Products of Crude Oil Refining

Products of crude oil refining includes liquefied petroleum gases, pentanes plus, aviation gasoline, motor gasoline, naphtha-type jet fuel, kerosene-type jet fuel, kerosene, distillate fuel oil, residual fuel oil, petrochemical feedstock, special naphtha, lubricants, waxes, petroleum coke, asphalt, road oil, still gas, and miscellaneous products. Actually, product of crude oil refining can be grouped according to the way crude oil is distilled and separated into fractions. These includes light distillates (Liquid petroleum gas (LPG), Gasoline (also known as petrol), Kerosene, Jet fuel and other aircraft fuel.), middle distillates (Automotive and rail-road diesel fuels, Residential heating fuel, other light fuel oils) and heavy distillate (Heavy fuel oils, Bunker fuel oil and other residual fuel oils)

Now let’s look at each of the products of crude oil refining:

Motor Gasoline (Finished)

A complex mixture of relatively volatile hydrocarbons with or without small quantities of additives, blended to form a fuel suitable for use in spark-ignition engines. Motor gasoline, as defined in ASTM Specification D 4814 or Federal Specification VV-G-1690C, is characterized as having a boiling range of 122 to 158 degrees Fahrenheit at the 10 percent recovery point to 365 to 374 degrees Fahrenheit at the 90 percent recovery point. “Motor Gasoline” includes conventional gasoline; all types of oxygenated gasoline, including gasohol; and reformulated gasoline, but excludes aviation gasoline.

Aviation Gasoline (Finished)

A complex mixture of relatively volatile hydrocarbons with or without small quantities of additives, blended to form a fuel suitable for use in aviation reciprocating engines. Fuel specifications are provided in ASTM Specification D 910 and Military Specification MIL-G-5572. Note: Data on blending components are not counted in data on finished aviation gasoline.

Diesel Fuel

A light distillate fuel oil that has a distillation temperature of 550 degrees Fahrenheit at the 90-percent recovery point and meets the specifications defined in ASTM Specification D 975. It is used in high speed diesel engines generally operated under frequent speed and load changes, such as those in city buses and similar vehicles.

Fuel Oil

A light distillate fuel oil that has distillation temperatures of 400 degrees Fahrenheit at the 10-percent recovery point and 550 degrees Fahrenheit at the 90-percent recovery point and meets the specifications defined in ASTM Specification D 396. It is used primarily as fuel for portable outdoor stoves and portable outdoor heaters.

No. 2 Diesel Fuel

A distillate fuel oil that has a distillation temperature of 640 degrees Fahrenheit at the 90-percent recovery point and meets the specifications defined in ASTM Specification D 975. It is used in high-speed diesel engines that are generally operated under uniform speed and load conditions, such as those in railroad locomotives, trucks, and automobiles.

Fuel Oil (Heating Oil)

A distillate fuel oil that has a distillation temperature of 640 degrees Fahrenheit at the 90-percent recovery point and meets the specifications defined in ASTM Specification D 396. It is used in atomizing type burners for domestic heating or for moderate capacity commercial/industrial burner units.

No. 4 Fuel

A distillate fuel oil made by blending distillate fuel oil and residual fuel oil stocks. It conforms to ASTM Specification D 396 or Federal Specification VV-F-815C and is used extensively in industrial plants and in commercial burner installations that are not equipped with preheating facilities. It also includes No. 4 diesel fuel used for low- and medium-speed diesel engines and conforms to ASTM Specification D 975.

Gas Oil

A liquid petroleum distillate having a viscosity intermediates between that of kerosene and lubricating oil. It derives its name from having originally been used in the manufacture of illuminating gas. It is now used to produce distillate fuel oils and gasoline.

Gasohol

A blend of finished motor gasoline containing alcohol (generally ethanol but sometimes methanol) at a concentration of 10 percent or less by volume. Data on gasohol that has at least 2.7 percent oxygen, by weight, and is intended for sale inside carbon monoxide nonattainment areas are included in data on oxygenated gasoline.

