Glossary

Acid Catalyst:
a catalyst having acidic character, for example aluminas
Acid Deposition:
acid rain; a form of pollution depletion in which pollutants, such as nitrogen oxides and sulfur oxides, are transferred from the atmosphere to soil or water; often referred to as atmospheric self-cleaning. The pollutants usually arise from the use of fossil fuels.
Acidity:
the capacity of an acid to neutralize a base, such as a hydroxyl ion (OH−)
Acidizing:
a technique for improving the permeability (q.v.) of a reservoir by injecting acid
Acid Number:
a measure of the reactivity of petroleum with a caustic solution given in terms of milligrams of potassium hydroxide that are neutralized by 1 g of petroleum
Acid Rain:
the precipitation phenomenon that incorporates anthropogenic acids and other acidic chemicals from the atmosphere to the land and water (see acid deposition)
Activation Energy (Ea):
the energy that is needed by a molecule or molecular complex to encourage reactivity to form products
Additive:
a material added to another (usually in small amounts) to enhance desirable properties or to suppress undesirable properties
Adsorption:
transfer of a substance from a solution to the surface of a solid resulting in relatively high concentration of the substance at the place of contact; see also chromatographic adsorption
Air Pollution:
the discharge of toxic gases and particulate matter introduced into the atmosphere, principally as a result of human activity
Air Sweetening:
a process in which air or oxygen is used to oxidize lead mercaptide to disulfides instead of using elemental sulfur
Alcohol:
the family name of a group of organic chemical compounds composed of carbon, hydrogen, and oxygen. The series of molecules vary in chain length and are composed of a hydrocarbon plus a hydroxyl group, CH3(CH2)nOH (e.g., methanol, ethanol, and tertiary butyl alcohol)
Alicyclic Hydrocarbon:
a compound containing carbon and hydrogen only, which has a cyclic structure (e.g., cyclohexane); also, collectively called naphthenes
Aliphatic Hydrocarbon:
a compound containing carbon and hydrogen only, which has an open-chain structure (e.g., as ethane, butane, octane, or butene) or a cyclic structure (e.g., cyclohexane)
Alkalinity:
the capacity of a base to neutralize the hydrogen ion (H+)
Alkali Treatment:
see caustic wash
Alkali Wash:
see caustic wash
Alkanes:
hydrocarbons that contain only single carbon–hydrogen bonds. The chemical name indicates the number of carbon atoms and ends with the suffix “-ane.”
Alkenes:
hydrocarbons that contain carbon–carbon double bonds. The chemical name indicates the number of carbon atoms and ends with the suffix “-ene.”
Alkylate:
the product of an alkylation (q.v.) process
Alkylate Bottoms:
residual from fractionation of alkylate; the alkylate product that boils higher than the aviation gasoline range; sometimes called heavy alkylate or alkylate polymer
Alkylation:
in the petroleum industry, a process by which an olefin (e.g., ethylene) is combined with a branched-chain hydrocarbon (e.g., isobutane); alkylation may be accomplished as a thermal or as a catalytic reaction
Alkyl Groups:
a group of carbon and hydrogen atoms that branch from the main carbon chain or ring in a hydrocarbon molecule. The simplest alkyl group, a methyl group, is a carbon atom attached to three hydrogen atoms.
Alumina (Al2O3):
used in separation methods as an adsorbent and in refining as a catalyst
ASTM International (formerly American Society for Testing and Materials):
the official organization in the United States for designing standard tests for petroleum and other industrial products
Analysis:
determining the properties of a feedstock before refining; inspection (q.v.) of feedstock properties
Aniline Point:
the temperature, usually expressed in °F, above which equal volumes of a petroleum product are completely miscible; a qualitative indication of the relative proportions of paraffins in a petroleum product that are miscible with aniline only at higher temperatures; a high aniline point indicates low aromatics
API (American Petroleum Institute) Gravity:
a measure of the lightness or heaviness of petroleum that is related to density and specific gravity
API = (141.5/sp gr at 60°F) – 131.5
Apparent Bulk Density:
the density of a catalyst as measured; usually loosely compacted in a container
Apparent Viscosity:
the viscosity of a fluid or several fluids flowing simultaneously measured in a porous medium (rock) and subject to both viscosity and permeability effects; also called effective viscosity
Aromatics:
a group of hydrocarbons of which benzene is the parent; named because many of their derivatives have sweet or aromatic odors
Aromatization:
the conversion of nonaromatic hydrocarbons to aromatic hydrocarbons by (1) rearrangement of aliphatic (noncyclic) hydrocarbons (q.v.) into aromatic ring structures and (2) dehydrogenation of alicyclic hydrocarbons (naphthenes)
Asphalt:
highly viscous liquid or semisolid composed of bitumen and present in most crudes; can be separated from other crude components by fractional distillation; used primarily for road paving and roofing shingles
Asphaltene Constituents:
molecular species that occur within the asphaltene fraction and that vary in polarity (functional group content) and molecular weight
Asphaltene Fraction:
the fraction of petroleum, heavy oil, or bitumen that is precipitated when a large excess (40 vol) of a low-boiling liquid hydrocarbon (e.g., pentane or heptane) is added to (1 vol of) the feedstock; usually a dark brown to black amorphous solid that does not melt before decomposition and is soluble in benzene or aromatic naphtha or other chlorinated hydrocarbon solvents
Asphaltic Constituents:
a general term usually meaning the asphaltene fraction plus the resin fraction
Associated Gas:
natural gas that is in contact with and/or dissolved in the crude oil of the reservoir. It may be classified as gas cap (free gas) or gas in solution (dissolved gas)
Associated Gas in Solution (or dissolved gas):
natural gas dissolved in the crude oil of the reservoir, under prevailing pressure and temperature conditions
Associated Molecular Weight:
the molecular weight of asphaltenes in an associating (nonpolar) solvent, such as toluene
Atmospheric Distillation:
distillation at atmospheric pressure; the refining process of separating crude oil components at atmospheric pressure by heating to temperatures of about 600-750°F (depending on the nature of the crude oil and desired products) and subsequent condensing of the fractions by cooling
Barrel:
the unit of measurement of liquids in the petroleum industry; the traditional measurement for crude oil volume: 1 barrel is equivalent to 42 US gallons (159 L) and 6.29 barrels is equivalent to 1 m3 of oil
Barrel of Oil Equivalent:
a unit of energy based on the approximate energy released by burning 1 barrel of crude oil
Base Number:
the quantity of acid expressed in milligrams of potassium hydroxide per gram of sample that is required to titrate a sample to a specified end point
Basic Nitrogen:
nitrogen (in petroleum) that occurs in pyridine form
Bentonite:
montmorillonite (a magnesium–aluminum silicate); used as a treating agent
Benzene:
a colorless aromatic liquid hydrocarbon (C6H6); 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 the manufacture of detergents, synthetic fibers, petrochemicals, and as a component of high-octane gasoline
Billion:
1 × 109.
Bioaccumulation (or bioconcentration):
the tendency of substances to accumulate in the body of organisms; the net uptake from their diet, respiration, or transfer across skin and loss due to excretion or metabolism. The bioaccumulation factor (BAF) or bioconcentration factor (BCF) is the ratio of concentrations in tissue to concentrations in a source, i.e., water or diet.
Bioavailability (or biological availability):
compound that is in a physical or chemical form that can be assimilated by a living organism; also the proportion of a chemical in an environmental compartment (e.g., water) that can be taken up by an organism
Biocide:
any chemical capable of killing bacteria and bioorganisms
Biodegradation:
a natural process of microbial transformation of chemicals, such as oil, under aerobic or anaerobic conditions; oil biodegradation usually requires nutrients, such as nitrogen and phosphorus; transformation may be complete producing water, carbon dioxide, and/or methane or incomplete, producing partially-oxidized chemicals
Biogenic:
material derived from bacterial or vegetation sources
Biological Lipid:
any biological fluid that is miscible with a nonpolar solvent. These materials include waxes, essential oils, chlorophyll, etc.
