A glossary of common terms and abbreviations used in the industry, with links to more in-depth articles on key words
C4 - (butane) one of the lightest liquid streams produced in a refinery. The butane molecule has four carbon atoms and 10 hydrogen atoms
C4= -(butylene) an unsaturated four carbon olefin, basically butane with one double bond
C4 isomerization - a refining process unit that converts normal butane (n-C4) into isobutane to feed the alkylation unit
C5+ - a distillation cut commonly called light straight run naphtha. It is comprised of pentane and slightly heavier material
C5/C6 isomerization - a refining process unit that converts light naphtha into a higher-value gasoline blendstock by changing its molecular shape and raising its octane
Cabinda (crude) - a medium, sweet crude grade produced in Angola
CAFE - (Corporate Average Fuel Economy) the motor vehicle fuel efficiency standard used in the US
Calcineable coke - pet coke of a quality that makes it desirable as feed to a calciner to produce calcined coke
Calcined coke - pet coke that has been processed in a rotary kiln calciner to remove volatiles and make it suitable for forming anodes
Calciner - a plant that treats raw or green coke from a coker to produce coke suitable for anode manufacture
Calendar day (capacity) - a measure of refining capacity adjusting for typical operating conditions that keep average throughput below maximum achievable throughput (stream day capacity)
California air resources board - (CARB) the government agency that regulates air quality in the state of California, in the US
Call on OPEC capacity - an estimate of the crude oil production volume required of OPEC countries to balance the global supply and demand for crude oil
Call option - a contract that allows the buyer to purchase a commodity in the future at a designated price, in exchange for paying a premium
Cambay (crude) - a light, sweet crude grade produced in India
Cap at rack - (CAR) a regulatory program that seeks to reduce emission of carbon from transportation fuels through a cap and trade program applied at the truck rack
Capacity - a measure of maximum possible throughput of a refining process unit
Capital employed - the capital tied up in owning and running a refinery
Capline (pipeline) - a major crude oil pipeline running from the US Midwest to the US Gulf Coast, in the US
CAR - (Cap at rack) a regulatory program that seeks to reduce emission of carbon from transportation fuels through a cap and trade program applied at the truck rack
CARBOB - the standard grade of gasoline supplied to the California market, in the US
CARB - (California air resources board) the government agency that regulates air quality in the state of California in the US
CARB gasoline - the standard grade of gasoline supplied to the California market, in the US
CARB diesel - the specific grade of diesel fuel required in the state of California in the US
Carbon black - a specialty product, comprised of solid carbon in a fine powder form
Carbon capture and storage - (CCS) a CO2 reduction project that captures CO2 from an emission source and pumping it into underground reservoirs
Carbon intensity - (CI) a standardized measure of the carbon emissions associated with a product or activity
Carbon rejection - any chemical process that results in the production of elemental carbon (pet coke) and therefore a reduction in carbon content (rejection) in the liquid hydrocarbons involved
Carbon residue - a measure of the amount of coke residue left when a hydrocarbon stream is completely distilled. It is used as an indicator of the asphaltene content of a stream and a predictor of the coke yield when the stream is fed to a coker or FCC
Cargo - a waterborne shipment of crude or refined product, typically on a oil tanker or barge
Castilla (crude) - a heavy, sour crude grade produced in Colombia
Cat gasoline - the primary product out of the FCC unit. FCC gasoline has approximately the properties required for finished gasoline (octane and vapor pressure)
Cat naphtha - the primary product out of the FCC unit. FCC gasoline has approximately the properties required for finished gasoline (octane and vapor pressure)
Cat slurry - a highly-aromatic resid stream produced by the FCC. Generally used as a fuel oil blendstock or feed to another conversion unit
Cat unit - (FCC) the most common conversion unit used in refining to upgrade heavier distillation cuts to light products
Catalyst - a substance that enhances a chemical reaction without being one of the reactants
Catalytic cracking - (FCC) the most common conversion unit used in refining to upgrade heavier distillation cuts to light products
Catalytic reforming - refinery process unit that upgrades low-octane heavy naphtha to make gasoline that meets minimum octane requirements
Cbob - a common grade of gasoline produced by refiners in the US. When blended with 10% ethanol gives finished conventional 87 gasoline
CCR (process unit) - (Continuous catlyst regneration reformer) a refining process unit that upgrades low-octane heavy naphtha to make gasoline that meets minimum octane requirements
CCR (quality) - (Conradson carbon residue) a measure of the carbon content of a feedstock