Heavy Gas Oil

Petroleum distillates with approximates boiling ranges from 651 degrees Fahrenheit to 1000 degrees Fahrenheit.

High-Sulfur Distillate Fuel Oil

Distillates fuel oil having sulfur content greater than 500 ppm.

Kerosene

A light petroleum distillate that is used in space heaters, cook stoves, and water heaters and is suitable for use as a light source when burned in wick-fed lamps. Kerosene has a maximum distillation temperature of 400 degrees Fahrenheit at the 10-percent recovery point, a final boiling point of 572 degrees Fahrenheit, and a minimum flash point of 100 degrees Fahrenheit. Included are No. 1-K and No. 2-K, the two grades recognized by ASTM Specification D 3699 as well as all other grades of kerosene called range or stove oil, which have properties similar to those of No. 1 fuel oil.

Kerosene-Type Jet Fuel

A kerosene-based product having a maximum distillation temperature of 400 degrees Fahrenheit at the 10-percent recovery point and a final maximum boiling point of 572 degrees Fahrenheit and meeting ASTM Specification D 1655 and Military Specifications MIL-T-5624P and MIL-T-83133D (Grades JP-5 and JP-8). It is used for commercial and military turbojet and turboprop aircraft engines.

Commercial Kerosene-type jet fuel intended for use in commercial aircraft.

Military Kerosene-type jet fuel intended for use in military aircraft.

Lease Condensate.

A mixture consisting primarily of pentanes and heavier hydrocarbons which is recovered as a liquid from natural gas in lease separation facilities. This category excludes natural gas liquids, such as butane and propane, which are recovered at downstream natural gas processing plants or facilities.

Light Gas Oils

Liquid Petroleum distillates heavier than naphtha, with approximates boiling ranges from 401 degrees Fahrenheit to 650 degrees Fahrenheit.

Benzene (C₆H₆)

An aromatic hydrocarbon present in small proportion in some crude oils and made commercially from petroleum by the catalytic reforming of naphthenes in petroleum naphtha. Also made from coal in the manufacture of coke. Used as a solvent, in manufacturing detergents, synthetic fibers, and petrochemicals and as a component of high-octane gasoline.

Asphalt

A dark-brown-to-black cement-like material containing bitumens as the predominant constituent obtained by petroleum processing; used primarily for road construction. It includes crude asphalt as well as the following finished products: cements, fluxes, the asphalt content of emulsions (exclusive of water), and petroleum distillates blended with asphalt to make cutback asphalts.

Lubricants

Substances used to reduce friction between bearing surfaces or as process materials either incorporated into other materials used as processing aids in the manufacture of other products, or used as carriers of other materials. Petroleum lubricants may be produced either from distillates or residues. Lubricants include all grades of lubricating oils from spindle oil to cylinder oil and those used in greases.

Wax

A solid or semi-solid material at 77 degrees Fahrenheit consisting of a mixture of hydrocarbons obtained or derived from petroleum fractions, or through a Fischer-Tropsch type process, in which the straight-chained paraffin series predominates. This includes all marketable wax, whether crude or refined, with a congealing point (ASTM D 938) between 80 (or 85) and 240 degrees Fahrenheit and a maximum oil content (ASTM D 3235) of 50 weight percent.

Xylene (C₆H₄(CH₃)₂)

Colorless liquid of the aromatic group of hydrocarbons made the catalytic reforming of certain naphthenic petroleum fractions. Used as high-octane motor and aviation gasoline blending agents, solvents, chemical intermediates. Isomers are metaxylene, orthoxylene, paraxylene.

Liquefied Petroleum Gases (LPG)

A group of hydrocarbon-based gases derived from crude oil refining or natural gas fractionation. They include: ethane, ethylene, propane, propylene, normal butane, butylene, isobutane, and isobutylene. For convenience of transportation, these gases are liquefied through pressurization.

