Material World: The Six Raw Materials That Shape Modern Civilization

by Ed Conway

The oil coming out of Ghawar, for instance, is sometimes called “Arabian light”: light because it is less viscous and dense than, say, heavy, gloopy Venezuelan Merey crude or Maya crude from Mexico. And since you can pump lighter oil out of the ground more easily, Saudi oil—at least the stuff they have onshore—needs considerably less work and expense to pump and refine than most other oils around the world. Oils can also be “sweet” or “sour”—a measure of sulphur content, which dates back to the early days when crude was mostly used for indoor lighting. Too much sulphur in your kerosene and not only was there a noxious smell when it burned, it would also tarnish the silver in your lamp. Back then the quickest way to test for this before burning was to give it a quick taste—the more sulphur, the more sour it was—and this shorthand has stuck. Broadly speaking, the less heavy and sour an oil is, the less time and effort refineries have to put into processing it, so lighter and sweeter crudes usually fetch a higher price.