History of Crude Oil

History of crude oil can be traced to the first oil wells drilled in China in the 4^th century. They have depths of up to about 243 meters deep and were drilled using bits attached to bamboo poles. The oil was mainly used in salt production by burning it to evaporate salt-water to produce salt. However, crude oil current status as integral component of politics, society, and technology has its roots in the early 20^th century with the invention of internal combustion engine.

Now, let’s look at early and modern history of crude oil in detail:

Early history of crude oil

Early history of crude oil can be traced to more than four thousand years ago. Looking at it, it was believed that asphalt (product of crude oil) was employed in the construction of the walls and towers of ancient city of Babylon. Also, ancient Persian tablets indicate the medicinal and lighting uses crude oil in the upper levels of their society.

The ancient records of Asian countries are said to contain many reference to the use of natural gas for lighting and heating purposes. Around 7^th century, crude oil was known as burning water in Japan. It is also on record that streets of ancient Baghdad were paved with tar (product of crude oil) gotten from natural fields in the region. 9^th century Azerbaijan was not left out as it was also on record that oil fields were exploited in the area with production estimated as hundreds of shiploads.

Crude oil distillation became available in Western Europe by the 12^th century through Islamic Spain. Also, crude oil recorded as pacura has been present in Romania since the 13^th century.

The earlier history of crude oil in Americas was in 1858 when James Miller Williams in Oil Springs, Ontario, Canada dug the first commercial oil well. This followed with the discovery of crude oil in 1859, near Titusville, Pennsylvania. The industry grew slowly in the 1800s, driven by the demand for kerosene and oil lamps.

Modern history of crude oil

The modern history of crude oil can be traced to the 19^th century growth in demand for petroleum as a fuel for lighting in North America and around the world. It actually began with the process to distill kerosene from crude oil. Looking at it, it all started in 1847 when James Young noticed a natural seepage in Ridding colliery at Alfreton, Derbyshire from which he distilled light thin oil suitable for use as lamp oil, and at the same time obtaining thicker oil suitable for lubricating machinery. He subsequently set up a small business refining the crude oil in 1848.

The subsequent increase in demand for refined petroleum prompted considerable search for crude oil. Looking at it, an early commercial well was hand dug in Poland in 1853 and another in nearby Romania in 1857. At around the same time the world's first, small, oil refinery was opened at Jasło in Poland, with a larger one opened at Ploiesti in Romania shortly after. In 1857, Romania became the first country in the world to have had crude oil output officially recorded at 275 tonnes.

The first most modern crude oil well was drilled near Titusville, Pennsylvania by Edwin Drake in 1859. However, it is on record that the first commercial oil well in Canada became operational in 1858 at Oil Spring, Ontario. Actually, the discovery at Oil Springs started an oil boom which brought hundreds of investors 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. After an explosion of natural gas in Canada on January 16, 1862 its first oil gusher came into production shooting into the air at a recorded rate of 3,000 barrels per day. By the end of the 19th century the Russian Empire, particularly the Branobel company in Azerbaijan, had taken the lead in production. Oil exploration in North America during the early 20th century later led to the U.S. becoming the leading producer by mid-century. As petroleum production in the U.S. peaked during the 1960s, however, the United States was surpassed by Saudi Arabia and the Soviet Union.

In essence, history of crude oil can first be traced to 7000 years of trying to find its uses, the period it was known to burn well than other source of oil to the 19^th century discovery of modern drilling technology which led to commercial production and other large scale uses of refined crude oil products.

Crude Oil Production Process

Crude oil production process involves operations that bring crude oil to the surface for further processing. Here we will be looking at exploration, extraction and recovering processes involved in crude oil production.  First, let’s look at the exploration process:

Exploration Processes

The first step involved in crude oil production process is exploration where geologists use seismic surveys and other methods to search for geological structures that may form oil reservoirs. As of 2010, no method has proven 100 percent effective in helping geologists locate crude oil deposits. The best, and most profitable, technique oil explorers’ use is seismic exploration.