Biological Oxidation:
the oxidative consumption of organic matter by bacteria by which organic matter is converted into gases
Biomass:
biological organic matter; materials produced from the processing of wood, corn, sugar, and other agricultural waste or municipal waste. It can be converted to syngas via a gasification process.
Bioremediation:
an intervention strategy to enhance biodegradation of spilled oil (or other contaminants) ranging from no remedial action other than monitoring (natural attenuation) to nutrient addition (biostimulation) to inoculation with competent microbial communities (bioaugmentation)
Bitumen:
a semisolid to solid organic material found filling pores and crevices of sandstone, limestone, or argillaceous sediments; contains organic carbon, hydrogen, nitrogen, oxygen, sulfur, and metallic constituents; usually has an API gravity (<10°), but other properties are necessary for inclusion in a more complete definition; in its natural state, tar sand (oil sand) bitumen is not recoverable at a commercial rate through a well because it is too viscous to flow; bitumen typically makes up approximately 10% w/w of tar sand (oil sand), but saturation varies
Boiling Point:
a characteristic physical property of a liquid at which the vapor pressure is equal to that of the atmosphere and the liquid is converted to a gas
Boiling Range:
the range of temperature, usually determined at atmospheric pressure in a standard laboratory apparatus, over which the distillation of oil commences, proceeds, and finishes
Bottom-of-the-Barrel:
residuum (q.v.)Brønsted Acid: a chemical species that can act as a source of protons
Brønsted Base:
a chemical species that can accept protons
BTEX:
benzene, toluene, ethylbenzene, and the xylene isomers
BTU (British Thermal Unit):
the energy required to increase the temperature of 1 lb of water to 1°FBunker C Oil: see No. 6 fuel oil
Burner Fuel Oil:
any petroleum liquid suitable for combustion
Burning Oil:
illuminating oil, such as kerosene suitable for burning in a wick lamp
Burning Point:
see fire point
Carbon Dioxide-Augmented Waterflooding:
injection of carbonated water or water and carbon dioxide to increase water flood efficiency; see immiscible carbon dioxide displacement
Carbon Residue:
the amount of carbonaceous residue remaining after thermal decomposition of petroleum, a petroleum fraction, or a petroleum product in a limited amount of air; also called the coke- or carbon-forming propensity; often prefixed by the terms Conradson or Ramsbottom in reference to the inventor of the respective tests
Catalyst:
a chemical agent that, when added to a reaction (process), will enhance the conversion of a feedstock without being consumed in the process; used in upgrading processes to assist cracking and other upgrading reactions
Catalyst Plugging:
the deposition of carbon (coke) or metal contaminants that decreases the flow through the catalyst bed
Catalyst Poisoning:
the deposition of carbon (coke) or metal contaminants that causes the catalyst to become nonfunctional
Catalyst Selectivity:
the relative activity of a catalyst with respect to a particular compound in a mixture or the relative rate in competing reactions of a single reactant
Catalyst Stripping:
the introduction of steam at a point where spent catalyst leaves the reactor in order to strip, i.e. remove, deposits retained on the catalyst
Catalytic Activity:
the ratio of the space velocity of the catalyst under test to the space velocity required for the standard catalyst to give the same conversion as the catalyst being tested; usually multiplied by 100 before being reported
Catalytic Cracking:
the conversion of high-boiling feedstocks into lower-boiling products by means of a catalyst that may be used in a fixed bed (q.v.) or fluid bed (q.v.)
Catalytic Distillation:
a process that combines reaction and distillation in a single vessel resulting in lower investment and operating costs, as well as process benefits
Catalytic Hydrocracking:
a refining process that uses hydrogen and catalysts with relatively low temperatures and high pressures for converting middle-boiling or residual material to high-octane gasoline, reformer charge stock, jet fuel, and/or high-grade fuel oil. The process uses one or more catalysts, depending on product output, and can handle high-sulfur feedstocks without prior desulfurization.
Catalytic Hydrotreating:
a refining process for treating petroleum fractions from atmospheric or vacuum distillation units (e.g. naphtha, middle distillates, reformer feeds, residual fuel oil, and heavy gas oil) and other petroleum (e.g., cat cracked naphtha, coker naphtha, gas oil, etc.) in the presence of catalysts and substantial quantities of hydrogen. Hydrotreating includes desulfurization, removal of substances (e.g. nitrogen compounds) that deactivate catalysts, conversion of olefins to paraffins to reduce gum formation in gasoline, and other processes to upgrade the quality of the fractions.
Catalytic Reforming:
rearranging hydrocarbon molecules in a gasoline-boiling-range feedstock to produce other hydrocarbons having a higher antiknock quality; isomerization of paraffins, cyclization of paraffins to naphthenes (q.v.), dehydrocyclization of paraffins to aromatics (q.v.)
Caustic Wash:
the process of treating a product with a solution of caustic soda to remove minor impurities; often used in reference to the solution itself
Cetane Number:
a number indicating the ignition quality of diesel fuel; a high cetane number represents a short ignition delay time; the ignition quality of diesel fuel can also be estimated from the following formula:
Diesel index = [aniline point (°F) × API gravity]100
Chelating Agents:
complex-forming agents having the ability to solubilize heavy metals
Chemical Composition:
the makeup of petroleum in terms of distinct chemical types such as paraffins, isoparaffins, naphthenes (cycloparaffins), benzenes, diaromatics, triaromatics, polynuclear aromatics; other chemical types can also be specified
Chemical Octane Number:
the octane number added to gasoline by refinery processes or by the use of octane number (q.v.) improvers such as tetraethyl lead
Chemical Waste:
any solid, liquid, or gaseous material discharged from a process and that may pose substantial hazards to human health and the environment
Chevron Deasphalted Oil Hydrotreating Process:
a process designed to desulfurize heavy feedstocks that have had the asphaltene fraction (q.v.) removed by prior application of a deasphalting process (q.v.)
Chevron RDS and VRDS Processes:
processes designed to remove sulfur, nitrogen, asphaltene, and metal contaminants from heavy feedstocks consisting of a once-through operation of the feedstock coming into contact with hydrogen and the catalyst in a downflow reactor (q.v.)
Chromatographic Adsorption:
selective adsorption on materials such as activated carbon, alumina, or silica gel; liquid or gaseous mixtures of hydrocarbons are passed through the adsorbent in a stream of diluent and certain components are preferentially adsorbed
Chromatography:
a method of separation based on selective adsorption; see also chromatographic adsorption.
Clay:
silicate minerals that also usually contain aluminum and have particle sizes <0.002 micron; used in separation methods as an adsorbent and in refining as a catalyst
Cloud Point:
the temperature at which paraffin wax or other solid substances begin to crystallize or separate from the solution imparting a cloudy appearance to the oil when the oil is chilled under prescribed conditions
Coal:
an organic rock; a readily combustible black or brownish-black rock whose composition, including inherent moisture, consists of >50% w/w and >70% v/v of carbonaceous material; formed from plant remains that have been compacted, hardened, chemically altered, and metamorphosed by heat and pressure over geologic time
Coal Tar:
the specific name for the tar (q.v.) produced from coal
Coal Tar Pitch:
the specific name for the pitch (q.v.) produced from coal
Cogeneration:
the simultaneous production of electricity and steam
Coke:
a gray to black solid carbonaceous material produced from petroleum during thermal processing; characterized by having a high carbon content (95%+ by weight) and a honeycomb type of appearance and is insoluble in organic solvents
Coking:
a process for the thermal conversion of petroleum in which gaseous, liquid, and solid (coke) products are formed; e.g. delayed coking (q.v.) or fluid coking (q.v.)