Liquefied Refinery Gases (LRG)

Liquefied petroleum gases fractionated from refinery or still gases. Through compression and/or refrigeration, they are retained in the liquid state. The reported categories are ethane/ethylene, propane/propylene, normal butane/butylene, and isobutane/isobutylene. Exclude still gas.

Low-Sulfur Distillate Fuel Oil

Distillate fuel oil having sulfur contents greater than 15 ppm to 500 ppm. Low sulfur distillate fuel oil also includes product with sulfur content equal to or less than 15 ppm if the product is intended for pipeline shipment and the pipeline has a sulfur specification below 15 ppm.

Miscellaneous Products

Includes all finished products not classified elsewhere (e.g., petrolatum, lube refining byproducts (aromatic extracts and tars), absorption oils, ram-jet fuel, petroleum rocket fuels, synthetic natural gas feedstock, and specialty oils). Note: Beginning with January 2004 data, naphtha-type jet fuel is included in Miscellaneous Products.

Distillation of Crude Oil

Distillation of crude oil is the first step in the refining of crude. It involves the separation of the crude oil into fractions and these fractions are mixtures containing hydrocarbon compounds whose boiling points lie within a specified range. Looking at it this way, because crude oil is a mixture of hydrocarbons with different boiling temperatures, it can be separated by distillation into groups of hydrocarbons that boil between specific boiling points.

Atmospheric distillation and vacuum distillation are two types of crude oil distillation performed in a refinery. Let’s look at how each of the distillation is performed:

Atmospheric Distillation of Crude Oil

This takes place in a distilling column at or near atmospheric pressure. The crude oil is heated to about 350 - 400^oC and the vapor and liquid are piped into the distilling column. The liquid falls to the bottom and the vapor rises, passing through a series of perforated trays (sieve trays). Heavier hydrocarbons condense more quickly and settle on lower trays and lighter hydrocarbons remain as a vapor longer and condense on higher trays. 

Liquid fractions are drawn from the trays and removed. In this way the light gases, methane, ethane, propane and butane pass out the top of the column, petrol is formed in the top trays, kerosene and gas oils in the middle, and fuel oils at the bottom. Residue drawn of the bottom may be burned as fuel, processed into lubricating oils, waxes and bitumen or used as feedstock for cracking units.

Vacuum Distillation of Crude Oil

To recover additional heavy distillates from crude oil residue, it may be piped to a second distillation column where the process is repeated under vacuum, called vacuum distillation. This allows heavy hydrocarbons with boiling points of 450^oC and higher to be separated without them partly cracking into unwanted products such as coke and gas. The heavy distillates recovered by vacuum distillation can be converted into lubricating oils by a variety of processes. The most common of these is called solvent extraction. 

In one version of this process the heavy distillate is washed with a liquid which does not dissolve in it but which dissolves (and so extracts) the non-lubricating oil components out of it. Another version uses a liquid which does not dissolve in it but which causes the non-lubricating oil components to precipitate (as an extract) from it.

Other processes exist which remove impurities by adsorption onto a highly porous solid or which remove any waxes that may be present by causing them to crystallize and precipitate out.

End-product of Crude Oil Distillation

End-product of crude oil distillation may be grouped into light distillates, middle distillates and heavy distillates. Now let’s look at each of them:

Light Distillates

• Liquid petroleum gas (LPG)
• Gasoline (also known as petrol)
• Kerosene
• Jet fuel

Middle Distillates

• Diesel fuels
• Residential heating fuel
• Other light fuel oils

Heavy Distillates

• Heavy fuel oils
• Bunker fuel oil and other residual fuel oils

Crude Oil Refining Process

Crude oil refining process are the processes (chemical and other facilities) used in oil refineries to transform crude oil into useful petroleum products. Each refinery has its own unique arrangement and combination of refining processes largely determined by the refinery location, desired products and economic considerations. There are most probably no two refineries that are identical in every respect but each refinery maintain basic processing units. Hence in studying crude oil refining process, we will be looking at the processing units used in crude oil refineries and basic process of each unit.