“Classic” and “passive” methods are used in seismic surveys. The “classic” method includes making an underground explosion nearby and observing the seismic response that provides information about the geological structures under the ground while “passive” method involves extracting information from naturally-occurring seismic waves.

However, in most recent seismic exploration, a satellite or mobile seismic device shoots radio waves at prospective crude oil sites and then sends that data to a supercomputer which creates a digital model of the environment based on that data

Other instruments such as magnetometers and gravimeters are also sometimes used in crude oil exploration.

Extraction Processes

The second step involved in crude oil production process is extraction which normally starts with drilling wells into the underground reservoir. However, while the first drilling technique stuck a pipe straight into the ground, modern drillers now have slant drilling techniques. In general, slant drilling proves much more beneficial than vertical drilling. Slanted pumps are curved, allowing them to rotate 360 degrees and reach several different deposits from the same location.

Oil extraction also occurs at sea using the same methods as land-based oil extraction, but requires special types of platforms because the ocean floor may not support the weight of a normal rig or the size of a solid platform proves to costly to reach ocean depths. Most offshore operations tether a floating platform connected to cables attached to the ocean floor. Those drilling in shallow water or those who have found a large deposit might want to install a permanent structure. Movable rigs, such a ship or a barge, are good for finding oil deposits and gathering oil from several smaller sites.

Generally, when an oil well has been tapped, a geologist will note its presence. The mixtures of oil, gas and water from the well is separated on the surface. The water is disposed of and the oil and gas are treated, measured, and tested.

Recovering Processes

The third and final step involved in crude oil production process is recovering which include bringing the crude oil and associated gas to the surface, maintaining production, and purifying, measuring, and testing. Three stages are involved in crude oil recovering: Primary recovery stage, secondary recovery stage and tertiary recovery stage.

Now, let’s look at each of the recovery stages:

Primary recovery method of crude oil production process

Reservoir drive comes from a number of natural mechanisms during the primary recovery stage. These include: natural water displacing oil downward into the well, expansion of the natural gas at the top of the reservoir, expansion of gas initially dissolved in the crude oil, and gravity drainage resulting from the movement of oil within the reservoir from the upper to the lower parts where the wells are located. Typically, 5-15% recovery factor are achieved during the primary recovery stage.

Secondary recovery method of crude oil production process

With diminishes in natural reservoir drive, secondary recovery methods are applied. They rely on replacing or increasing the natural reservoir drive with an artificial drive by the supply of external energy into the reservoir in the form of form of injecting fluid to increase reservoir pressure. This is achieved by water injection, natural gas reinjection and gas lift, which injects air, carbon dioxide or some other gas into the bottom of an active well, reducing the overall density of fluid in the wellbore. Typically, 35-45 recovery factors are achieved after primary and secondary recovery operations.

Tertiary Recovery method of crude oil production process

When secondary oil recovery isn’t enough for adequate crude oil recovery, tertiary recovery methods are applied, though when cost effective. This involves increase in the mobility of the crude oil in other to increase extraction. Different techniques are used in tertiary recovery methods which include:

·         First is the thermally enhanced oil recovery technique (TEOR). This is a tertiary recovery technique that involves heating the oil, thus reducing its viscosity and making it easier to extract. Steam injection is the most common form of TEOR, and is often done when a gas turbine is used to generate electricity and the waste heat is used to produce steam, which is then injected into the reservoir. In-situ burning is another form of TEOR, but instead of steam, some of the oil is burned to heat the surrounding oil.

·         Another method used to reduce viscosity is through carbon dioxide flooding.

·         Microbial treatments are another tertiary recovery method. Special blends of the microbes are used to treat and break down the hydrocarbon chain in oil thus making the oil easy to recover as well as being more economic versus other conventional methods.

Typically, tertiary recovery allows another 35%-45% of the reservoir’s oil to be recovered.

