Crude oil: sweet or sour?

Heavy or light, sweet or sour, WTI or Brent – it is all about crude oil.…

Crude oil is usually named after its geographic origin. For example, WTI is an abbreviation of West Texas Intermediate. The well-known Brent grade takes its name from the first letters of the British oil fields Broom, Rannoch, Etive, Ness and Tarbert.

Crude oil is classified by its chemical composition and physical properties. The terminology used includes “sweet” or “sour,” and “light” or “heavy.”

The American Petroleum Institute classifies crude oil by density:

1. Light – light crude with a density above 31.1 °API

2. Medium – density in the range of 22.3 °API – 31.1 °API

3. Heavy – crude with a density below 22.3 °API.

Depending on sulfur content, crude oil is called sweet or sour. This has nothing to do with its taste, but rather with its value for refining.

On international markets, crude oil is divided into generally accepted grades. They allow raw materials from different fields to be grouped by quality and uniformity.

Russian crude is divided into the following grades: Urals, Siberian Light and ESPO. The latter is named after the East Siberia–Pacific Ocean pipeline.

In the UK, the benchmark crude grade is called Brent. It combines oil produced in the North Sea fields between Norway and Scotland (Forties, Ekofisk, Oseberg and the Brent field).

Statfjord – this is the name given to the Norwegian crude grade. Like the British one, it inherited its name from the largest and oldest field in Northern Europe.

Iraq also named its crude after the country's main field – Kirkuk. Iranian crude is named Iran Light and Iran Heavy. Oil produced in USAis divided into WTI and Light Sweet.

The generally recognized international benchmarks for pricing on commodity markets are Light Sweet Crude oil & WTI (for the Western Hemisphere) and Brent (for Europe and OPEC countries).

The price of crude oil depends heavily on its density and sulfur content. The characteristics of the main export grades are given below. These parameters determine the efficiency, route and cost of subsequent refining into the final product. But more on that in our upcoming publications.