Barrel (unit)
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A barrel is one of several
units of volume A unit of volume is a unit of measurement for measuring volume or capacity, the extent of an object or space in three dimensions. Units of capacity may be used to specify the volume of fluids or bulk goods, for example water, rice, sugar, grain o ...
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 are roughly double the volumes of others; volumes in common use range approximately from . In many connections the term is used almost interchangeably with ''barrel''. Since medieval times the term as a unit of measure has had various meanings throughout Europe, ranging from about 100 litres to about 1,000 litres. The name was derived in medieval times from the French , of unknown origin, but still in use, both in French and as derivations in many other languages such as
Italian Italian(s) may refer to: * Anything of, from, or related to the people of Italy over the centuries ** Italians, an ethnic group or simply a citizen of the Italian Republic or Italian Kingdom ** Italian language, a Romance language *** Regional Ita ...
,
Polish Polish may refer to: * Anything from or related to Poland, a country in Europe * Polish language * Poles Poles,, ; singular masculine: ''Polak'', singular feminine: ''Polka'' or Polish people, are a West Slavic nation and ethnic group, w ...
, and
Spanish Spanish might refer to: * Items from or related to Spain: **Spaniards are a nation and ethnic group indigenous to Spain **Spanish language, spoken in Spain and many Latin American countries **Spanish cuisine Other places * Spanish, Ontario, Can ...
. In most countries such usage is obsolescent, increasingly superseded by SI units. As a result, the meaning of corresponding words and related concepts (vat, cask, keg etc.) in other languages often refers to a physical container rather than a known measure. In the international oil market context, however, prices in
United States dollar The United States dollar ( symbol: $; code: USD; also abbreviated US$ or U.S. Dollar, to distinguish it from other dollar-denominated currencies; referred to as the dollar, U.S. dollar, American dollar, or colloquially buck) is the officia ...
s per barrel are commonly used, and the term is variously translated, often to derivations of the
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
/ Teutonic root ''fat'' (for example ''vat'' or ''Fass''). In other commercial connections, barrel sizes such as beer
keg A keg is a small barrel. Wooden kegs made by a cooper were used to transport nails, gunpowder, and a variety of liquids. A keg is normally now constructed of stainless steel, although aluminium can be used if it is coated with plastic on th ...
volumes also are standardised in many countries.


Dry goods in the US

* US dry barrel: **Defined as length of stave , diameter of head , distance between heads , circumference of bulge outside measurement; representing as nearly as possible 7,056 cubic inches; and the thickness of staves not greater than (diameter ≈ ). Any barrel that is 7,056 cubic inches is recognized as equivalent. This is exactly equal to . * US barrel for cranberries ** Defined as length of stave , diameter of head , distance between heads , circumference of bulge outside measurement; and the thickness of staves not greater than (diameter ≈ ). No equivalent in cubic inches is given in the statute, but later regulations specify it as 5,826 cubic inches. Some products have a standard weight or volume that constitutes a barrel: * Cornmeal, * Cement (including
Portland cement Portland cement is the most common type of cement in general use around the world as a basic ingredient of concrete, mortar, stucco, and non-specialty grout. It was developed from other types of hydraulic lime in England in the early 19th ...
), or * Sugar, * Wheat or rye flour, or *
Lime (mineral) Lime is a calcium-containing inorganic material composed primarily of oxides and hydroxide, usually calcium oxide and/or calcium hydroxide. It is also the name for calcium oxide which occurs as a product of coal-seam fires and in altered ...
, large barrel, or small barrel * Butter and cheese in UK, * Salt,


Fluid barrel in the US and UK

Fluid barrels vary depending on what is being measured and where. In the UK a beer barrel is . In the US most fluid barrels (apart from oil) are (half a hogshead), but a beer barrel is . The size of beer
keg A keg is a small barrel. Wooden kegs made by a cooper were used to transport nails, gunpowder, and a variety of liquids. A keg is normally now constructed of stainless steel, although aluminium can be used if it is coated with plastic on th ...
s in the US is based loosely on fractions of the US beer barrel. When referring to beer barrels or kegs in many countries, the term may be used for the commercial package units independent of actual volume, where common range for professional use is 20–60  L, typically a DIN or ''Euro keg'' of 50 L.