In essence, crude oil production process involves exploration, extraction and recovering of crude oil.

Crude Oil Production

Crude oil production involves the processes of exploration or location of oil filed, drilling and extraction of the crude. Now, let’s briefly look at each of the processes involve in crude oil production:

Exploration of crude oil

Geologist use seismic surveys to explore crude oil.  Seismic survey is used to search for geological structures that may form oil reservoirs. This can be done by two methods known as ‘classic’ and ‘passive’ method. The classic method include making an underground explosion nearby and observing the seismic response that provides information about the geological structures under the ground while passive methods involves extracting information from naturally-occurring seismic waves.

Other instruments such as gravimeters and magnetometers are also used to explore crude oil.

Drilling Crude oil wells

After exploration and discovery of crude oil, the next step in crude oil production is drilling wells into the underground reservoir. Drilling crew sets up and start the drilling operations and this is done by first, from the starter hole, they drill a surface hole down to a pre-set depth, somewhere the oil trap is located.

Once the pre-set depth is reached, they must place casing-pipe sections into the hole to prevent it from collapsing in on itself. The casing pipe has spacers around the outside to keep it centered in the hole. The crew completes the well to allow oil to flow into the casing in a controlled manner once the have reached the final depth. Finally, a collection of valves called a “Christmas Tree” is fitted to the top to regulate pressure and control flows.

Extraction of crude oil

Once the crude oil is flowing, the next step in crude oil production is to remove the oil rig from site and set up production equipment to extract the oil from the well. This is done by placing a pump at the well head. The pump system comprises a gear box driven by an electric motor to move a lever. The lever pushes and pulls a polishing rod up and down. The polishing rod is attached to a sucker rod, which is attached to a pump. This system forces the pump up and down, creating a suction that draws oil up through the well.

In cases where the oil is too heavy to flow, a second hole is drilled into the reservoir and steam is injected under pressure. The heat from the steam thins the oil in the reservoir, and the pressure helps push it up the well. This process is called enhanced oil recovery.

The amount of oil that is recoverable is determined by a number of factors including the permeability of the rocks, the strength of natural drives (the gas present, pressure from adjacent water or gravity), and the viscosity of the oil. When the reservoir rocks are "tight" such as shale, oil generally cannot flow through but when they are permeable such as in sandstone, oil flows freely. The flow of oil is often helped by natural pressures surrounding the reservoir rocks including natural gas that may be dissolved in the oil, natural gas present above the oil, water below the oil and the strength of gravity. 

Oils tend to span a large range of viscosity from liquids as light as gasoline to heavy as tar. The lightest forms tend to result in higher extraction rates.

Crude Oil Exploration

Crude oil exploration involves geological studies and technical examination to detect the presence of crude oil. To determine the location for crude oil exploration, various geology surveys such as magnetic survey, seismic reflection survey and gravity survey are carried out first. At a more complex stage, elaborate seismic surveys are conducted to measure the time taken by sound waves to travel through matter. After confirming the presence of crude oil, exploration activities will now commence.

Let’s look at different method of crude oil exploration:

Ancient methods of crude oil exploration

Digging or drilling near known oil and gas seeps constitutes earlier methods of crude oil exploration. There are cases of accidental finds while drilling for water. Also, because of abundant seeps, guesswork and good luck were sufficient for finding oil. Earlier geologist used geological hunches and knowledge of existing seeps and petroleum residue in soil samples collected from near a gas spring to promote drilling for oil. Generally speaking, oil companies held the use of geology in low regard till the advent of geophysical methods of crude oil exploration.

Geophysical methods used in crude oil exploration

Geophysical methods of oil exploration enhanced the oil prospector’s knowledge of subterranean strata and it demonstrates an advantage for finding crude oil. Tools used were fairly basic and depended on fundamental variables in the earth's physical condition: gravity change, magnetic field change, time change, and electrical resistance. 

