Bitumen is exceptionally difficult to extract, with most processes requiring some level of physical mining as opposed to pump extraction. Bitumen crude is found impregnated in sedimentary rock, much of which is located in Canada. This rock is often referred to as “oil sand” or “tar sand.” The Athabasca oil sands are the largest bitumen deposits in Canada. They are only accessible to surface mining. Venezuela and the United States contain the second and third largest deposits of oil sands respectively. Venezuela’s deposits are less viscous and easier to extract, but their technology is behind that of Canada and the United States, so they actually produce less petroleum from their reserves. If all deposits in Canada are upgraded to crude, it is estimated that the country could supply the rest of the world with oil for roughly 200 years.