History

Richard III, King of England from 1483 until 1485, had defined the wine puncheon as a cask holding 84 gallons and a wine tierce as holding 42 gallons. Custom had made the 42 gallon watertight tierce a standard container for shipping eel, salmon, herring, molasses, wine, whale oil, and many other commodities in the English colonies by 1700. After the
American Revolution The American Revolution was an ideological and political revolution that occurred in British America between 1765 and 1791. The Americans in the Thirteen Colonies formed independent states that defeated the British in the American Revoluti ...
in 1776, American merchants continued to use the same size barrels.


Oil barrel

In the
oil 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 ...
, an oil barrel is defined as , or . Oil companies that are listed on American
stock exchanges A stock exchange, securities exchange, or bourse is an exchange where stockbrokers and traders can buy and sell securities, such as shares of stock, bonds and other financial instruments. Stock exchanges may also provide facilities for the ...
typically report their production in terms of volume and use the units bbl (one barrel), or kbbl or Mbbl (one kilobarrel, one thousand barrels), or MMbbl (one million barrels), and occasionally for wider comprehensive statistics Gbbl (or sometimes Gbl), for
giga Giga ( or ) is a unit prefix in the metric system denoting a factor of a short-scale billion or long-scale milliard (109 or ). It has the symbol G. ''Giga'' is derived from the Greek word (''gígas''), meaning "giant". The ''Oxford English Dic ...
-barrel (one
billion Billion is a word for a large number, and it has two distinct definitions: *1,000,000,000, i.e. one thousand million, or (ten to the ninth power), as defined on the short scale. This is its only current meaning in English. * 1,000,000,000,000, i. ...
barrels). There is a conflict concerning the units for oil barrels (see ). For all other
physical quantities A physical quantity is a physical property of a material or system that can be quantified by measurement. A physical quantity can be expressed as a ''value'', which is the algebraic multiplication of a ' Numerical value ' and a ' Unit '. For exam ...
, according to the International System of Units, the uppercase letter "M" means "
mega- Mega is a metric prefix, unit prefix in metric systems of units denoting a factor of one million (106 or 1000000 (number), ). It has the unit symbol M. It was confirmed for use in the International System of Units (SI) in 1960. ''Mega'' comes fro ...
" ("one million"), for example: MHz (one million
hertz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that o ...
, or megahertz), MW (one million
watt The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named after James ...
s, or megawatt), MeV (one million
electronvolt In physics, an electronvolt (symbol eV, also written electron-volt and electron volt) is the measure of an amount of kinetic energy gained by a single electron accelerating from rest through an electric potential difference of one volt in vacuum ...
, or megaelectronvolt). But due to tradition, the Mbbl acronym is used today meaning "one thousand bbl", as a heritage of the roman number "M" for Latin "mille" meaning "one thousand". On the other hand, there are efforts to avoid this ambiguity, and most of the barrel dealers today prefer to use kbbl, instead of Mbbl, mbbl, MMbbl or mmbbl. Outside the United States, volumes of oil are usually reported in cubic metres (m3) instead of oil barrels. Cubic metre is the basic volume unit in the International System. In Canada, oil companies measure oil in cubic metres, but convert to barrels on export, since most of Canada's oil production is exported to the US. The nominal conversion factor is 1 cubic metre = 6.2898 oil barrels, but conversion is generally done by
custody transfer Custody Transfer in the oil and gas industry refers to the transactions involving transporting physical substance from one operator to another. This includes the transferring of raw and refined petroleum between tanks and railway tank cars; onto s ...
meters on the border, since the volumes are specified at different temperatures, and the exact conversion factor depends on both density and temperature. Canadian companies operate internally and report to Canadian governments in cubic metres, but often convert to US barrels for the benefit of American investors and oil marketers. They generally quote prices in Canadian dollars per cubic metre to other Canadian companies, but use
US dollars The United States dollar (symbol: $; code: USD; also abbreviated US$ or U.S. Dollar, to distinguish it from other dollar-denominated currencies; referred to as the dollar, U.S. dollar, American dollar, or colloquially buck) is the official ...
per barrel in financial reports and press statements, making it appear to the outside world that they operate in barrels. Companies on the European stock exchanges report the ''mass'' of oil in
tonne The tonne ( or ; symbol: t) is a unit of mass equal to 1000  kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United State ...
s. Since different varieties of petroleum have different densities, however, there is not a single conversion between mass and volume. For example, one tonne of heavy distillates might occupy a volume of . In contrast, one tonne of crude oil might occupy , and one tonne of gasoline will require . Overall, the conversion is usually between per tonne.