Example is Eoetvoes's torsion balance. Instruments like Eoetvoes’s torsion balance made use of the earth's gravitational field and the way the field varied according to differences in mass distribution near the earth's surface. Looking at it, because the density of rocks varies, the gravitational force they exert necessarily varies. If very light rocks are found close to the surface, the gravitational force they exert will be less than those of very heavy rocks. With this in mind, geophysicists attempted to locate oil-bearing structure which will be associated with minimum gravity by using the torsion balance instrument.

Another variation of gravity tool used in geophysical method of crude oil exploration is the pendulum method. This method relied on the period of a pendulum's oscillation adjusted by variations in gravity due to changes in altitude and latitude. The pendulum method was superseded by the gravity meter. Advances in gravity instrument technology afforded geophysicists better equipment with which to make more accurate determinations. 

The most common gravitational instrument in use today is the gravity meter or gravimeter, which measures variations in the earth's gravitational field by the gravitational pull on a mass balanced against some form of elastic force.

Magnetic Methods used in crude oil exploration

Another method of crude oil exploration is the Magnetic method. Most oil occurs in sedimentary rocks that are nonmagnetic. Igneous and metamorphic rocks rarely contain oil and are highly magnetized. By conducting a magnetic survey over a given area, a prospector can determine where oil-bearing sedimentary rock is more likely to be found.

Two types of magnetic instruments are used to measure the slight difference in magnetism in rocks, the field balance and the airborne magnetometer. The field balance is used on the earth's surface to measure magnetism in specific locations. The airborne magnetometer is used to measure the magnitude of the earth's total magnetic field over a large area.

Seismic Method of crude oil exploration

Another method of crude oil exploration is the seismic method. The central physical property upon which seismic crude oil prospecting is established is the variation in speed of the transmission of elastic earth waves or sound waves through different geological structures measured by time. 

There are two principle seismic methods: refraction and reflection.

Refraction prospecting consists of elastic earth waves, initiated by some concussive force, traveling down to a dense or high velocity bed, then being carried along that bed until they are refracted up to seismic detector locations on the surface some distance from the shot point. What is recorded is the time required for the sound wave to reach each detector location from the shot point. The speed of transmission of the waves through different geological structures is proportional to the density or compactness of the formation. Unconsolidated formations such as sands and shale’s transmit waves with a low velocity, weak sandstones and limestone’s with higher speeds, and massive crystalline rocks such as limestone, rock salt, schist, and various igneous rocks with very high speeds.

The refraction method aided petroleum explorers in locating salt domes that transmitted elastic earth waves at high rates of speed.

Stratigraphic Method of crude oil exploration

A final method of crude oil exploration is the study of stratigraphy. Stratigraphic exploration consists of establishing correlations between wells, matching fossils, strata, rock hardness or softness, and electrical and radioactivity data to determine the origin, composition, distribution, and succession of rock strata. Sample logs, driller's logs, time logs, electrical logs, radioactivity logs, and acoustic logs help geologists predict where oil bearing strata occur. Sample logs, compiled from well cuttings and cores, are used to identify key beds and lithologic sequences.

A core is a narrow column of rock that is taken from the top to the bottom of a well and shows rock in sequential order as it appears in the ground. Core samples also provide information on porosity, permeability, and saturation of rock in the well. Cuttings are not a continuous record like core samples, but provide a means for identifying sections within larger thick layers through fossil and mineral deposits. 

The driller's log provides basic information to the stratigrapher concerning depth, type of rock, density, fluids, and other miscellaneous data. The driller's log keeps track of the time required to drill through various strata and the recognition of key beds he drills through. This data is correlated with other information to enhance the chance of finding oil.

Early electrical methods of exploration tested electrical resistivity and electro-magnetic potential. Occurrences of oil and gas can be located by this difference in resistance. The most useful application of electric testing has been in the development and impact of well logging. Schlumberger electric well logging is now standard in the industry. These logs record the conductivity of interstitial water in rock, the movement of drilling mud into porous strata, and the movement of formation water into the well bore.