Condensate:
a mixture of light hydrocarbon liquids obtained by condensation of hydrocarbon vapors, predominately butane, propane, and pentane with some heavier hydrocarbons and relatively little methane or ethane; see also natural gas liquids
Conradson Carbon Residue:
see carbon residue
Contaminant:
a substance that causes deviation from the normal composition of an environment
Conventional Crude Oil:
a mixture mainly of pentane and heavier hydrocarbons recoverable at a well from an underground reservoir and liquid at atmospheric pressure and temperature; unlike some heavy oils and tar sand bitumen, conventional crude oil flows through a well without stimulation and through a pipeline without processing or dilution; generally, conventional crude oil includes light- and medium-gravity crude oils; crude oil containing >0.5% w/w sulfur is considered to be sour crude oil, while crude oil with <0.5% w/w sulfur is to be sweet crude oil
Conventional Gasoline:
finished automotive gasoline not included in the oxygenated or reformulated gasoline categories; excludes reformulated gasoline blendstock for oxygenate blending (RBOB) as well as other blendstocks
Cracking:
the thermal processes by which the constituents of petroleum are converted to lower molecular weight products
Cracking Temperature:
the temperature (350°C, 660°F) at which the rate of thermal decomposition of petroleum constituents becomes significant
Crude assay:
a procedure for determining the general distillation characteristics (e.g. distillation profile, q.v.) and other quality information of crude oil
Crude Oil:
see petroleum
Cumene:
a colorless liquid [C6H5CH (CH3)2] used as an aviation gasoline blending component and as an intermediate in the manufacture of chemicals
Cyclization:
the process by which an open-chain hydrocarbon structure is converted to a ring structure, e.g. hexane to benzene
Cyclone:
a device for extracting dust from industrial waste gases. It is in the form of an inverted cone into which the contaminated gas enters tangentially from the top; the gas is propelled down a helical pathway and the dust particles are deposited by means of centrifugal force onto the wall of the scrubber.
Deactivation:
reduction in catalyst activity by the deposition of contaminants (e.g. coke, metals) during a process.
Dealkylation:
the removal of an alkyl group from aromatic compounds
Deasphaltened Oil:
the fraction of petroleum after the asphaltenes have been removed using liquid hydrocarbons, such as n-pentane and n-heptane
Deasphaltening:
removal of a solid powdery asphaltene fraction from petroleum by the addition of the low-boiling liquid hydrocarbons, such as n-pentane or n-heptane, under ambient conditions
Deasphalting:
the removal of asphalt (tacky, semisolid, higher molecular weight) constituents from petroleum (as occurs in a refinery asphalt plant) by the addition of liquid propane or liquid butane under pressure; also, the removal of the asphaltene fraction from petroleum by the addition of a low-boiling hydrocarbon liquid, such as n-pentane or n-heptane
Dehydrogenation:
the removal of hydrogen from a chemical compound; for example, the removal of two hydrogen atoms from butane to make butene(s) as well as the removal of additional hydrogen to produce butadiene
Density:
the mass (or weight) of a unit volume of any substance at a specified temperature; also, the heaviness of crude oil indicating the proportion of large, carbon-rich molecules, generally measured in kilograms per cubic meter (kg/m3) or degrees on the API gravity scale; in some countries, oil up to 900 kg/m3 is considered light to medium crude; see also specific gravity
Desalting:
removal of mineral salts (mostly chlorides) from crude oils
Desulfurization:
the removal of sulfur or sulfur compounds from a feedstock; a process that removes sulfur and its compounds from various streams during the refining process; desulfurization processes include catalytic hydrotreating and other chemical/physical processes, such as absorption; the desulfurization processes vary based on the type of stream treated (e.g. naphtha, distillate, heavy gas oil, etc.) and the amount of sulfur removed (e.g. sulfur reduction to 10 ppm)
Dewaxing:
see solvent dewaxing
Diesel Fuel:
fuel used for internal combustion in diesel engines; usually the fraction that distills after kerosene
Diesel Hydrotreater:
a refinery process unit for production of clean (low-sulfur) diesel fuel
Diesel Index:
an approximation of the cetane number (q.v.) of diesel fuel (q.v.) calculated from the density (q.v.) and aniline point (q.v.)
Diesel Knock:
the result of a delayed period of ignition and the accumulation of diesel fuel in the engine
Diluted Crude:
heavy crude oil to which a diluent (thinner) has been added to reduce viscosity and facilitate pipeline flow
Dispersant:
a chemical or mixture of chemicals applied, for example to an oil spill to disperse the oil phase into small droplets in the water phase
Dispersion:
suspension of oil droplets in water accomplished by natural wind and wave action, production of biological materials (biosurfactants) and/or chemical dispersant formulations
Distillate:
the products of distillation formed by condensing vapors
Distillate Fuel Oil:
a general classification for one of the petroleum fractions produced in conventional distillation operations. It includes diesel fuels and fuel oils. Products known as No. 1, No. 2, and No. 4 diesel fuel are used in on-highway diesel engines, such as those in trucks and automobiles, as well as off-highway engines, such as those in railroad locomotives and agricultural machinery. Products known as No. 1, No. 2, and No. 4 fuel oils are used primarily for space heating and electric power generation.
Distillation:
a process for separating liquids with different boiling points without thermal decomposition of the constituents (see destructive distillation)
Distillation Curve:
see distillation profile
Distillation Loss:
the difference, in a laboratory distillation, between the volume of liquid originally introduced into the distilling flask and the sum of the residue and the condensate recovered
Distillation Profile:
the distillation characteristics of petroleum or a petroleum product showing the temperature and the percent distilled
Distillation Range:
the difference between the temperature at the initial boiling point and at the end point, as obtained by the distillation test
Domestic Heating Oil:
see No. 2 fuel oil
Downcomer:
a means of conveying liquid from one tray to the next below in a bubble tray column (q.v.)
Downstream:
a sector of the petroleum industry that refers to the refining of crude oil and the products derived from crude oil
Dry Gas:
a gas that does not contain fractions that may easily condense under normal atmospheric conditions
Drying:
removal of a solvent or water from a chemical substance; also referred to as the removal of solvent from a liquid or suspension
Dry Point:
the temperature at which the last drop of petroleum fluid evaporates in a distillation test
Effective Viscosity:
see apparent viscosity
Effluent:
any contaminating substance, usually a liquid, that enters the environment via a domestic industrial, agricultural, or sewage plant outlet
Electric Desalting:
a continuous process to remove inorganic salts and other impurities from crude oil by settling out in an electrostatic field
Electrical Precipitation:
a process using an electrical field to improve the separation of hydrocarbon reagent dispersions; may be used in chemical treating processes on a wide variety of refinery stocks
Electrofining:
a process for contacting a light hydrocarbon stream with a treating agent (acid, caustic, doctor, etc.), then assisting the action of separation of the chemical phase from the hydrocarbon phase by an electrostatic field
Electrolytic Mercaptan Process:
a process in which aqueous caustic solution is used to extract mercaptans from refinery streams
Electrostatic Precipitators:
devices used to trap fine dust particles (usually in the size range 30–60 microns) that operate on the principle of imparting an electric charge to particles in an incoming air stream and which are then collected on an oppositely charged plate across a high-voltage field
Emission Control:
the use of gas cleaning processes to reduce emissions
Emission Standard:
the maximum amount of a specific pollutant permitted to be discharged from a particular source in a given environment
Emulsification:
formation of water droplets in an oil matrix (water-in-oil) or, conversely, oil droplets in a water matrix (oil-in-water) achieved by the action of agitation, such as wind and wave activity; can be unstable, separating into oil and water phases again soon after formation or stable for months or years (e.g. ‘chocolate mousse’, a water-in-oil emulsion).
Emulsion Breaking:
the settling or aggregation of colloidal-sized emulsions from suspension in a liquid medium
End-of-Pipe Emission Control:
the use of specific emission control processes to clean gases after production of the gases
Energy:
the capacity of a body or system to do work, measured in joules (SI units); also, the output of fuel sources
Energy from Biomass:
the production of energy from biomass (q.v.)