History

The measurement of an "oil barrel" originated in the early
Pennsylvania Pennsylvania (; ( Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, ...
oil fields. The
Drake Well The Drake Well is a oil well in Cherrytree Township, Venango County in the U.S. state of Pennsylvania, the success of which sparked the first oil boom in the United States. The well is the centerpiece of the Drake Well Museum located south of ...
, the first oil well in the US, was drilled in Pennsylvania in 1859, and an oil boom followed in the 1860s. When oil production began, there was no standard container for oil, so oil and petroleum products were stored and transported in barrels of different shapes and sizes. Some of these barrels would originally have been used for other products, such as beer, fish, molasses, or turpentine. Both the barrels (based on the old English wine measure), the tierce (159 litres) and the
whiskey Whisky or whiskey is a type of distilled alcoholic beverage made from fermented grain mash. Various grains (which may be malted) are used for different varieties, including barley, corn, rye, and wheat. Whisky is typically aged in wooden ...
barrels were used. Also, barrels were in common use. The 40 gallon whiskey barrel was the most common size used by early oil producers, since they were readily available at the time. Around 1866, early oil producers in Pennsylvania came to the conclusion that shipping oil in a variety of different containers was causing buyer distrust. They decided they needed a standard unit of measure to convince buyers that they were getting a fair volume for their money, and settled on the standard wine tierce, which was two gallons larger than the standard whisky barrel. The ''Weekly Register'', an Oil City, Pennsylvania newspaper, stated on August 31, 1866 that "the oil producers have issued the following circular": And by that means, King Richard III's English wine tierce became the American standard oil barrel. By 1872, the standard oil barrel was firmly established as 42 US-gallons. The 42 gallon standard oil barrel was officially adopted by the Petroleum Producers Association in 1872 and by the U.S. Geological Survey and the U.S. Bureau of Mines in 1882. In modern times, many different types of oil, chemicals, and other products are transported in steel drums. In the United States, these commonly have a capacity of and are referred to as such. They are called 200 litre or 200 kg drums outside the United States. In the United Kingdom and its former dependencies, a drum was used, even though all those countries now officially use the metric system and the drums are filled to 200 litres. Thus, the 42 US-gallon oil barrel is a unit of measure, and is no longer a physical container used to transport crude oil, as most petroleum is moved in pipelines or
oil tanker 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 ...
s. In the United States, the 42 US-gallon size of barrel as a unit of measure is largely confined to the oil industry, while different sizes of barrel are used in other industries. Nearly all other countries use the
metric system The metric system is a system of measurement that succeeded the decimalised system based on the metre that had been introduced in France in the 1790s. The historical development of these systems culminated in the definition of the Interna ...
.


Definitions and units

The abbreviations Mbbl and MMbbl refer to one thousand and one million barrels respectively. These are derived from the Latin "mille", meaning "thousand". This is different from the SI convention for where "M" stands for "mega" representing million, from the Greek for "large". Outside of the oil industry, the unit Mbbl ( megabarrel) can sometimes stand for one million barrels. The "b" may have been doubled originally to indicate the plural (1 bl, 2 bbl), or possibly it was doubled to eliminate any confusion with bl as a symbol for the bale. Some sources assert that "bbl" originated as a symbol for "blue barrels" delivered by Standard Oil in its early days. However, while Ida Tarbell's 1904 Standard Oil Company history acknowledged the "holy blue barrel", the abbreviation "bbl" had been in use well before the 1859 birth of the U.S. petroleum industry.
Oil wells 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 ...
recover not just oil from the ground, but also
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 ...
and water. The term barrels of liquid per day (BLPD) refers to the total volume of liquid that is recovered. Similarly, barrels of oil equivalent or BOE is a value that accounts for both oil and natural gas while ignoring any water that is recovered. Other terms are used when discussing only oil. These terms can refer to either the production of crude oil at an oil well, the conversion of crude oil to other products at an
oil refinery 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, lique ...
, or the overall consumption of oil by a region or country. One common term is barrels per day (BPD, BOPD, bbl/d, bpd, bd, or b/d), where 1 BPD is equivalent to 0.0292 
gallons per minute The gallon is a unit of volume in imperial units and United States customary units. Three different versions are in current use: *the imperial gallon (imp gal), defined as , which is or was used in the United Kingdom, Ireland, Canada, Austral ...
. BP ''Statistical Review 2006''. One BPD also becomes 49.8 tonnes per year. At an oil refinery, production is sometimes reported as barrels per calendar day (b/cd or bcd), which is total production in a year divided by the days in that year. Likewise, barrels per stream day (BSD or BPSD) is the quantity of oil product produced by a single refining unit during continuous operation for 24 hours. Burning one tonne of light, synthetic, or heavy crude yields 38.51, 39.40, or 40.90 GJ (thermal) respectively (10.70, 10.94, or 11.36 MW·h), so 1 tonne per day of synthetic crude is about 456 kW of thermal power and 1 bpd of synthetic crude is about 378 kW (slightly less for light crude, slightly more for heavy crude).