Radioactivity Logs, which record both gamma-ray and neutron values, have been in use productively since 1941. Because radioactivity can be measured with precision it can be used to identify different layers within beds. Radioactivity logs give an indication of the type of rocks and fluids contained in those rocks.

Acoustic or sonic logs are used to measure the porosity of a formation. This tool measures the speed at which an acoustic or sonic impulse is carried through a specified length of rock. The speed of sound through the rock gives an indication of the porosity and can be helpful in locating reservoirs.

Maps, including contour, isopach, cross sections, and three dimensional computer images, also aid the petroleum explorer in locating oil and gas. Contour maps give details of subsurface structural features enabling geologists to visualize three dimensional structures. Contour maps include information about porosity, permeability, and structural arrangements such as faults, pinch-outs, salt domes, and old shorelines. Isopatch maps show variations in thickness of a given subsurface formation and are used in calculating the size of reservoirs and secondary recovery operations. A cross section map is a diagram of an imaginary vertical cut along a straight line that reveals subterranean features of a given area much like looking at a road cut. Three dimensional computer maps construct images of subterranean strata as deep as thirty miles.

Formation of crude oil

Formation of crude oil can be credited to dead organisms. Over the years, the organisms decayed in the sedimentary layers. In these layers, there was little or no oxygen present. So microorganisms broke the remains into carbon-rich compounds that formed organic layers. The organic material mixed with the sediments, forming fine-grained shale, or source rock. As new sedimentary layers were deposited, they exerted intense pressure and heat on the source rock. The heat and pressure distilled the organic material into crude oil and natural gas.

The oil flowed from the source rock and accumulated in thicker, more porous limestone or sandstone, called reservoir rock. Movements in the Earth trapped the oil and natural gas in the reservoir rocks between layers of impermeable rock, or cap rock, such as granite or marble.

Let’s look closely at organic and chemical formation of crude oil:

Organic formation of crude oil

Crude oil is formed through the heating and compression of organic materials over a long period of time. It is widely believed that most of the oil we extract today comes from the remains of prehistoric plants and animal whose remains settled on the bottom of an Ocean or Lake. Over time this organic material combined with mud and was then heated to high temperatures from the pressure created by heavy layers of sediment.

For instance, there were certain warm nutrient-rich environments where the large amounts of organic material falling to the ocean floor exceeded the rate at which it could decompose. This resulted in large masses of organic material being buried under subsequent deposits such as shale formed from mud. This massive organic deposit later became heated and transformed under pressure into oil.

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, and above the maximum temperature the oil is converted to natural gas through the process of thermal cracking. Sometimes, oil formed at extreme depths may migrate and become trapped at a much shallower level.

Chemical formation of crude oil

In a more detail explanation of chemical formation of crude oil, it is widely believed that Formation of crude oil occurs from hydrocarbon pyrolysis in a variety of mainly endothermic reactions at high temperature and/or pressure. Looking at it, bacterial decomposition of the plants and animals removed most of the oxygen, nitrogen, phosphorus and sulfur from the matter, leaving behind a sludge made up mainly of carbon and hydrogen. As the oxygen was removed from the detritus, decomposition slowed. 

Over time the remains became covered by layers upon layers of sand and silt. As the depth of the sediment reached or exceeded 10,000 feet, pressure and heat changed the remaining compounds into the hydrocarbons and other organic compounds that form crude oil and natural gas.

The type of petroleum formed by the plankton layer depended largely on how much pressure and heat were applied. Low temperatures (caused by lower pressure) resulted in a thick material, such as asphalt. Higher temperatures produced lighter crude oil. Ongoing heat could produce gas, though if the temperature exceeded 500°F, the organic matter was destroyed and neither oil nor gas was produced.

Formation of crude oil reservoir

Conditions necessary for the formation of crude oil reservoirs are a source rock rich in hydrocarbon material buried deep enough for subterranean heat to cook it into oil; a porous and permeable reservoir rock for it to accumulate in; and a cap rock (seal) or other mechanism that prevents it from escaping to the surface.

