia, India, China, South Africa) countries might also kick in, as China briefly had the largest automobile market in December 2009. In the long term, uncertainties linger; the
OPEC The Organization of the Petroleum Exporting Countries (OPEC, ) is a cartel of countries. Founded on 14 September 1960 in Baghdad by the first five members (Iran, Iraq, Kuwait, Saudi Arabia, and Venezuela), it has, since 1965, been headquart ...
believes that the OECD countries will push low consumption policies at some point in the future; when that happens, it will definitely curb oil sales, and both OPEC and the
Energy Information Administration The U.S. Energy Information Administration (EIA) is a principal agency of the U.S. Federal Statistical System responsible for collecting, analyzing, and disseminating energy information to promote sound policymaking, efficient markets, and publ ...
(EIA) kept lowering their 2020 consumption estimates during the past five years. A detailed review of
International Energy Agency The International Energy Agency (IEA) is a Paris-based autonomous intergovernmental organisation, established in 1974, that provides policy recommendations, analysis and data on the entire global energy sector, with a recent focus on curbing carb ...
oil projections have revealed that revisions of world oil production, price and investments have been motivated by a combination of demand and supply factors. All together, Non-OPEC conventional projections have been fairly stable the last 15 years, while downward revisions were mainly allocated to OPEC. Recent upward revisions are primarily a result of US
tight oil Tight oil (also known as shale oil, shale-hosted oil or light tight oil, abbreviated LTO) is light crude oil contained in unconventional petroleum-bearing formations of low permeability, often shale or tight sandstone. Economic production from ...
. Production will also face an increasingly complex situation; while OPEC countries still have large reserves at low production prices, newly found reservoirs often lead to higher prices; offshore giants such as Tupi, Guara and
Tiber The Tiber ( ; it, Tevere ; la, Tiberis) is the third-longest river in Italy and the longest in Central Italy, rising in the Apennine Mountains in Emilia-Romagna and flowing through Tuscany, Umbria, and Lazio, where it is joined by the Riv ...
demand high investments and ever-increasing technological abilities. Subsalt reservoirs such as Tupi were unknown in the twentieth century, mainly because the industry was unable to probe them.
Enhanced Oil Recovery Enhanced oil recovery (abbreviated EOR), also called tertiary recovery, is the extraction of crude oil from an oil field that cannot be extracted otherwise. EOR can extract 30% to 60% or more of a reservoir's oil, compared to 20% to 40% using ...
(EOR) techniques (example: Daqing Field, DaQing, China) will continue to play a major role in increasing the world's recoverable oil. The expected availability of petroleum resources has always been around 35 years or even less since the start of the modern exploration. The oil constant, an insider pun in the German industry, refers to that effect. A growing number of divestment campaigns from major funds pushed by newer generations who question the sustainability of petroleum may hinder the financing of future oil prospection and production.


Peak oil

Peak oil is a term applied to the projection that future petroleum production (whether for individual oil wells, entire oil fields, whole countries, or worldwide production) will eventually peak and then decline at a similar rate to the rate of increase before the peak as these reserves are exhausted. The peak of oil discoveries was in 1965, and oil production per year has surpassed oil discoveries every year since 1980. However, this does not mean that potential oil production has surpassed oil demand. It is difficult to predict the oil peak in any given region, due to the lack of knowledge and/or transparency in accounting of global oil reserves. Based on available production data, proponents have previously predicted the peak for the world to be in years 1989, 1995, or 1995–2000. Some of these predictions date from before the recession of the early 1980s, and the consequent lowering in global consumption, the effect of which was to delay the date of any peak by several years. Just as the 1971 U.S. peak in oil production was only clearly recognized after the fact, a peak in world production will be difficult to discern until production clearly drops off. In 2020, according to BP#Climate policy, BP's Energy Outlook 2020, peak oil had been reached, due to the changing energy landscape coupled with the Financial market impact of the COVID-19 pandemic#Oil prices, economic toll of the COVID-19 pandemic. While there has been much focus historically on peak oil supply, focus is increasingly shifting to peak demand as more countries seek to transition to renewable energy. The GeGaLo index of geopolitical gains and losses assesses how the geopolitical position of 156 countries may change if the world fully transitions to renewable energy resources. Former oil exporters are expected to lose power, while the positions of former oil importers and countries rich in renewable energy resources is expected to strengthen.


Unconventional oil

Unconventional oil] is petroleum produced or extracted using techniques other than the conventional methods. The calculus for peak oil has changed with the introduction of unconventional production methods. In particular, the combination of
horizontal drilling Directional drilling (or slant drilling) is the practice of drilling non-vertical bores. It can be broken down into four main groups: oilfield directional drilling, utility installation directional drilling, directional boring (horizontal dir ...
and
hydraulic fracturing Fracking (also known as hydraulic fracturing, hydrofracturing, or hydrofracking) is a well stimulation technique involving the fracturing of bedrock formations by a pressurized liquid. The process involves the high-pressure injection of "frack ...
has resulted in a significant increase in production from previously uneconomic plays. Analysts expected that $150 billion would be spent on further developing North American tight oil fields in 2015. The large increase in tight oil production is one of the reasons behind the price drop in late 2014. Certain rock strata contain hydrocarbons but have low permeability and are not thick from a vertical perspective. Conventional vertical wells would be unable to economically retrieve these hydrocarbons. Horizontal drilling, extending horizontally through the strata, permits the well to access a much greater volume of the strata. Hydraulic fracturing creates greater permeability and increases hydrocarbon flow to the wellbore.


Hydrocarbons on other worlds

On Saturn (planet), Saturn's largest moon, Titan (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. Drilled samples from the surface of Mars taken in 2015 by the Curiosity Rover, ''Curiosity'' rover's Mars Science Laboratory have found organic molecules of benzene and
propane Propane () is a three-carbon alkane with the molecular formula . It is a gas at standard temperature and pressure, but compressible to a transportable liquid. A by-product of natural gas processing and petroleum refining, it is commonly used a ...
in 3-billion-year-old rock samples in Gale Crater.


In fiction


See also

* Barrel of oil equivalent * Filling station * Gas oil ratio * List of oil exploration and production companies * List of oil fields * Manure-derived synthetic crude oil * Oil burden * Petroleum geology * Petroleum politics * Petrocurrency * Thermal depolymerization * Total petroleum hydrocarbon * Waste oil * Unconventional (oil & gas) reservoir


Citations


Explanatory footnotes


General and cited references

* * translated 1955 * * * * * * * Mirbabayev M.F.(2017).Brief history of the first drilled oil well;and the people involved.-"Oil-Industry History"(US),vol.18,#1, p. 25-34.


Further reading

* Antonia Juhasz, Juhasz, Antonia, "The End of OIL?: The COVID-19 pandemic, pandemic has battered an already struggling oil industry. Whether it survives is up to us", ''Sierra Magazine'', vol. 105, no. 5 (September / October 2020), pp. 36–40, 51. *


External links


Global Fossil Infrastructure Tracker

API – the trade association of the US oil industry.
(American Petroleum Institute)
U.S. Energy Information Administration
*

* [https://www.jodidata.org/ Joint Organisations Data Initiative , Oil and Gas Data Transparency]
U.S. National Library of Medicine: Hazardous Substances Databank – Crude Oil

Best Dubai Desert Safari Deals
*
A Short History of Petroleum
, Scientific American, 10 August 1878, p. 85 {{Authority control Petroleum, Causes of war Chemical mixtures Glassforming liquids and melts