Accuracy when converting from barrel to cubic metre

When used to denote a volume, one barrel is exactly 42 
US gallons The gallon is a unit of volume in imperial units and United States customary units. Three different versions are in current use: *the imperial gallon (imp gal), defined as , which is or was used in the United Kingdom, Ireland, Canada, Austr ...
and is easily converted to any other unit of volume. As the US gallon since 1893 is defined as 3.785411784 litre, a volume of one barrel is exactly 158.987294928 litres. Using the approximate value 159 litre is about 0.008% off. In the oil industry, following the definition of the
American Petroleum Institute The American Petroleum Institute (API) is the largest U.S. trade association for the oil and natural gas industry. It claims to represent nearly 600 corporations involved in production, refinement, distribution, and many other aspects of the ...
, a standard barrel of oil is often taken to mean the amount of oil that at a standard pressure and temperature would occupy a volume of exactly . This standard barrel of oil will occupy a different volume at different pressures and temperatures. A standard barrel in this context is thus not simply a measure of volume, but of volume under specific conditions. The task of converting this standard barrel of oil to a standard cubic metre of oil is complicated by the fact that the standard cubic metre is defined by the
American Petroleum Institute The American Petroleum Institute (API) is the largest U.S. trade association for the oil and natural gas industry. It claims to represent nearly 600 corporations involved in production, refinement, distribution, and many other aspects of the ...
to mean the amount of oil that at 101.325 
kPa KPA may refer to: * Keele Postgraduate Association, Keele University, UK, formerly Keele Research Association (KRA) * Kensington (Olympia) station, London, England, National Rail station code * Kenya Ports Authority * ''Kiln phosphoric acid'', a ...
and occupies 1 cubic metre. The fact that the conditions are not exactly the same means that an exact conversion is impossible unless the exact expansion coefficient of the crude is known, and this will vary from one crude oil to another. For a light oil with density of 850 kilogram per cubic metre (
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 ...
of 35),
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 ...
calculated from density_oil as API_g = (141.5 / SG ) − 131.5,
where SG is
specific gravity Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for liquids is nearly always measured with respect to water at its densest ...
= density_oil / density_water.
warming the oil from to might increase its volume by about 0.047%. Conversely, a heavy oil with a density of 934 kg/m3 (API gravity of 20) might only increase in volume by 0.039%. If physically measuring the density at a new temperature is not possible, then tables of
empirical data Empirical evidence for a proposition is evidence, i.e. what supports or counters this proposition, that is constituted by or accessible to sense experience or experimental procedure. Empirical evidence is of central importance to the sciences and ...
can be used to accurately predict the change in density. In turn, this allows maximum accuracy when converting between standard barrel and standard cubic metre. The logic above also implies the same level of accuracy in measurements for barrels if there is a error in measuring the temperature at time of measuring the volume. For ease of trading, communication and
financial accounting Financial accounting is the field of accounting concerned with the summary, analysis and reporting of financial transactions related to a business. This involves the preparation of financial statements available for public use. Stockholders, ...
, international commodity exchanges often set a conversion factor for benchmark crude oils. For instance the conversion factor set by the
New York Mercantile Exchange The New York Mercantile Exchange (NYMEX) is a commodity futures exchange owned and operated by CME Group of Chicago. NYMEX is located at One North End Avenue in Brookfield Place in the Battery Park City section of Manhattan, New York City. T ...
(NYMEX) for
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 Ceno ...
(WCS) crude oil traded at
Hardisty, Alberta Hardisty is a town in Flagstaff County in east-central Alberta, Canada. It is approximately from the Saskatchewan border, near the crossroads of Highway 13 and Highway 881, in the Battle River Valley. Hardisty is mainly known as a pivotal pet ...
, Canada is 6.29287 U.S. barrels per cubic metre, despite the uncertainty in converting the volume for crude oil. Regulatory authorities in producing countries set standards for measurement accuracy of produced hydrocarbons, where such measurements affect taxes or royalties to the government. In the United Kingdom, for instance, the measurement accuracy required is ±0.25%.