Here are basic crude oil refining processing units and processes employed by each unit:

Crude Oil Distillation Unit (CDU)

In crude oil refining process, the distillation unit in crude oil refinery distill and separate valuable distillates (naphtha, kerosene, diesel) and atmospheric gas oil (AGO) from the crude feedstock.

Processes

• Desalt and dehydrate the crude using electrostatic enhanced liquid/liquid separator (Desalter).
• Heat the crude to the desired temperature using fired heaters.
• Flash the crude in the atmospheric distillation column.
• Utilize pumparound cooling loops to create internal liquid reflux.
• Product draws are on the top, sides, and bottom

Vacuum Distillation Unit (VDU)

The next step in crude oil refining process involves the vacuum distillation unit of the refinery. The objective of this unit is to recover valuable gas oil from reduced crude via vacuum distillation.

Processes

• Heat the reduced crude to the desired temperature using fired heaters
• Flash the reduced crude in the vacuum distillation column
• Utilize pumparound cooling loops to create internal liquid reflux
• Product draws are top, sides, and bottom

Delayed Coking Process

                              

The next step in crude oil refining process is the delayed coking process. The objective is to convert low value residue to valuable products such as naphtha and diesel.

Processes

• Preheat residue feed and provide primary condensing of coke drum vapors by introducing the feed to the bottom of the main fractionators
• Heat the coke drum feed by fired heaters
• Flash superheated feed in a large coke drum where the coke remains and vapors leave the top and goes back to the fractionator
• Off-line coke drum is drilled and the petroleum coke is removed via Hydrojetting

Fluidic Coking Process

Another step in crude oil refining process is fluidic coking process. The objective of this process is to convert low value residue to valuable products like naphtha, diesel and coker gas oil.

Process

• Preheat residue feed, scrub coke particles, and provide primary condensing of reactor vapors by introducing the feed to the scrubber
• Residue is atomized into a fluid coke bed and thermocracking occurs on the particle surface
• Coke particles leaving the reactor are steam stripped to remove remaining liquid hydrocarbons
• Substoichiometric air is introduced to burner to burn some of the coke and provide the necessary heat for the reactor
• Reactor vapors leave the scrubber and go to the fractionators

Fluid Catalytic Cracking (FCC) Unit

                    

Another crude oil refinery process is carried out in the fluid catalytic unit with the objective to convert low value gas oils to valuable products like naphtha, diesel and slurry oil.

Process

• Gas oil feed is dispersed into the bottom of the riser using steam
• Thermal cracking occurs on the surface of the catalyst
• Disengaging drum separates spent catalyst from product vapors
• Steam strips residue hydrocarbons from spent catalyst
• Air burns away the carbon film from the catalyst in either a “partial-burn” or “full-burn” mode of operation
• Regenerated catalyst enters bottom of riser-reactor

HF Alkylation Process

Another important crude oil refinery process is the HF Alkylation process. Its objective is to combine light olefins like propylene and butylenes with isobutene to form a high octane gasoline (alkylate).

Process

• Olefins from FCC are combined with IsoButane and fed to the HF Reactor where alkylation occurs
• Acid settler separates the free HF from the hydrocarbons and recycles the acid back to the reactor
• A portion of the HF is regenerated to remove acid oils formed by feed contaminants or hydrocarbon polymerization
• Hydrocarbons from settler go to the DeIsobutanizer for fractionating the propane and isobutane from the n-butane and alkylate
• Propane is then fractionated from the isobutane; propane as a product and the isobutane to be recycled to the reactor
• N-Butane and alkylate are deflourinated in a bed of solid adsorbent and fractionated as separate products

Hydrotreating Process

Another crude oil refining process is the hydrotreating process. The objective is to remove contaminants like sulfur, nitrogen, metals and saturate olefins and aromatics to produce a clean product for further processing or finished product sales.

