A glossary of common terms and abbreviations used in the industry, with links to more in-depth articles on key words
D-3 RIN - A credit under the renewable fuel standard that is generated through blending of cellusic ethanol
D-4 RIN - A credit under the renewable fuel standard that is generated through blending of bio-based diesel (biodiesel or renewable diesel)
D-5 RIN - A credit under the renewable fuel standard that is generated through blending of a variety of advanced biofuels (eg sugar cane ethanol, biodiesel)
D-6 RIN - A credit under the renewable fuel standard that is generated through blending of any type of bio-based fuel including corn ethanol
D-7 RIN - A credit under the renewable fuel standard that is generated through blending of cellusic-based fuel other than ethanol
Dalia (crude) - a heavy, sweet crude grade produced in Angola
DAO - (Deasphlated oil) the product of solvent de-asphalting of vacuum resid
Daqing (crude) - a medium, sweet crude grade produced in China
Dar (crude) - a heavy, sweet crude grade produced in Sudan
Das (crude) - a light, sour crude grade produced in UAE
Dated Brent - a contract for delivery of a physical cargo of Brent (or a substituable grade) on a given date
DCU - (delayed coking unit) refinery 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)
DDGS - (distiller's dried grains with solubles) the solid by product of ethanol production from corn. It is a nutrient rich and used as a feed for livestock
DEA - (diethanolamine) a common process chemical used to extract H2S gas from refinery gas streams in the amine or girbotol unit
Deadweight ton - (DWT) a measure of the weight (or displacement) of everything that a ship is carrying
Deasphalting - refinery process unit that removes asphaltenes from vacuum resid, producing an asphalt product and a resid that can be used for baseoil manufacturing or cracker feed
De-asphalted oil - (DAO) the product of solvent de-asphalting of vacuum resid
De-butanizer - refinery unit that takes bottoms from the de-ethanizer and separates propane and butane from naphtha based on boiling points
Decant oil - a highly aromatic resid stream produced by the FCC
Decoking - the process of removing coke that has has accumulated in coke drums in the coking unit
De-ethanizer - refinery units that separates methane and ethane from the heavier NGL components, which are absorbed into a naphtha stream (lean oil) to form fat oil
De-isobutanizer - refinery process unit where butane stream from the de-propanizer is further fractionated in a (very tall) column to separate normal butane from isobutane
Dehydrogenation - hydrogen is removed, typically resulting in an olefin
Delaware Basin - a major crude producing region in West Texas and Eastern New Mexico in the US
Delayed coker - (DCU) refinery 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)
Demex - another name for SDA, a refinery process unit that removes asphaltenes from vacuum resid, producing an asphalt product and a resid that can be used for baseoil manufacturing or cracker feed
Demurrage - extra charges levied on the charterer of a vessel when the vessel is kept waiting
Denatured ethanol - ethyl alcohol (ethanol) that has been mixed with a small amount of denaturing agent (typically methanol) to make it unfit for human consumption
Density - the weight of a commodity per unit of volume
De-propanizer - a refinery process unit in which the mixed propane/butane stream from the de-butanizer is sent to a second fractionation tower to separate propane from butane based on boiling points
Desalter - a refinery process unit in which salt is removed from crude oil before being fed to the atmospheric distillation tower
Design capacity - The planned capacity when a plant or unit was designed and constructed. Actual capacity could be higher or lower
Dewatering - the process of removing water from crude oil before it is charged to teh atmospheric distillation tower
Dewaxing - the process of removing wax from baseoil feedstocks before further processing into lubricants
DHT - (Distillate Hydrotreater) one category of hydrotreaters that treats distillate streams from atmospheric distillation and from conversion units to reduce their sulfur content and to improve their properties for blending into diesel
DI - (Driveability Index) a measure of a gasoline's performance across a number of operating conditions, covering cold start and warmed up operations
Diene - a hydrocarbon molecule with two double bonds, for example butadiene.
Diesel - one of the major petroleum products produced from processing crude oil in a petroleum refinery
Diethanolamine - (DEA) a common chemical used to extract H2S gas from refinery gas streams in the amine or girbotol unit
Dilbit - a crude blend made by combining produced bitumen with a diluent such as light naphtha
Diluent - any commodity that is blended into extra heavy crude to reduce its viscosity and allow it to be transported
Dimate - a high-octane gasoline blend stock produced in the dimerization unit from propylene
Dimerization unit - a form of polymerization that converts propylene into a gasoline blend stock by joining two propylene molecules to form one C6 olefin called dimate
Dimersol - a form of polymerization that converts propylene into a gasoline blend stock by joining two propylene molecules to form one C6 olefin called dimate
Diolefin - a hydrocarbon molecule with two double bonds, for example butadiene
Dirty tanker - an oil tanker used to transport crude oil or other black oils such as residual fuel oil
Distillate - a term used to refer both to the atmospheric gasoil cut from atmospheric distillation, and to a range of light products ranging from kerosene to diesel
Distillate hydrotreater - (DHT) one category of hydrotreaters that treats distillate streams from atmospheric distillation and from conversion units to reduce their sulfur content and to improve their properties for blending into diesel
Distillation - 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
Distillation curve - a graph showing the cumulative volume of a crude (or other hydrocarbon stream) that boils off at different temperatures
Distillation cuts - the output streams from a distillation tower
Distillation profile - a description of how much of a hydrocarbon mixture vaporizes at different temperatures
Djeno (crude) - a heavy, sweet crude grade produced in Republic of Congo
Doba (crude) - a heavy, sweet crude grade produced in Chad
DOE - the US federal agency responsible for energy policy.
Domestic sweet (crude) - (DSW) another term for light sweet crude at the Cushing hub and used to fulfill the NYMEX crude contract
DON - a measure of gasoline octane that attempts to capture both the measure of research octane and motor octane in one number
Dos Bocas - a major crude loading port in Mexico and FOB pricing point for Maya crude
Downstream - the part of the petroleum value chain where crude oil is converted into marketable finished products
Draft - the distance below the water surface that a tankers hull reaches
Driveability index - (DI) a measure of a gasoline's performance across a number of operating conditions, covering cold start and warmed up operations
Driving season - summer in the Northern Hemisphere when demand for gasoline is typically at its seasonal peak
Dry gas - natural gas that contains little or no NGLs
DSW (crude) - (Domestic sweet) a blend of light sweet crude oil produced in the interior of the US and used to fulfill the NYMEX crude contract
Dubai (crude) - a medium, sour crude grade produced in the United Arab Emirates
DUC (crude) - a medium, sweet crude grade produced in Denmark
Duri (crude) - a heavy, sweet crude grade produced in Indonesia
DWT - (Dead-weight ton) a measure of the weight (or displacement) of everything that a ship is carrying