Enhanced Oil Recovery:
petroleum recovery following recovery by conventional (i.e. primary and/or secondary) methods; the third stage of production during which sophisticated techniques that alter the original properties of the oil are used. Enhanced oil recovery can begin after a secondary recovery process or at any time during the productive life of an oil reservoir; the purpose is not only to restore formation pressure, but also to improve oil displacement or fluid flow in the reservoir. The three major types of enhanced oil recovery operations are chemical flooding (alkaline flooding or micellar-polymer flooding), miscible displacement (carbon dioxide injection or hydrocarbon injection), and thermal recovery (steam flood). The optimal application of each method depends on reservoir temperature, pressure, depth, net pay, permeability, residual oil and water saturations, porosity, and fluid properties, such as oil API gravity and viscosity.
ETBE [Ethyl Tertiary Butyl Ether, (CH3)3COC2H]:
an oxygenated blend stock formed by the catalytic etherification of isobutylene with ethanol
Ethane (C2H6):
a straight-chain saturated (paraffinic) hydrocarbon extracted predominantly from the natural gas stream, which is gaseous at standard temperature and pressure; a colorless gas that boils at a temperature of −88°C (−127°F)
Ethanol:
see ethyl alcohol
Ether:
a generic term applied to a group of organic chemical compounds composed of carbon, hydrogen, and oxygen characterized by an oxygen atom attached to two carbon atoms (e.g. methyl tertiary butyl ether)
Ethyl Alcohol (ethanol or grain alcohol):
an inflammable organic compound (C2H5OH) formed during fermentation of sugars; used as an intoxicant and as a fuel
Evaporation:
the physical loss of low molecular weight components of an oil to the atmosphere by volatilization
Ethylene (C2H4):
an olefin hydrocarbon recovered from refinery or petrochemical processes that is gaseous at standard temperature and pressure. Ethylene is used as a petrochemical feedstock for many chemical applications and the production of consumer goods.
Extractive Distillation:
the separation of different components of mixtures that have similar vapor pressures by flowing a relatively high-boiling solvent, which is selective for one of the components in the feed, down a distillation column as the distillation proceeds; the selective solvent scrubs the soluble component from the vapor
FCC:
fluid catalytic cracking
FCCU:
fluidized catalytic cracking unit
Feedstock:
petroleum as it is fed to the refinery; a refinery product that is used as the raw material for another process; the term is also generally applied to raw materials used in other refinery processes or industrial processes
Filtration:
the use of an impassable barrier to collect solids, but which allows liquids to pass
Fischer-Tropsch Process:
a process for synthesizing hydrocarbons and oxygenated chemicals from a mixture of hydrogen and carbon monoxide
Fixed Bed:
a stationary bed (of catalyst) to accomplish a process (see fluid bed)
Flame Ionization Detector (FID):
used with analytical instruments like gas chromatographs to detect components of petroleum by combustion ionization, hence GC-FID
Flash Point:
the lowest temperature to which the product must be heated under specified conditions to give off sufficient vapor to form a mixture with air that can be ignited momentarily by a flame
Flue Gas:
gas from the combustion of fuel, the heating value of which has been substantially spent and which is, therefore, discarded to the flue or stack; gas that is emitted to the atmosphere via a flue, which is a pipe for transporting exhaust fumes
Fluid Bed:
a bed (of catalyst) that is agitated by an upward passing gas in such a manner that the particles of the bed simulates the movement of a fluid and has the characteristics associated with a true liquid; cf. fixed bed
Fluid Catalytic Cracking:
cracking in the presence of a fluidized bed of catalyst
Fluid Coking:
a continuous fluidized solids process that cracks feed thermally over heated coke particles in a reactor vessel to gas, liquid products, and coke
Fluidized Catalytic Cracking:
a refinery process used to convert the heavy portion of crude oil into lighter products, including liquefied petroleum gas and gasoline
Fly Ash:
particulate matter produced from mineral matter in coal that is converted during combustion to finely divided inorganic material and which emerges from the combustor in the gases
Fossil Fuel Resources:
a gaseous, liquid, or solid fuel material formed in the ground by chemical and physical changes (diagenesis, q.v.) in plant and animal residues over geological time; natural gas, petroleum, coal, and oil shale
Fraction:
a group of hydrocarbons that have similar boiling points; a portion of crude oil defined by boiling range; naphtha, kerosene, gas oil, and residuum are fractions of crude oil
Fractional Composition:
the composition of petroleum as determined by fractionation (separation) methods
Fractional Distillation:
the separation of the components of a liquid mixture by vaporizing and collecting the fractions or cuts, which condense in different temperature ranges; a common form of separation technology in hydrocarbon-processing plants wherein a mixture (e.g. crude oil) is heated in a large, vertical cylindrical column to separate compounds (fractions) according to their boiling points
Fractionating Column:
a column arranged to separate various fractions of petroleum by a single distillation which may be tapped at different points along its length to separate various fractions in the order of their boiling points
Fractionation:
the separation of petroleum into the constituent fractions using solvent or adsorbent methods; chemical agents such as sulfuric acid may also be used
Free Sulfur:
sulfur that exists in the elemental state associated with petroleum; sulfur that is not bound organically within the petroleum constituents
Fuel Oil:
also called heating oil, is a distillate product that covers a wide range of properties; see also No. 1 to No. 4 fuel oils
Functional Group:
the portion of a molecule that is characteristic of a family of compounds and determines the properties of these compounds
Furfural Extraction:
a single-solvent process in which furfural is used to remove aromatic components, naphthene components, olefins, and unstable hydrocarbons from a lubricating oil charge stock
Furnace Oil:
a distillate fuel primarily intended for use in domestic heating equipment.
Gaseous Pollutants:
gases released into the atmosphere that act as primary or secondary pollutants
Gasification:
a process to partially oxidize any hydrocarbon, typically heavy residues, to a mixture of hydrogen and carbon monoxide; the process can be used to produce hydrogen and various energy by-products
Gasohol:
a term for motor vehicle fuel comprising between 80% and 90% unleaded gasoline and 10–20% ethanol (see also ethyl alcohol)
Gas Chromatography (GC):
an analytical method used to characterize petroleum components; GC is combined with different detection methods, hence GC-FID, GC-MS, etc.
Gas Oil:
a petroleum distillate with a viscosity and boiling range between those of kerosene and lubricating oil; a middle-distillate petroleum fraction; usually includes diesel, kerosene, heating oil, and light fuel oil; a liquid petroleum distillate having a viscosity intermediate 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; heavy gas oil is petroleum distillates with an approximate boiling range from 345°C to 540°C (650–1000°F)
Gas-Oil Ratio:
ratio of the number of cubic feet of gas measured at atmospheric (standard) conditions to barrels of produced oil measured at stock tank conditions
Gasoline:
fuel for the internal combustion engine that is commonly, but improperly, referred to simply as gas
Gasoline Blending Components:
naphtha fractions that will be used for blending or compounding into finished aviation or automotive gasoline (e.g. straight-run gasoline, alkylate, reformate, benzene, toluene, and xylene); excludes oxygenates (alcohols, ethers), butane, and pentanes plus
Gas-to-Liquids (GTL):
a process used to convert natural gas into longer-chain hydrocarbons such as diesel and jet fuel. Methane-rich gases are converted into liquid syngas (a mix of carbon monoxide and hydrogen) produced using steam methane reforming or autothermal reforming, followed by the Fischer–Tropsch process. Hydrocracking is then used to produce finished fuels.
Greenhouse Effect:
warming of the earth due to entrapment of the energy of the sun by the atmosphere
Greenhouse Gases:
gases that contribute to the greenhouse effect (q.v.)
Gum:
an insoluble tacky semisolid material formed as a result of the storage instability and/or the thermal instability of petroleum and petroleum products
Heat Exchanger:
a device used to transfer heat from a fluid on one side of a barrier to a fluid on the other side without bringing the fluids into direct contact
Heating Oil:
see fuel oil
Heavy Feedstock:
any feedstock of the type heavy oil (q.v.), bitumen (q.v.), atmospheric residuum (q.v.), vacuum residuum (q.v.), and solvent deasphalter bottoms (q.v.)