CCS - (Carbon capture and storage) a CO2 reduction project that captures CO2 from an emission source and pumping it into underground reservoirs
CCU - (catalytic cracking unit) the most common conversion unit used in refining to upgrade heavier distillation cuts to light products
Centistoke - a measure of crude or refined product's kinematic viscosity
Cetane - a measure of diesel quality, specifically the tendency of diesel fuel to auto-ignite when injected into the combustion chamber of a diesel engine that has been heated by compression of the air in the chamber
Cetane improvers - additives to diesel fuel that, when added at low concentrations, boost the cetane number of the blend
Cetane index - a scale reflecting the degree to which a fuel will auto-ignite under specific operating conditions
Cetane number - an estimation of the Cetane number made using bulk properties (density and distillation profile) without having to employ a test engine
CDU - (crude distillation unit) the first step in the the refining process. The primary purpose of the atmospheric distillation tower is to separate crude oil into its components (or distillation cuts, distillation fractions) for further processing by other processing units
CFPP - (Cold flow plugging point) the lowest temperature at which a fuel will freely flow through filters in an engine
Champion (crude) - a heavy, sweet crude grade produced in Brunei
Characterization factor - a measure of the aromaticity/paraffinicity of a crude oil or of a crude oil fraction
CI - (Carbon intensity) a standardized measure of the carbon emissions associated with a product or activity
CIF - term used to indicate pricing of a cargo of crude or refined product on a delivered basis, which would include the cost of the oil at the origin plus the cost of insurance and freight to deliver the oil to its destination
Cinta (crude) - a medium, sweet crude grade produced in Indonesia
CJ blend (crude) - a medium, sweet crude grade produced in Nigeria
Clarified oil - a highly aromatic resid stream produced by the FCC
Claus unit - a refinery process unit that converts H2S gas into elemental sulfur that can then be sold as a finished product
Clean products - finished refined products such as gasoline and diesel that meet tight quality specifications
Clean product tanker - a ship that is dedicated to moving finished petroleum products so as to maintain their quality
Clear gasoline - a finished gasoline blend that does not contain ethanol
Cloud point - an indicator of the tendency of a diesel fuel to form wax crystals when cold
Coke - the solid carbon byproduct of cracking units such as the the FCC and coker unit
Coke pile - the inventory of pet coke held at a refinery that builds up as coke is removed from the coke drums at the coker
Coke drum - the vessel in the coker facility where pet coke accumulates as the cracking reaction occurs
Coker - A refnery process unit that takes the lowest value bottoms material (vacuum resid) and cracks it to the point that all of the resid is eliminated yielding only lighter fractions and solid carbon (petcoke)
Coker distillate - diesel range material produced by the coker
Coker gasoil - VGO range material produced by the coker. It is typically fed into either the FCC or the hydrocracker
Coker naphtha - naphtha range product from the coker unit
Cold flow properties - a measure of a refined products ability to perform well in cold temperatures (eg pour point, cloud point, cold flow plugging point)
Cold Lake (crude) - a heavy, sour crude grade produced in Western Canada
Colonial (pipeline) - one of the major refined product pipelines that moves gasoline, diesel, and jet fuel from the US Gulf Coast to the US East Coast market
Commercial butane - the lightest liquid stream produced in a refinery. The butane molecule has four carbon atoms and 10 hydrogen atoms
Common carrier (pipeline) - any pipeline that offers transportation services to any third party under a standard set of terms
Complexity - quantitative measure of how much high-value conversion capacity a refinery has installed relative to its distillation capacity
Compression ratio - a measure of the change in volume of a combustion chamber in an internal combustion engine across the combustion cycle
Concarbon - a measure of the amount of coke residue left when a hydrocarbon stream is completely distilled
Condensate - a mixture of light liquid hydrocarbons, similar to a very light (high API) crude oil
Condensate splitter - an atmospheric distillation tower designed specifically to process condensate
Configuration - the combination of process units that the refinery has
Conradson carbon - a measure of the amount of coke residue left when a hydrocarbon stream is completely distilled
Constraint - some physical limitation on the process such as a capacity limit, quality limit, or operating condition limit (temperature, pressure)
Contango - a market conditions where prices of a commodity in the future are higher than current (prompt ) prices
Continuous catalyst regeneration (reformer) - (CCR) refining process unit that upgrades low-octane heavy naphtha to make gasoline that meets minimum octane requirements
