While traditional oil drilling operations continue in the Gulf of Mexico, the Middle East, and other sites around the world, some companies are taking advantage of an alternative source of crude oil: oil sands.
Until recently, oil sands were not considered a viable petroleum source because of the cost associated with the process needed to extract the oil from the oil sands material. However, the increase in the costs of oil extracted from traditional sources has made oil sand processing economically comparable to traditional petroleum.
What are Oil Sands?
Oil sands are a geological structure consisting of sand or clay, water, and crude oil. The type of oil found in oil sands is bitumen, so oil sands can also be known as bituminous sands or tar sands. The largest deposits of oil sands are located in Venezuela and Canada.
The largest known oil sands deposit is the Athabasca Oil Sand Deposit located in northeastern Alberta, Canada. The Canadian oil sands are particularly accessible because about 20% of the reserves are located close to the surface, and have depths of 40-60 meters in most locations, allowing for surface mining of the sands material.
Mining Oil Sands
Because oil sands don’t “flow” like traditional crude oil drilled from wells, the collection and processing of oil sands is more analogous to surface mining operations. The oil sands material is mined from the surface and trucked to processing plants.
Alternatively, oil sands processors can increase the viscosity of the material by mixing it with a solvent. In this case, the resulting slurry can be pumped to off-site processing locations through a pipeline many miles long.
Oil Sands Processing
Oil sands are made up of a mixture of solids and liquids, and significant processing is required to extract the bitumen. One of the primary methods of extraction is agitation, where the slurry material is mixed with caustic soda and hot water, then shaken, allowing solids to sink to the bottom of the mixture, and the oil froth to float to the top where it can be skimmed away and purified.
The leftover sand/clay material, called tailings, is further processed using centrifuges to extract more bitumen. Current technology allows for about 90% of the bitumen to be extracted from the raw oil sands material. The leftover material, primarily sand and clay, is returned to locations that had been previously mined for land reclamation. About two tons of raw oil sands are processed to produce one barrel of oil.
Oil sands offer an alternative source of oil from traditional drilling operations. Existing reserves of oil sands could theoretically exceed the known reserves of traditional petroleum, resulting in a consistent and long-term source of oil.
Sources
Performance of High Pressure Slurry Pumps in Oil Sand Tailing Application, Addie, G., Dunens, E. and Mosher, R. 8th International Symposium on Freight Pipelines, September, 1995.
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