Within these reservoirs, fluids will typically organize themselves like a three-layer cake with a layer of water below the oil layer and a layer of gas above it, although the different layers vary in size between reservoirs. Because most hydrocarbons are less dense than rock or water, they often migrate upward through adjacent rock layers until either reaching the surface or becoming trapped within porous rocks (known as reservoirs) by impermeable rocks above.

However, the process is influenced by underground water flows, causing oil to migrate hundreds of kilometers horizontally or even short distances downward before becoming trapped in a reservoir. When hydrocarbons are concentrated in a trap, an oil field forms, from which the liquid can be extracted by drilling and pumping.

Composition of Crude Oil

Crude oil is composed of hydrocarbons, organic compounds and small amounts of metal. However, hydrocarbons are the primary components of crude oil and hydrocarbon composition in crude oil can vary from 50%-97% depending on the type of crude oil and how it is extracted. Organic compounds like nitrogen, oxygen, and sulfur typically make-up between 6%-10% of crude oil while metals such as copper, nickel, vanadium and iron account for less than 1% of the total composition.

The hydrocarbons in crude oil are mostly alkanes, cycloalkanes and various aromatic hydrocarbons while the other organic compounds contain nitrogen, oxygen and sulfur, and trace amounts of metals such as iron, nickel, copper and vanadium. The exact molecular composition varies widely from formation to formation but the proportion of chemical elements vary over fairly narrow limits.

Although it is often called "black gold," crude oil has ranging viscosity and can vary in color to various shades of black and yellow depending on its hydrocarbon composition. Distillation, the process by which oil is heated and separated in different components, is the first stage in refining.

Let’s look at composition of heavy and light crude oil:

Composition of Heavy Crude Oil

Heavy oil is asphaltic and contains asphaltenes and resins. It is "heavy" (dense and viscous) due to the high ratio of aromatics and naphthenes to linear alkanes and high amounts of NSO's (nitrogen, sulfur, oxygen and heavy metals). Heavy oil has a higher percentage of compounds with over 60 carbon atoms and hence a high boiling point and molecular weight.

There are two main types of heavy crude oil:

·         Those that have over 1% sulfur (high sulfur crude oils), with aromatics and asphaltenes, and these are mostly found in North America (Canada (Alberta, Saskatchewan), United States (California), Mexico), South America (Venezuela, Colombia and Ecuador) and the Middle East (Kuwait, Saudi Arabia).

·          Those that have less than 1% sulfur (low sulfur crude oils), with aromatics,  naphthenes and resins, and these are mostly found in Western Africa (Chad), Central Africa(Angola) and East Africa (Madagascar).

Composition of Light crude

Light crude oil contains small amounts of hydroge  sulfide and carbon dioxide. It has low viscosity, low specific gravity and high API gravity due to the presence of a high proportion of light hydrocarbon fractions. It generally has a low wax content as well.

By Products of Crude Oil

By products of crude oil are useful materials derived from crude oil as it is processed in crude oil refinery. Determining which products to produce from a barrel of crude is based on daily and weekly market projections of the demand and market-clearing price for each petroleum product that a refinery could possibly make. Refineries must produce products which meet a variety of quality specifications and must respond to seasonal swings in both product demand and quality. Also, the relative quantities of petroleum products produced by a refinery (its "product slate") depend on the complexity of the refinery processes, the market demand and the properties of the crude being refined.

For example, most crude are processed into various grades of fuel oil and gasoline which can further be processed to produce jet fuel, diesel fuel, heating oil. Less volatile (Heavier) fractions can also be used to produce asphalt, tar, paraffin, wax, lubricating and other heavy oils. Chemicals used in petrochemical industries are also major by product of crude oil.

