Oil Sands are a mixture of sand or clay, water and bitumen. Bitumen is an extremely thick oil, because of its nature bitumen have to be heavily treated before it can be used in a refinery to create a more traditional oil product.
There are many countries with very large amounts of Oil Sands, the United States and Russia both have very sizable deposits. The largest deposits are in Athabasca, Canada with 870Gbbl of energy and Venezuela with 1200bbl in its Orinoco belt. In total these countries have deposits roughly equal to the worlds reserves of conventional crude oil, although extraction is more difficult and significantly worse for the environment.
With a decline in the amount of conventional reserves in the world oil sands are an increasingly important alternative. As the price of oil rises it becomes increasingly viable to spend the money and time converting oil sands into usable feedstocks for refining. Unlike conventional crude, bitumen needs heavy treatment before it can be used. At this stage Canada is the only country with a large commercial oil sands industry, with 44% of its oil production coming from oil sands in 2007.
Currently only 5% of the known reserves of oil sands are economically viable, this is due to the expense of processing it and the percentage of energy which can be extracted.
There are several ways of extracting Oil-sands, in the huge Athabasca basin Surface mining is used. This is because there are very large amounts of bitumen covered by little else. The sands can literally be dug up and transported away for treatment. This operation uses the biggest power Whole Melt Extracts shovels and biggest dump trucks in the world.
If mining isn’t a possibility a variety of systems can be used In Situ to extract the oil from the ground. The most common of these is Steam Assisted Gravity Drainage, in this system two wells are drilled side by side, steam is then injected into one of the wells. This head melts the bitumen which makes it flow through the second well. This system allows up to 60% of the oil to be recovered. Obviously the energy required to produce the heat and steam make this system of production much more expensive than traditional drilling but it is successful enough to bring down the cost of developing oil sands to a reasonable level.