Process

• Feed is preheated using the reactor effluent
• Hydrogen is combined with the feed and heated to the desired hydrotreating temperature using a fired heater
• Feed and hydrogen pass downward in a hydrogenation reactor packed with various types of catalyst depending upon reactions desired
• Reactor effluent is cooled and enters the high pressure separator which separates the liquid hydrocarbon from the hydrogen/hydrogen sulfide/ammonia gas
• Acid gases are absorbed from the hydrogen in the amine absorber
• Hydrogen, minus purges, is recycled with make-up hydrogen
• Further separation of LPG gases occurs in the low pressure separator prior tosending the hydrocarbon liquids to fractionation

Hydrocracking Process

Hydrocracking process is crude oil refining process aimed to remove feed contaminants like nitrogen, sulfur, metals and to convert low value gas oils to valuable products like naphtha, middle distillates, and ultra-clean lube base stocks.

Process

• Preheated feed is mixed with hot hydrogen and passes through a multi-bed reactor with interstage hydrogen quenches for hydrotreating
• Hydrotreated feed is mixed with additional hot hydrogen and passes through a multi-bed reactor with quenches for first pass hydrocracking
• Reactor effluents are combined and pass through high and low pressure separators and are fed to the fractionator where valuable products are drawn from the top, sides, and bottom
• Fractionator bottoms may be recycled to a second pass hydrocracker for additional conversion all the way up to full conversion

Catalytic Reforming Process

Another crude oil refining process is the catalytic reforming process with an objective to convert low-octane naphtha into a high-octane reformate for gasoline blending and/or to provide aromatics like benzene, toluene, and xylene for petrochemical plants. Reforming also produces high purity hydrogen for hydrotreating processes.

Process

• Naphtha feed and recycle hydrogen are mixed, heated and sent through successive reactor beds
• Each pass requires heat input to drive the reactions
• Final pass effluent is separated with the hydrogen being recycled or purged for hydrotreating
• Reformate product can be further processed to separate aromatic components or be used for gasoline blending

Isomerization Process

Isomerization process is another crude oil refining process used to convert low-octane n-paraffins to high-octane iso-paraffins.

Process

• Desulfurized feed and hydrogen are dried in fixed beds of solid dessicant prior to mixing together
• The mixed feed is heated and passes through a hydrogenation reactor to saturate olefins to paraffins and saturate benzene
• The hydrogenation effluent is cooled and passes through a isomerization reactor
• The final effluent is cooled and separated as hydrogen and LPGs which typically go to fuel gas, and isomerate product for gasoline blending

Crude Oil Refinery

Crude Oil Refinery

Crude oil refinery is an organized and coordinated arrangement of manufacturing processes designed to produce physical and chemical changes in crude oil to convert it to everyday useful products such as petrol, diesel, kerosene, aviation fuel, bitumen refinery gas and sulfur. A typical crude oil refinery processes about a hundred thousand to several hundred thousand barrels of crude oil a day. Because of the high capacity, many of the refinery units operate continuously in a steady state or nearly steady state for months to years.

Actually, crude oil in its natural form contains a mixture of hydrocarbons and relative small quantities of other materials which are removed and the oil broken down to its various components. The steps involved in a typical refinery are the separation process, the conversion process and the purification process. Now, let’s briefly look at how these processes are carried out in a crude oil refinery:

The Separation Process in a Crude Oil Refinery

The crude oil is first separated by boiling points into six main grades of hydrocarbons: refinery gas (used for refinery fuel), gasoline (naphthas), kerosene, light and heavy gas oils and long residue. This initial separation is done by distillation. The long residue is further separated in the butane desaphalting unit, and some of these components (such as the refinery gas) are further separated with chemical reactions and by using solvents which dissolve one component of a mixture significantly better than another.

