HDPE
High-density polyethylene. Used in the manufacture of plastic items, such as plastic pipe, grocery bags, water coolers and milk bottles.

Heavy Bottoms
Thick, black substances that remain in refinery stills after all lighter fractions have been processed out of the feedstock.

Heavy Crude
Crude oil of 20 degree API gravity or less; often very thick and viscous.

Hexane
A petroleum liquid found in small amounts in condensates; one of the components of natural gasoline.

Hexene-1
A key feedstock in the manufacture of many high-density and linear low-density polyethylene resins, which are used to make food and drink containers, trash bags, plastic pipe and other consumer products.

Horizontal Drilling
The technique for cutting a hole in geological strata in a horizontal, rather than the normal vertical, direction.

Hydrocarbons
Organic chemical compounds of hydrogen and carbon atoms that form the basis of all petroleum products. They may exist as solids, liquids or gases.

Hydrotreating
A refinery process to remove sulfur and nitrogen from crude oil and other feedstocks.