Heavy Fuel Oil:
fuel oil having a high density and viscosity; generally residual fuel oil such as No. 5 and No 6. fuel oil (q.v.)
Heavy Gas Oil:
a petroleum distillate with an approximate boiling range from 345°C to 540°C (650–1000°F)
Heavy Oil:
petroleum having an API gravity of <20°; other properties are necessary for inclusion in a more complete definition
Heavy Petroleum:
see heavy oil.
Heavy Residue Gasification and Combined Cycle Power Generation:
a process for producing hydrogen from residuals
Heteroatom:
in petroleum, an atom such as nitrogen, sulfur, and/or oxygen that is part of a hydrocarbon skeleton, such as found in the resins fraction of crude oils
Heteroatom Compounds:
chemical compounds that contain nitrogen and/or oxygen and/or sulfur and/or metals bound within their molecular structure(s)
High-Boiling Distillates:
fractions of petroleum that cannot be distilled at atmospheric pressure without decomposition, e.g. gas oils
High Molecular Weight (HMW):
relative term referring to the molecular mass of chemicals; in oil, asphaltenes would be typical of HMW compounds
High performance liquid chromatography (HPLC):
an analytical method for separating chemicals in solution
High-Sulfur Diesel (HSD):
diesel fuel containing >500 ppm sulfur
High-Sulfur Petroleum:
a general expression for petroleum having >1% wt. sulfur; this is a very approximate definition and should not be construed as having a high degree of accuracy because it does not take into consideration the molecular locale of the sulfur. All else being equal, there is little difference between petroleum having 0.99% wt. sulfur and petroleum having 1.01% wt. sulfur.
Hydrocarbon:
a chemical that is composed of only carbon and hydrogen; chemicals containing heteroatoms, such as nitrogen, sulfur and/or oxygen, are not hydrocarbons, even though they may contain petroleum constituents
Hydrocarbon Gasification Process:
a continuous, noncatalytic process in which hydrocarbons are gasified to produce hydrogen by air or oxygen
Hydrocarbon Gas Liquids (HGL):
a group of hydrocarbons including ethane, propane, n-butane, isobutane, natural gasoline, and their associated olefins, including ethylene, propylene, butylene, and isobutylene; excludes liquefied natural gas
Hydrocarbon Resource:
resources such as petroleum and natural gas that can produce naturally occurring hydrocarbons without the application of conversion processes
Hydrocarbon-Producing Resource:
a resource such as coal and oil shale (kerogen) that produces derived hydrocarbons by the application of conversion processes; the hydrocarbons produced are not naturally occurring materials
Hydroconversion:
a term often applied to hydrocracking (q.v.)
Hydrocracker:
a refinery process unit in which hydrocracking occurs
Hydrocracking:
a catalytic high-pressure, high-temperature process for the conversion of petroleum feedstocks in the presence of fresh and recycled hydrogen; carbon–carbon bonds are cleaved in addition to the removal of heteroatomic species
Hydrocracking Catalyst:
a catalyst used for hydrocracking that typically contains separate hydrogenation and cracking functions
Hydrodenitrogenation:
the removal of nitrogen by hydrotreating (q.v.)
Hydrodesulfurization:
the removal of sulfur by hydrotreating (q.v.)
Hydrodemetallization:
the removal of metallic constituents by hydrotreating (q.v.)
Hydrodesulfurization:
a refining process that removes sulfur from liquid and gaseous hydrocarbons
Hydrofining:
a fixed-bed catalytic process to desulfurize and hydrogenate a wide range of charge stocks from gases through waxes
Hydroforming:
a process in which naphtha is passed over a catalyst at elevated temperatures and moderate pressures, in the presence of added hydrogen or hydrogen-containing gases to form high-octane motor fuel or aromatics
Hydrogen:
the lightest of all gases occurring chiefly in combination with oxygen in water; exists also in acids, bases, alcohols, petroleum, and other hydrocarbons
Hydrogenation:
the chemical addition of hydrogen to a material. In nondestructive hydrogenation, hydrogen is added to a molecule only if, and where, unsaturation with respect to hydrogen exists; classed as destructive (hydrocracking) or nondestructive (hydrotreating)
Hydroprocessing:
a term often equally applied to hydrotreating (q.v.) and to hydrocracking (q.v.); also, often collectively applied to both
Hydrotreater:
a refinery process unit that removes sulfur and other contaminants from hydrocarbon streams
Hydrotreating:
the removal of heteroatomic (nitrogen, oxygen, and sulfur) species by treatment of a feedstock or product at relatively low temperatures in the presence of hydrogen
Hydrovisbreaking:
a noncatalytic process conducted under similar conditions to visbreaking, which involves treatment with hydrogen to reduce the viscosity of the feedstock and produce more stable products than is possible with visbreaking
Hydrogen Sulfide (H2S):
a toxic, flammable, and corrosive gas sometimes associated with petroleum
Inhibitor:
a substance, the presence of which, in small amounts, in a petroleum product prevents or retards undesirable chemical changes from taking place in the product or in the condition of the equipment in which the product is used
Iodine Number:
a measure of the iodine absorption by an oil under standard conditions; used to indicate the quantity of unsaturated compounds present; also called iodine value
Ion Exchange:
a means of removing cations or anions from solution onto a solid resin
Isomerate Process:
a fixed-bed isomerization process to convert pentane, hexane, and heptane to high-octane blending stocks
Isomerization:
the conversion of a normal (straight-chain) paraffin hydrocarbon into an iso- (branched-chain) paraffin hydrocarbon having the same atomic composition; a refining process that alters the fundamental arrangement of atoms in the molecule without adding or removing anything from the original material; used to convert normal butane into isobutane (C4), an alkylation process feedstock, and normal pentane and hexane into isopentane (C5) and isohexane (C6), high-octane gasoline components
Isomers:
chemicals that have the same molecular formula (i.e. elemental composition), but different structures; may also have different properties, including water solubility, biodegradability, and toxicity
Jet Fuel:
fuel meeting the required properties for use in jet engines and aircraft turbine engines
Kaolinite:
a clay mineral formed by hydrothermal activity at the time of rock formation or by chemical weathering of rocks with high feldspar content; usually associated with intrusive granite rocks with high feldspar content
Kerogen:
a complex carbonaceous (organic) material that occurs in sedimentary rocks and shale formations; generally insoluble in common organic solvents
Kerosene (kerosine):
a fraction of petroleum that was initially sought as an illuminant in lamps; a precursor to diesel fuel; 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°F at the 10% recovery point, a final boiling point of 572°F, and a minimum flash point of 100°F. 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°F at the 10% recovery point and a final maximum boiling point of 572°F 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.
Kinematic Viscosity:
the ratio of viscosity (q.v.) to density, both measured at the same temperature
Knock:
the noise associated with self-ignition of a portion of the fuel–air mixture ahead of the advancing flames front
Kow:
the partition coefficient describing the equilibrium concentration ratio of a dissolved chemical in octanol versus in water, in a two-phase system at a specific temperature; used in prediction of toxicity
Lewis Acid:
a chemical species that can accept an electron pair from a base
Lewis Base:
a chemical species that can donate an electron pair
Light Crude Oil:
crude oil with a high proportion of light hydrocarbon fractions and low metallic compounds; sometimes defined as crude oil, with a gravity of 28° API or higher; a high-quality light crude oil might have a gravity of approaching 40° API, such as light Arabian crude oil (32–34° API) and West Texas Intermediate crude oil (37–40° API)
Light Ends:
the lower-boiling components of a mixture of hydrocarbons; see also heavy ends, light hydrocarbons
Light Gas Oil:
liquid petroleum distillates that are higher boiling than naphtha
Light Hydrocarbons:
hydrocarbons with molecular weights less than that of heptane (C7H16)
Light Oil:
the products distilled or processed from crude oil up to, but not including, the first lubricating oil distillate
Light Petroleum:
petroleum having an API gravity >20°
Liquefied Natural Gas (LNG):
natural gas cooled to a liquid state
Liquefied Petroleum Gas:
propane, butane, or mixtures thereof, gaseous at atmospheric temperature and pressure, held in the liquid state by pressure to facilitate storage, transport, and handling
Liquefied Refinery Gases (LRG):
hydrocarbon gas liquids produced in refineries from processing of crude oil and unfinished oils. They are retained in the liquid state through pressurization and/or refrigeration; includes ethane, propane, n-butane, isobutane, and refinery olefins (ethylene, propylene, butylene, and isobutylene).
