What is oil?
- Oil is a fossil fuel. Most of the oil extracted today has been formed from prehistoric organisms whose remains settled at the bottoms of oceans and lakes millions of years ago.
- Crude oil comes in many forms. Usually it is black, but green, red or brown oils are not uncommon. Thin and volatile oils are called "light", whereas thick and viscous ones are "heavy"
- Oil and gas are found in geological basins that have been filled over tens of millions of years by fragmented material.