Here are different by products of crude oil:

Gaseous Fuel

Gaseous fuel includes ethane, liquefied petroleum gas (LPG) and refinery gas:

• Ethane is a straight-chain hydro-carbon (C₂H₆) natural gas.
•  Liquefied petroleum gasses (LPG) comprise of propane (C₃H₈) and butane (C₄H₁₀). They are the light hydrocarbon fraction of the paraffin series, derived from refinery processes, crude oil stabilization plants and natural gas processing plants. LPG is normally liquefied under pressure for transportation and storage.
•  Refinery gas is a non-condensable gas obtained during distillation of crude oil or treatment of oil products (e.g. cracking) in refineries. It consists mainly of hydrogen, methane, ethane and olefins. It also includes gases which are returned from the petrochemical industry. Refinery gas production refers to gross production.

Liquid Fuels

Liquid fuels include motor gasoline, gas diesel oil, aviation fuel, kerosene and jet fuel:

•  Motor gasoline is also known as premium motor spirit (PMS). It is light hydrocarbon oil used in internal combustion engines such as motor vehicles. Motor gasoline is distilled between 35°C and 215°C and is used as a fuel for land based spark ignition engines. It may include include additives, oxygenates and octane enhancers, including lead compounds such as TEL (Tetraethyl lead) and TML (tetramethyl lead)
• Gas diesel oil is also known as automotive gas oil (AGO) Gas oils are obtained from the lowest fraction from atmospheric distillation of crude oil, while heavy gas oils are obtained by vacuum redistillation of the residual from atmospheric distillation. Gas diesel oil distils between 180°C and 380°C. Several grades are available depending on uses: diesel oil for diesel compression ignition (cars, trucks, marine, etc.), light heating oil for industrial and commercial uses, and other gas oil including heavy gas oils which distil between 380°C and 540°C and which are used as petrochemical feedstocks.
• Aviation fuel also known as aviation gasoline is motor spirit prepared especially for aviation piston engines, with an octane number suited to the engine, a freezing point of -60°C, and a distillation range usually within the limits of 30°C and 180°C.
• Kerosene comprises refined petroleum distillate intermediate in volatility between gasoline and gas diesel oil. It is a medium oil distilling between 150°C and 300°C.
• Jet fuel comprises both gasoline and kerosene type jet fuels meeting specifications for use in aviation turbine power units.

Lubricants

Lubricants are hydrocarbons produced from distillate or residue; they are mainly used to reduce friction between bearing surfaces. This category includes all finished grades of lubricating oil, from spindle oil to cylinder oil, and those used in greases, including motor oils and all grades of lubricating oil base stocks.

Bitumen

Bitumen is obtained by vacuum distillation of oil residues from atmospheric distillation of crude oil. Bitumen is often referred to as asphalt and is primarily used for surfacing of roads and for roofing material. This category includes fluid and cut back bitumen.

Wax (Paraffin)

Waxes are saturated aliphatic hydrocarbons. They are residues extracted when dewaxing lubricant oils and they have a crystalline structure which is more or less fine according to the grade. Their main characteristics are that they are colourless, odourless and translucent, with a melting point above 45°C.

Petroleum coke

This is a black solid residue, obtained mainly by cracking and carbonizing of petroleum feedstock, vacuum bottoms, tar and pitches in processes such as delayed coking or fluid coking. It consists mainly of carbon (90 to 95 per cent) and has a low ash content. It is used as a feedstock in coke ovens for the steel industry, for heating purposes, for electrode manufacture and for production of chemicals.

Petrochemical feedstock

These are organic compounds used as ingredients for the chemical industry, ranging from polymers and pharmaceuticals.

Naphtha

Naphtha comprises material that distils between 30°C and 210°C.  They are used in petrochemical industry (e.g. ethylene manufacture or aromatics production) or for gasoline production by reforming or isomerisation within the refinery.