Liquid Fuels:
products of petroleum refining, natural gas liquids, biofuels, and liquids derived from other sources (including coal-to-liquids and gas-to-liquids); liquefied natural gas and liquid hydrogen are not included
Low-Boiling Distillates:
fractions of petroleum that can be distilled at atmospheric pressure without decomposition
Low Molecular Weight:
relative terms referring to the molecular mass of chemicals; in oil,mono-aromatics and aliphatics up to C10 would be typical of these compounds
Low-Sulfur Petroleum:
a general expression for petroleum having <1% wt. sulfur; this is a very approximate definition and should not be construed as having a high degree of accuracy because it does not take into consideration the molecular locale of the sulfur. All else being equal, there is little difference between petroleum having 0.99% wt. sulfur and petroleum having 1.01% wt. sulfur
Lube:
see lubricating oil
Lubricants:
substances used to reduce friction between bearing surfaces or 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; includes all grades of lubricating oils, from spindle oil to cylinder oil to those used in grease.
Lubricating Oil:
a fluid lubricant used to reduce friction between bearing surfaces
Maltenes:
the fraction of petroleum that is soluble in, for example, pentane or heptane; deasphaltened oil (q.v.); also, the term arbitrarily assigned to the pentane-soluble portion of petroleum that is relatively high boiling (>300°C, 760 mm) (see also petrolenes)
Mass Spectrometry:
an analytical method used for detailed characterization of petroleum components, often in combination with GC, hence GC-MS
Marine Engine Oil:
oil used as a crankcase oil in marine engines
Marine Gasoline:
fuel for motors in marine service
Medium Crude Oil:
crude oil with gravity between (approximately) 20° and 28° API
Medium Molecular Weight:
relative terms referring to the molecular mass of chemicals; in oil, 3 to 6-ringed PAH and aliphatics up to C20 would be typical of MMW compounds
Methanol:
see methyl alcohol
MEOR:
microbial enhanced oil recovery
Mercaptans:
odiferous organic sulfur compounds with the general formula R-SH
Metagenesis:
the alteration of organic matter during the formation of petroleum that may involve temperatures above 200°C (390°F); see also catagenesis and diagenesis
Methanol (methyl alcohol, CH3OH):
a low-boiling alcohol eligible for gasoline blending
Methyl Alcohol (methanol; wood alcohol):
a colorless, volatile, inflammable, and poisonous alcohol (CH3OH) traditionally formed by destructive distillation (q.v.) of wood or, more recently, as a result of synthetic distillation in chemical plants
Methyl T-Butyl Ether:
an ether added to gasoline to improve its octane rating and to decrease gaseous emissions; see oxygenate
Microemulsion (micellar/emulsion) Flooding:
an augmented water flooding technique in which a surfactant system is injected in order to enhance oil displacement toward producing wells
Mid-Boiling Point:
the temperature at which approximately 50% of a material has distilled under specific conditions
Middle Distillate:
distillate boiling between the kerosene and lubricating oil fractions; a general classification of refined petroleum products that includes distillate fuel oil and kerosene
Mineralization:
complete oxidation of a compound (e.g., hydrocarbon) to carbon dioxide and water; may be accomplished by a single species of organism or by a community of microbes
Mitigation:
identification, evaluation, and cessation of potential impacts of a process product or by-product
Mode of Action (MoA):
describes a functional or anatomical change at the cellular level, resulting from the exposure of a living organism to a substance
Molecular Weight:
the mass of one molecule
Mono-Aromatics:
aromatic hydrocarbons having only a single benzene ring; may also have one or more alkyl side chains
MTBE [Methyl Tertiary Butyl Ether, (CH3)3COCH3]:
an ether intended for gasoline blending; see methyl t-butyl ether, oxygenates
Naphtha:
a generic term applied to refined, partly refined, or unrefined petroleum products and liquid products of natural gas, the majority of which distills below 240°C (464°F); the volatile fraction of petroleum that is used as a solvent or as a precursor to gasoline
Naphtha-Type Jet Fuel:
a fuel in the heavy naphtha boiling range having an average gravity of 52.8° API, 20% to 90% distillation temperatures of 290–470°F, and meeting Military Specification MIL-T-5624L (Grade JP-4); primarily used for military turbojet and turboprop aircraft engines because it has a lower freeze point than other aviation fuels and meets engine requirements at high altitudes and speeds
Naphthenes:
cycloparaffins; one of three basic hydrocarbon classifications found naturally in crude oil; used widely as petrochemical feedstock
Natural Gas:
the naturally occurring gaseous constituents that are found in many petroleum reservoirs; also, there are reservoirs in which natural gas may be the sole occupant
Natural Gas Liquids (NGL):
the hydrocarbon liquids that condense during the processing of hydrocarbon gases that are produced from an oil or gas reservoir; see also natural gasoline
Natural Gasoline:
a mixture of liquid hydrocarbons extracted from natural gas (q.v.) suitable for blending with refinery gasoline
Neutralization:
a process for reducing the acidity or alkalinity of a waste stream by mixing acids and bases to produce a neutral solution; also known as pH adjustment
No. 1 Fuel Oil:
very similar to kerosene (q.v.) and is used in burners where vaporization before burning is usually required and a clean flame is specified
No. 2 Diesel Fuel:
a distillate fuel oil that has a distillation temperature of 640°F at the 90% recovery point and meets the specifications defined in ASTM Specification D 975. It is used in highspeed diesel engines that are generally operated under uniform speed and load conditions, such as those in railroad locomotives, trucks, and automobiles.
No. 2 Fuel Oil:
also called domestic heating oil; has properties similar to diesel fuel and heavy jet fuel; used in burners where complete vaporization is not required before burning
No. 4 Fuel Oil:
a light industrial heating oil; is used where preheating is not required for handling or burning; there are two grades of No. 4 fuel oil, differing in safety (flash point) and flow (viscosity) properties
No. 5 Fuel Oil:
a heavy industrial fuel oil that requires preheating before burning
No. 6 Fuel Oil:
a heavy fuel oil; more commonly known as Bunker C oil when it is used to fuel ocean-going vessels; preheating is always required for burning this oil
Octane Number:
a number indicating the antiknock characteristics of gasoline
Octane Rating:
a number used to indicate gasoline’s antiknock performance in motor vehicle engines. The two recognized laboratory engine test methods for determining the antiknock rating, i.e. octane rating, of gasolines are the research method and the motor method. To provide a single number as guidance to the consumer, the antiknock index (R + M)/2 is the average of the research and motor octane numbers; see octane number
Oil Shale:
a fine-grained impervious sedimentary rock that contains an organic material called kerogen; the term oil shale describes the rock in lithological terms, but also refers to the ability of the rock to yield oil upon heating which causes the kerogen to decompose; also called black shale, bituminous shale, carbonaceous shale, coaly shale, kerosene shale, coorongite, maharahu, kukersite, kerogen shale, and algal shale.
Olefins:
a class of unsaturated double-bond linear hydrocarbons recovered from petroleum; examples include ethylene, propylene, and butene. Olefins are used to produce a variety of products, including plastics, fibers, and rubber.