The Conversion Process in a Crude Oil Refinery

Of the crude oils separated out from the original crude (refinery gas, gasoline, kerosene, light and heavy gasoils and asphalt), only refinery gas can be used as is, all the others require some further treatment before they can be made into the final product. This firstly involves the removal of sulfur (as it interferes with the success of some later later processes) and then the chemical conversion of the oils into more desirable compounds. For example, naphthas are "reformed" from paraffins and naphthenes into aromatics. The chemical equilibria are also manipulated to ensure a maximum yield of the desired product.

The Purification Process in a Crude Oil Refinery

The crude oil has now been separated into refinery gas, hydrogen sulfide, naphtha, kerosene, gas oil, asphalt and bitumen. Two more processes have to be carried out, on the naphtha and the hydrogen sulfide respectively, before the hydrocarbons are ready for blending into saleable products. Some refinery plants also manufactures its own hydrogen and purifies its own effluent water. This water purification, along with gas 'scrubbing' to remove undesirable compounds from the gases to be discharged into the atmosphere, ensures that the refinery has minimal environmental impact.

Common Process Units Found in a Refinery

Desalter Unit

Removes salt from the crude oil before it enters the atmospheric distillation unit.

Atmospheric Distillation Unit

Distill crude oil into fractions.

Vacuum Distillation Unit

Further distills residual bottoms after atmospheric distillation.

Naphtha Hydrotreater Unit

Uses hydrogen to desulfurize naphtha from atmospheric distillation and must hydrotreat the naphtha before sending to a Catalytic Reformer unit.

Catalytic Reformer Unit

Used to convert the naphtha-boiling range molecules into higher octane reformate (reformer product). The reformate has higher content of aromatics and cyclic hydrocarbons). An important byproduct of a reformer is hydrogen released during the catalyst reaction. The hydrogen is used either in the hydrotreaters or the hydrocracker.

Distillate Hydrotreater Unit

Removes sulfur from distillates (such as diesel) after atmospheric distillation.

Fluid Catalytic Cracker (FCC) Unit

Upgrade heavier fractions into lighter, more valuable products.

Hydrocracker unit

Use hydrogen to upgrade heavier fractions into lighter, more valuable products.

Visbreaking unit

Upgrade heavy residual oils by thermally cracking them into lighter, more valuable reduced viscosity products.

Merox Unit

Treat LPG, kerosene or jet fuel by oxidizing mercaptans to organic disulfides.

Coking Units

Process very heavy residual oils into gasoline and diesel fuel, leaving petroleum coke as a residual product.

Alkylation unit

Produce high-octane component for gasoline blending.

Dimerization Unit

Convert olefins into higher-octane gasoline blending components.

Isomerization unit

Converts linear molecules to higher-octane branched molecules for blending into gasoline or feed to alkylation units.

Steam Reforming Unit

Produce hydrogen for the hydrotreaters or hydrocracker.

Liquified Gas Storage Vessels

Stores propane and similar gaseous fuels at pressure sufficient to maintain them in liquid form. These are usually spherical vessels or "bullets" (i.e., horizontal vessels with rounded ends).

Storage Tanks

Store crude oil and finished products, usually cylindrical, with some sort of vapor emission control and surrounded by an earthen berm to contain spills.

Claus Unit

Convert hydrogen sulfide from hydrodesulfurization into elemental sulfur.

Utility Units

Such as cooling towers circulate cooling water, boiler plants generates steam, and instrument air systems include pneumatically operated control valves and an electrical substation.

Wastewater Collection and Treating Systems

Consist of API separators, dissolved air flotation (DAF) units and further treatment units such as an activated sludge biotreater to make water suitable for reuse or for disposal.

Solvent Refining Units

Use solvent such as cresol or furfural to remove unwanted, mainly aromatics from lubricating oil stock or diesel stock.

Solvent Dewaxing Units

Remove the heavy waxy constituents petrolatum from vacuum distillation products.

