The oil market is global. But the crude oil has several regional grades, each one slightly different in terms of viscosity and Sulphur content. The major oil trading regions have benchmarks for monitoring the prices of oil commodities:
WTI (USA)
Brent Crude (Europe)
Dubai Crude (Middle East)
Western Canadian Select (Canada)
Bonny Light (Nigeria)
OPEC Reference Basket
Urals (Russia)
Tapis (Singapore)