Organic Sedimentary Rocks:
rocks containing organic material such as residues of plant and animal remains/decay
Paraffins:
a group of generally saturated single-bond linear hydrocarbons; also celled alkanes
Partitioning:
the diffusion of compounds between two immiscible liquid phases, including water and oil droplets and water and lipid membranes
Petrol:
a term commonly used in some countries for gasoline
Petroleum (crude oil):
a naturally occurring mixture of gaseous, liquid, and solid hydrocarbon compounds usually found trapped deep underground beneath impermeable cap rock and above a lower dome of sedimentary rock such as shale; most petroleum reservoirs occur in sedimentary rocks of marine, deltaic, or estuarine origin
Petroleum Coke:
a solid carbon fuel derived from oil refinery cracking processes such as delayed coking; also called pet coke
Petroleum Products:
products obtained from the processing of crude oil (including lease condensate), natural gas, and other hydrocarbon compounds. Petroleum products include unfinished oils, 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 feedstocks, special naphtha, lubricants, waxes, petroleum coke, asphalt, road oil, still gas, and miscellaneous products.
Petroleum Refining:
a complex sequence of events that result in the production of a variety of products
Phase Separation:
the formation of a separate phase that is usually the prelude to coke formation during a thermal process; the formation of a separate phase as a result of the instability/incompatibility of petroleum and petroleum products
pH Adjustment:
neutralization
Photo-Enhanced Toxicity:
increased toxicity due to photo-oxidation in vivo
Photo-Oxidation:
oxidation due to the influence of photic energy, usually from UV light
Pollution:
the introduction into the land, water, and air systems of a chemical or chemicals that are not indigenous to these systems or the introduction into the land, water, and air systems of indigenous chemicals in greater-than-natural amounts
Polycyclic Aromatic Hydrocarbons:
(PAHs) a subclass of aromatic hydrocarbons having two or more fused benzene rings; may also have one or more alkyl side chains, generating large suites of isomers; some are considered ‘priority pollutants’ because of their toxicity and/or potential carcinogenicity
Pore Diameter:
the average pore size of a solid material, e.g. catalyst
Pore Space:
a small hole in reservoir rock that contains fluid or fluids; a 4-in cube of reservoir rock may contain millions of interconnected pore spaces
Pore Volume:
total volume of all pores and fractures in a reservoir or part of a reservoir; also applied to catalyst samples
Porosity:
the percentage of rock volume available to contain water or other fluid
Porphyrins:
organometallic constituents of petroleum that contain vanadium or nickel; the degradation products of chlorophyll derivatives that became included in the protopetroleum
Pour Point:
the lowest temperature at which oil will pour or flow when it is chilled without disturbance under definite conditions
Propane (C3H8):
a straight-chain saturated (paraffinic) hydrocarbon extracted from natural gas or refinery gas streams, which is gaseous at standard temperature and pressure; a colorless gas that boils at a temperature of −42°C (−44°F) and includes all products designated in ASTM D1835 and Gas Processors Association specifications for commercial (HD-5) propane
Propylene (C3H6):
an olefin hydrocarbon recovered from refinery or petrochemical processes which is gaseous at standard temperature and pressure; an important petrochemical feedstock
Protopetroleum:
a generic term used to indicate the initial product formed as a result of chemical and physical changes that have occurred to the precursors of petroleum; a paleobotanical soup
Pyrolysis:
exposure of a feedstock to high temperatures in an oxygen-poor environment
Ramsbottom Carbon Residue:
see carbon residue
Reactor:
a vessel in which a reaction occurs during processing; usually defined by the nature of the catalyst bed, e.g. fixed-bed reactor, fluid-bed reactor, and by the direction of the flow of feedstock, e.g. upflow, downflow
Recycling:
the use or reuse of chemical waste as an effective substitute for commercial products or as an ingredient or feedstock in an industrial process
Refinery:
a series of integrated unit processes by which petroleum can be converted to a slate of useful (salable) products
Refining:
the process(es) by which petroleum is distilled and/or converted by application of a physical and chemical process to form a variety of products
Reforming:
the conversion of hydrocarbons with low octane numbers (q.v.) into hydrocarbons having higher octane numbers, for example, the conversion of a n-paraffin into an iso-paraffin
Regeneration:
the reactivation of a catalyst by burning off the coke deposits
Regenerator:
a reactor for catalyst reactivation
Renewable Energy Sources:
solar, wind, and other non-fossil fuel energy sources
Reserves:
well-identified resources that can be profitably extracted and utilized with existing technology
Reservoir:
a domain where a pollutant may reside for an indeterminate time resid: the heaviest boiling fraction remaining after initial processing (distillation) of crude oil; see residuum.
Residual Fuel Oil:
obtained by blending the residual product(s) from various refining processes with suitable diluent(s) (usually middle distillates) to obtain the required fuel oil grades; a general classification for the heavier oils, known as No. 5 and No. 6 fuel oils, that remain after the distillate fuel oils and lighter hydrocarbons are distilled away in refinery operations. It conforms to ASTM Specifications D396 and D975 and Federal Specification VV-F-815C. No. 5, a residual fuel oil of medium viscosity, is also known as Navy Special and is defined in Military Specification MIL-F-859E, including Amendment 2 (NATO Symbol F-770). It is used in steam-powered vessels in government service and inshore power plants. No. 6 fuel oil includes Bunker C fuel oil and is used for the production of electric power, space heating, vessel bunkering, and various industrial purposes.
Residual Oil:
see residuum
Residuals:
heavy fuel oils produced from the nonvolatile residue from the fractional distillation process; also called resids
Residuum (resid; pl. residua):
the residue obtained from petroleum after nondestructive distillation (q.v.) has removed all the volatile materials from crude oil, e.g. an atmospheric (345°C, 650°F+) residuum
Resins:
the portion of the maltenes (q.v.) that is adsorbed by a surface-active material such as clay or alumina; the fraction of deasphaltened oil that is insoluble in liquid propane but, soluble in n-heptane
Resource:
the total amount of a commodity (usually a mineral, but can include nonminerals such as water and petroleum) that has been estimated to be ultimately available
Riser:
the part of the bubble-plate assembly that channels the vapor and causes it to flow downward to escape through the liquid; also, the vertical pipe where fluid catalytic cracking reactions occur
Rock Asphalt:
bitumen that occurs in formations that have a limiting ratio of bitumen-to-rock matrix
SARA Separation:
a method of fractionation by which petroleum is separated into saturates, aromatics, resins, and asphaltene fractions
Saturates:
paraffins and cycloparaffins (naphthenes). They are a class of hydrocarbons that may be straight-chain, branched-chain, or cyclic, in which all carbon atoms have single bonds to either carbon or hydrogen.
Sediment:
an insoluble solid formed as a result of the storage instability and/or the thermal instability of petroleum and petroleum products
Separation Process:
an upgrading process in which the constituents of petroleum are separated, usually without thermal decomposition, e.g. distillation and deasphalting
Shale Oil:
also known as ‘tight oil’ (not to be confused with ‘oil shale’); liquid petroleum that is produced from shale oil reservoirs, typically by hydraulic fracturing methodsSludge: a semisolid to solid product that results from the storage instability and/or the thermal instability of petroleum and petroleum products.
Slurry Hydroconversion Process:
a process in which the feedstock is contacted with hydrogen under pressure in the presence of a catalytic coke-inhibiting additive
Solvent Extraction:
a process for separating liquids by mixing the stream with a solvent that is immiscible with part of the waste, but that will extract certain components of the waste stream
Sour Crude Oil:
crude oil containing an abnormally large amount of sulfur compounds (a >1% total sulfur content); see also sweet crude oil; crude oil containing free sulfur, hydrogen sulfide, or other sulfur compounds
Specific Gravity:
the mass (or weight) of a unit volume of any substance at a specified temperature compared with the mass of an equal volume of pure water at a standard temperature; see also density
Spent Catalyst:
catalyst that has lost much of its activity due to the deposition of coke and metals
Steam Cracking:
a conversion process in which the feedstock is treated with superheated steam; a petrochemical process sometimes used in refineries to produce olefins (e.g. ethylene) from various feedstock for petrochemicals manufacture; the feedstock ranges from ethane to vacuum gas oil, with heavier feeds giving higher yields of by-products, such as naphtha. The most common feedstocks are ethane, butane, and naphtha and the process is carried out at temperatures of 815–870°C (1500–1600°F) and at pressures slightly above atmospheric pressure. Naphtha produced from steam cracking contains benzene which is extracted before hydrotreating and high-boiling products (residua) from steam cracking are sometimes used as blend stock for heavy fuel oil.
