Unconventional oil is petroleum produced or extracted using techniques other than the conventional (oil well) method.  It consists of a wider variety of liquid sources including oil sands, shale oil, extra heavy oil, gas to liquids and other liquids.  Unconventional oil is a substitute for conventional oil, however it is typically harder and more expensive to produce than conventional oil.

Definitions:

Oil Sands (Tar Sands) – either loose sand or partially consolidated sandstone containing a naturally occurring mixture of sand, clay, and water,saturated with a dense and extremely viscous (thick and sticky) form of petroleum technically referred to as bitumen (or sometimes referred to as tar due to its similar appearance, odor and color).  It is most commonly found in parts of Canada.

Oil Shale – fine-grained sedimentary rock containing kerogen (a solid mixture of organic chemical compounds) from which shale oil, a liquid hydrocarbon, can be produced. The US holds major deposits of oil shale.

Extra Heavy Oil – a type of crude oil characterized by an asphalt-like, dense, thick and sticky nature (similar to molasses), and its asphaltene (very large molecules incorporating roughly 90 percent of the sulfur and metals in the oil) content. It contains impurities such as waxes and carbon residue that have to be removed before being refined. Extra Heavy Oil has an API gravity of less than 10°.