Let’s look at environmental impact of crude oil refineries:

Crude Oil Refinery and the Environment

Air, water and land can all be affected by refinery operations. The refining process releases a number of different chemicals into the atmosphere and a notable odor normally accompanies the presence of a refinery. Aside from air pollution impacts there are also wastewater concerns, risks of industrial accidents such as fire and explosion, and noise health effects due to industrial noise.

Many governments worldwide have mandated restrictions on contaminants that refineries release, and most refineries have installed the equipment needed to comply with the requirements of the pertinent environmental protection regulatory agencies. Crude oil refinery environmental and safety concerns mean that oil refineries are sometimes located some distance away from major urban areas.

Crude Oil Reserves

The amount of technically and economically recoverable crude oil is known as crude oil reserves. This may be reserve for an oil well, an oil reservoir, an oil field, a nation or for the world. Hence we refer to a particular oil well reserve, a field’s crude oil reserve, a country’s crude oil reserve and world crude oil reserve. The actual recoverable oil from crude oil reserves are more or less related to their degree of certainty. I mean… considering limitations in extraction techniques, only a fraction of crude oil reserves can be brought to surface.

Now, let’s look at different terms associated with crude oil reserves:

Crude oil proven reserve

Proven crude oil reserves are those crude reserves with reasonable certainty… at least 90% confidence of being recoverable under available economical, political and existing technological conditions. Proven reserves can further be classified as proven developed and proven undeveloped reserves. Proven developed reserves… as the name suggest are reserves that can be produced with existing wells and perforations, or from additional reservoirs where minimal operating expense is required while proven undeveloped reserves require additional capital investment to bring the oil to the surface.

Crude oil unproven reserves

Crude oil unproven reserves are those crude reserves with technical, contractual or regulatory uncertainties. Usually, unproven reserves are used internally by oil companies and government agencies for future planning purposes but are not routinely complied. Like proven reserves, unproven reserves also can be classified as probable and possible. Probable reserves are attributed to known accumulations and claim a 50% confidence level of recovery while possible reserves are attributed to known accumulations that have a less likely chance of being recovered than probable reserves. This term is often used for reserves which are claimed to have at least a 10% certainty of being produced.

Strategic Crude Oil Reserve

Strategic crude oil reserves are generally not counted when computing a nation’s crude oil reserve. It refers to government-controlled crude oil reserves for both economic and national security reasons. For example, United States Energy Information Administration states that approximately 4.1 billion barrels (650,000,000 m³) of oil are held in strategic reserves, of which 1.4 billion is government-controlled (m³=cubic meters).

Crude Oil Reserve Recovery Factor

Crude oil reserve recovery factor is the ratio of producible oil reserves to total oil in place for a given field. It varies greatly among oil fields and the recovery factor of any particular field may change over time based on operating history and in response to changes in technology and economics. The recovery factor may also rise over time if additional investment is made in enhanced oil recovery techniques such as gas injection, surfactants injection, water-flooding, or microbial enhanced oil recovery.

Crude Oil Reserve Growth

Crude oil reserve growth is a situation where most early estimates of the reserves of an oil field are conservative and tend to grow with time. This is because the geology of the subsurface cannot be examined directly and as such indirect techniques must be used to estimate the size and recoverability of the resource and while new technologies have increased the accuracy of these techniques, significant uncertainties still remain.

Estimated world crude oil reserves

Summary of Top 17 Proven World Crude Oil Reserve Data 2012

Country	Reserves 109 bbl
Venezuela	296.5
Saudi Arabia	265.4
Canada	175
Iran	151.2
Iraq	143.1
Kuwait	101.5
United Arab Emirates	136.7
Russia	74.2
Kazakhstan	49
Libya	47
Nigeria	37
Qatar	25.41
China	20.35
United States	20.35
Angola	13.5
Algeria	13.42
Brazil	13.2