Steam Distillation:
distillation in which vaporization of the volatile constituents is affected at a lower temperature by introduction of steam (open steam) directly into the charge
Storage Stability (storage instability):
the ability (inability) of a liquid to remain in storage over extended periods of time without appreciable deterioration as measured by gum formation and the depositions of insoluble material (sediment)
Sulfonic Acids:
acids obtained by the reaction of petroleum or a petroleum product with strong sulfuric acid
Sulfur:
a yellowish nonmetallic element sometimes known by the Biblical name of brimstone; present at various levels of concentration in many fossil fuels whose combustion releases sulfur compounds that are considered harmful to the environment. Some of the most commonly used fossil fuels are categorized according to their sulfur content, with lower sulfur fuels usually selling at a higher price.
Sulfur Recovery Unit (SRU):
a refinery process unit used to convert hydrogen sulfide to elemental sulfur using the Claus process
Sweet Crude:
petroleum with low total sulfur content, variously defined as <0.5% or <1% sulfur
Sweetening:
the process by which petroleum products are improved in odor and color by oxidizing or removing the sulfur-containing and unsaturated compounds
Synthetic Crude Oil (syncrude):
a hydrocarbon product produced by the conversion of coal, oil shale, or tar sand bitumen that resembles conventional crude oil; can be refined in a petroleum refinery (q.v.)
Tail Gas:
the lightest hydrocarbon gas released from a refining process
Tail Gas Treating Unit (TGTU):
a refinery process unit used to control emissions of sulfur compounds; generally integrated with a sulfur recovery unit
Tar:
the volatile, brown to black, oily, viscous product from the destructive distillation (q.v.) of many bituminous or other organic materials, especially coal; a name used for petroleum in ancient texts
Tar Sand:
see bituminous sand
Thermal Cracking:
a process that decomposes, rearranges, or combines hydrocarbon molecules by the application of heat without the aid of catalysts
Thermal Process:
any refining process that utilizes heat without the aid of a catalyst
Thermal Stability (thermal instability):
the ability (inability) of a liquid to withstand relatively high temperatures for short periods of time without the formation of carbonaceous deposits (sediment or coke)
Toluene (C6H5CH3):
a colorless liquid of the aromatic group of petroleum hydrocarbons made by the catalytic reforming of petroleum naphtha containing methyl cyclohexane; a high octane, gasoline-blending agent, solvent, and chemical intermediate, and a base for TNT (explosive)
Topped Crude:
petroleum that has had volatile constituents removed up to a certain temperature, e.g. 250°C+ (480°F+) topped crude; not always the same as a residuum (q.v.)
Total Acid Number (TAN):
a measure of the acidity determined by the amount of potassium hydroxide in milligrams that is needed to neutralize the acids (typically naphthenic acids) in one gram of oil; used by refineries as an indicator of potential corrosion and scale production
Total Petroleum Hydrocarbons (TPHs):
the total mass of all hydrocarbons in an oil or environmental sample, including the volatile and extractable (non-volatile) hydrocarbons; may be further defined by stating the analytical method used, e.g. GC-detectable TPH or TPH-F (TPH measured by fluorescence), which vary in their rigor
Total Polycyclic Aromatic Hydrocarbons (TPAHs):
including alkyl-PAHs and parent (unsubstituted) PAHs; the sum of all concentrations of PAHs measured by GC-MS
Tower:
equipment for increasing the degree of separation obtained during the distillation of oil in a still
Trace Element:
those elements that occur at very low levels in a given system
Treatment:
any method, technique, or process that changes the physical and/or chemical character of petroleum
Trickle Hydrodesulfurization:
a fixed-bed process for desulfurizing middle distillates
Trillion:
1 × 1012
True Boiling Point (true boiling range):
the boiling point (boiling range) of a crude oil fraction or a crude oil product under standard conditions of temperature and pressure
Unconventional Crude Oils:
petroleum that does not flow readily in the reservoir and/or must be produced by using unconventional methods, such as surface mining of shallow bitumen deposits, steam-assisted gravity drainage (SAGD) for in situ extraction of deep bitumen deposits, cyclic steam injection for heavy oils, or horizontal drilling with hydraulic fracturing for recovery of light
shale oilsUnfinished Oils:
all oils requiring further processing, except those requiring only mechanical blending. Unfinished oils are produced by partial refining of crude oil and include naphtha, kerosene, light gas oils, heavy gas oils, and residuum.
Upgrading:
the conversion of petroleum to value-added salable products; includes hydroprocessing, hydrocracking, fractionation, and any other catalytic or noncatalytic processes that improve the value of the products. During upgrading, the products of the Fischer-Tropsch process are converted to diesel, jet fuel, naphtha, or bases for synthetic lubricants and wax.
Upstream:
a sector of the petroleum industry referring to the searching for, recovery, and production of crude oil and natural gas; also known as the exploration and production sector
Unresolved Complex Mixture (UCM):
petroleum constituents that are not resolved by conventional GC and appear as a ‘hump’ in the gas chromatogram; comprises many hundreds or thousands of unresolved isomers
Vacuum Distillation:
distillation (q.v.) under reduced pressure; distillation under reduced pressure (less than atmospheric) which lowers the boiling temperature of the liquid being distilled. This technique, with its relatively low temperatures, prevents cracking or decomposition of the charge stock.
Vacuum Gas Oil:
a product of vacuum distillation; a preferred feedstock for cracking units to produce gasoline; abbreviated as VGO
Vacuum Residuum:
a residuum (q.v.) obtained by distillation of a crude oil under a vacuum (reduced pressure); that portion of petroleum that boils above a selected temperature, such as 510°C (950°F) or 565°C (1050°F)
VI:
see viscosity index
Visbreaking:
a (relatively) mild process for reducing the viscosity of heavy feedstocks by controlled thermal decomposition; a process designed to reduce residue viscosity by thermal means, but without appreciable coke formation
Viscosity:
a measure of the ability of a liquid to flow or a measure of its resistance to flow; the force required to move a plane surface of 1 m2 area over another parallel plane surface 1 m away at a rate of 1 m/s when both surfaces are immersed in the fluid
Viscosity Index (VI):
an arbitrary scale used to show the magnitude of viscosity changes in lubricating oils with changes in temperature
Volatile Organic Compounds (VOCs):
chemicals having high vapor pressure at room temperature (and corresponding low boiling point) that tend to evaporate or sublimate into the air; for example, BTEX
Water-Accommodated Fraction of Oil (WAF):
hydrocarbons that will partition from oil to water during gentle stirring or mixing; may contain droplets, in contrast to water-soluble fractions (WSF)
Water-Soluble Fraction of Oil (WSF):
aqueous solution of hydrocarbons that partition from oil; does not include droplet or particulate oil; see also CEWAF and HEWAF.
Weathering:
a suite of changes in spilled oil composition and properties brought about by a variety of environmental processes including spreading, evaporation, photo-oxidation, dissolution, emulsification and biodegradation, among others
Wet Gas:
gas containing a relatively high proportion of hydrocarbons that are recoverable as liquids; see also lean gas
Xylene [C6H4(CH3)2]:
a colorless liquid of the aromatic group of hydrocarbons made from the catalytic reforming of certain naphthenic petroleum fractions; used as high-octane motor and aviation gasoline blending agents, solvents, and chemical intermediates; isomers are ortho-xylene (o-xylene), meta-xylene (m-xylene), and para-xylene (p-xylene)
Zeolite:
a crystalline aluminosilicate used as a catalyst and having a particular chemical and physical structure
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