Here are summary of crude oil (petroleum) by products:

Crude oil by product	Blends	Usage
Gases	Still gases	Fuel gas
	Propane/butane	Liquefied petroleum gas (LPG)
Light/heavy naphtha	Motor fuel	Gasoline
	Aviation turbine, Jet-B	Jet fuel (naphtha type)
Kerosine	Aviation turbine, Jet-A	Jet fuel (kerosene type)
	No. 1 fuel oil	Kerosene (range oil)
Light gas oil	Diesel	Auto and tractor diesel
	No. 2 fuel oil	Home heating oil
Heavy gas oil	No. 4 fuel oil	Commercial heating oil
	No. 5 fuel oil	Industrial heating oil
	Bright stock	Lubricants
Residuals	No. 6 fuel oil	Bunker C oil
	Heavy residual	Asphalt
	Coke	Coke

Barrel of Crude Oil

Barrel of crude oil (bbl) is a unit volume of crude oil whose definition has not been universally standardized. In the United States and Canada, a barrel of crude oil is defined as 42 US gallons, which is equivalent to 158.987294928 liters exactly or approximately 34.9723 imperial gallons. Depending on the context, it can also be defined as 35 imperial gallons or as 159 liters. Oil companies typically report their production in terms of volume and use the units of bbl, Mbbl (one thousand barrels), or MMbbl (one million barrels).

History of crude oil measurement in barrels

The name barrel comes from medieval French baril. Measurement of crude oil in barrels can be traced to early Pennsylvania state oil fields. Reports had it that at the onset of oil production in early 1860s there was no standard container for crude oil, hence crude oil were stored and transported in barrels of different shapes and sizes. Shipment in variety of different containers caused distrust among buyers hence the introduction of a more standardized form of 42 US gallons.

In recent times, the 42 US gallon crude oil barrel is a unit of measure, as opposed to earlier physical container used to transport crude oil, as most petroleum is moved in pipelines or oil tankers. In the United States, the 55-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. Many oil-producing countries still use the American oil barrel.

Definitions and units of crude oil Barrel

The abbreviations Mbbl and MMbbl used to measure crude oil barrels refer to one thousand and one million barrels, respectively. The term barrels per day (BPD, BOPD, bbl/d, bpd, bd, or b/d) where 1 BPD is equivalent to 0.0292 gallons per minute. One BPD also becomes 49.8 tonnes per year. At an oil refinery, production is sometimes reported as barrels per calendar day (bc/d 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. Lastly, the terms mbd and mmbd are sometimes used to denote one thousand or one million barrels per day, respectively.

Conversion of Crude oil barrel

The litres in crude oil barrel are 159 litres which is equal to 35 imperial gallon and 42 US gallons. Since 1 barrel = exactly 42 American gallons, and 3.785431178 liters = 1 gallon, then. 42 x 3.78 = 158.987 liters = 1 barrel. One barrel of crude oil contains fourty two gallons. Once it is refined fourty two gallons of crude oil will produce fourty four gallons of finished product.

Because of the density of oil changes with temperature, however, the above conversion is not exactly correct. Since some countries use imperial unit while others use SI units, the American Petroleum Institute adopted two different methods for reporting the volume of oil. If volume is to be reported in bbl, then the volume will be measured at 14.696 psi and 60 °F. Likewise, the conditions are 101.325 kPa and 15 °C (or in some cases 20 °C) if the volume will be reported in m³. However, it is noteworthy that bbl and m³ are not exactly comparable. While the pressures of 14.696 psi and 101.325 kPa are exactly equivalent, the temperature 60 °F is equivalent to 15.56 °C. Since the measurement for m³ uses 15.00 °C instead of 15.56 °C, this difference will lead to a small error when converting between bbl and m³.

In addition, the magnitude of this error also depends on the type of oil. For a light oil with an API gravity of 35, warming the oil from 15.00 °C to 60.00 °F (which is 15.56 °C) might increase its volume by about 0.047%. Conversely, a heavy oil with an 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 can be used to accurately predict the change in density. In turn, this allows maximum accuracy when converting between bbl and m³.