Qualifiers

A barrel can technically be used to specify any volume. Since the actual nature of the fluids being measured varies along the stream, sometimes qualifiers are used to clarify what is being specified. In the oil field, it is often important to differentiate between rates of production of fluids, which may be a mix of oil and water, and rates of production of the oil itself. If a well is producing 10 mbd of fluids with a 20% water cut, then the well would also be said to be producing 8,000 barrels of oil a day (bod). In other circumstances, it can be important to include
gas Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma). A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or ...
in production and consumption figures. Normally, gas amount is measured in
standard cubic feet A standard cubic foot (scf) is a unit used both in the natural gas industry to represent an amount of natural gas and in other industries where other gases are used. It is the unit commonly used when following the customary system, a collection ...
or cubic metres for volume (as well as in kg or
Btu The British thermal unit (BTU or Btu) is a unit of heat; it is defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. It is also part of the United States customary units. The modern SI u ...
, which don't depend on pressure or temperature). But when necessary, such volume is converted to a volume of oil of equivalent
enthalpy Enthalpy , a property of a thermodynamic system, is the sum of the system's internal energy and the product of its pressure and volume. It is a state function used in many measurements in chemical, biological, and physical systems at a constant ...
of combustion. Production and consumption using this analogue is stated in barrels of oil equivalent per day (boed). In the case of water-injection wells, in the United States it is common to refer to the injectivity rate in barrels of water per day (bwd). In Canada, it is measured in cubic metres per day (m3/d). In general, water injection rates will be stated in the same units as oil production rates, since the usual objective is to replace the volume of oil produced with a similar volume of water to maintain reservoir pressure.


See also

*
55 gallon drum A drum (also called a barrel) is a cylindrical shipping container used for shipping bulk cargo. Drums can be made of steel, dense paperboard (commonly called a fiber drum), or plastic, and are generally used for the transportation and storage of ...
* Barrel *
Barrel of oil equivalent The barrel of oil equivalent (BOE) is a unit of energy based on the approximate energy released by burning one barrel (, or ) of crude oil. The BOE is used by oil and gas companies in their financial statements as a way of combining oil and nat ...
*
English brewery cask units Capacities of brewery casks were formerly measured and standardised according to a specific system of English units. The system was originally based on the ale gallon of . In United Kingdom and its colonies, with the adoption of the imperial system ...
*
English wine cask units Capacities of wine casks were formerly measured and standardised according to a specific system of English units. The various units were historically defined in terms of the wine gallon so varied according to the definition of the gallon until the ...
*
Imperial units The imperial system of units, imperial system or imperial units (also known as British Imperial or Exchequer Standards of 1826) is the system of units first defined in the British Weights and Measures Act 1824 and continued to be developed th ...
*
List of unusual units of measurement An unusual unit of measurement is a unit of measurement that does not form part of a coherent system of measurement, especially because its exact quantity may not be well known or because it may be an inconvenient multiple or fraction of a base ...
*
Petroleum 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 crud ...
* Petroleum pricing around the world * Standard Barrel Act For Fruits, Vegetables, and Dry Commodities * United States customary units *
Units of measurement A unit of measurement is a definite magnitude of a quantity, defined and adopted by convention or by law, that is used as a standard for measurement of the same kind of quantity. Any other quantity of that kind can be expressed as a multi ...


Notes


References

{{DEFAULTSORT:Barrel (unit) Brewing Customary units of measurement in the United States Imperial units Petroleum Units of volume Alcohol measurement