Continuous process - a refining process in which processing happens without interruption, as opposed to batch processing
Control room - a room in the refinery where operators can monitor and control operations in the plant
Conversion processes - refining process units used to convert one hydrocarbon stream into another by changing molecule size and structure
Conway - a major hub for processing, storage and trading of NGLs located in Conway, KS in the US
Cooling water - water that is used in a refining to lower the temperature of refining streams and processes
Cooling water tower - a process unit that cools water for use in a refinery through evaporation of some of the water
Co-products - different products that are unavoidably produced simultaneously with each other. This is similar to the concept of by-products except the products are of similar value
Copper strip corrosion - a measure of a crude or refined product's tendency to corrode copper, brass or bronze materials in storage tanks and pipes
Corporate average fuel economy - (CAFE) the motor vehicle fuel efficiency standard used in the US
Cossack (crude) - a light, sweet crude grade produced in Australia
Cost and freight - a standard set of terms for a cargo contract in which the seller pays all shipping costs, except for insurance
Cost, insurance and freight - (CIF) term used to indicate pricing of a cargo of crude or refined product on a delivered basis, which would include the cost of the oil at the origin plus the cost of insurance and freight to deliver the oil to its destination
CPC blend (crude) - a light, sweet crude grade produced in Kazakhstan
Crack - short for crack spread
Crack spread - A measure of refining market conditions based on the difference in price between a refined product and a specific crude grade
Cracked gas - refinery gas coming from cracking units that contains unsaturated molecules such as ethylene, propylene and butylene
Cracked gas plant - the set of units that process refinery gas coming from cracking units
Cracking - a broad term that refers to any process that results in the breaking down of larger hydrocarbon molecules into smaller molecules (eg catalytic cracking, hydrocracking)
Cracking configuration - a medium complexity refining configuration consisting of atmospheric distillation, reforming, hydrotreating, and FCC
Creep - the tendency of refining capacity to gradually increase over time, even without major capital projects
Crude - a naturally occurring mixture of liquid hydrocarbons. In its natural state, crude oil has few direct uses
Crude assay - a detailed chemical analysis of a crude oil that describes the volumes and qualities of different refined products that will result from processing the crude through a refinery
Crude diet - the mix of different crude grades that the refinery is running
Crude grades - specific type of crude oil as it comes out of the field or is blended before sending to the market
Crude oil - a naturally occurring mixture of liquid hydrocarbons. In its natural state, crude oil has few direct uses
Crude qualities - specific properties of a crude grade that affect the yield and quality of refined products that will result from refining it
Crude slate - the mix of different crude grades that the refinery is running
Crude to chemicals - (CTC) a process that allows high or full conversion of crude oil to petrochemical feedstocks and products (as opposed to fuels)
Crude unit - (CDU)the first step in the the refining process. The primary purpose of the atmospheric distillation tower is to separate crude oil into its components (or distillation cuts, distillation fractions) for further processing by other processing units
Cryogenic separation - method used to purify the hydrogen produced by conversion units for subsequent use as a feed stock into hydrocrackers or hydrotreaters
Cumene (unit) - a process unit that converts benzene to cumene
Cumene (product) - a specialty product made from alkylation of benzene with propylene
Cushing - a major crude oil trading, storage and transportation hub located in Oklahoma in the US
Cut - the various output streams that come from a distillation tower
Cut point - the boiling temperature that defines the boundary between two crude oil fractions that are being separated
Cutback asphalt - asphalt that has been diluted to reduce it's flow temperature and make it easier to transport and apply
Cutter stock - any stream that is blended to reduced the viscosity of the resulting blend
CTC - (crude to chemicals) a process that allows high or full conversion of crude oil to petrochemical feedstocks and products (as opposed to fuels)
Cycle (pipeline) - a standard sequence of different batches the pipeline cycles through over a standard period of time
Cycle oil - (LCO) the diesel range product from the FCC unit
Cyclohexane (product) - a specialty refined product comprised of a 6 carbon, saturated ring. Used as a petrochemical feedstock
Cyclohexane (unit) - a process unit that produces cyclohexane by hydrogenating benzene
Cyclone - part of an FCC that separates the catalyst suspended in the product so the catalyst can be sent to the regenerator section where the coke on it can be burned off