What are Oil Sands?
Oil sands, also known as "tar sands," are sediments or sedimentary rocks composed of sand,
clay minerals, water and bitumen. The oil is in the form of bitumen, a very heavy liquid or sticky black
solid with a low melting temperature. Bitumen typically makes up about 5 to 15% of the deposit.
How is the Oil Removed?
The method used to extract bitumen from an oil sand depends upon how deeply the oil sand is buried.
If the oil sand is deeply buried wells must be drilled to extract the bitumen. If the oil sand is
close to the surface it will be mined and hauled to a processing plant for extraction.
Are Oil Sands a Significant Resource?
Most of the world's oil sand resources are located in Alberta, Canada. The Alberta Energy
and Utility Board estimates that these contain about 1.6 trillion barrels of oil - about 14% of all of the world's total oil resource. The largest deposit is the Athabasca Oil Sands (1).
At an oil sands mine the overburden is stripped away and large mining machines load the sand into
trucks that haul it to a nearby processing plant. At the processing plant the oil sand is crushed
and then treated with hot water and chemicals to liberate the bitumen. The liberated bitumen is then
separated from the water, blended with lighter hydrocarbons to reduce its viscosity, and pumped
through a pipeline to a refinery.
Production by Drilling
Bitumen is removed from deeply buried oil sands by drilling wells - a process known as "in-situ recovery".
Several wells are drilled down into the oil sand. Then steam and chemicals are pumped down one well. The hot
steam and chemicals soften the bitumen, reduce its viscosity and flush it to extraction wells where it
is pumped to the surface. At the surface the bitumen is cleaned, blended with lighter hydrocarbons and
pumped through a pipeline to a refinery.
History of Oil Sands Development
Oil sands research began in Canada in the 1920's. The Alberta Research Council
sponsored early research on separating bitumen from oil sands. Experimentation
continued through the 1960's without significant commercial production. Then in
1967 The Great Canadian Oil Sands Company began commercial production, producing
about 12,000 barrels per day.
In the United States, government agencies gave oil companies permits to open
demonstration mines and conduct in-situ drilling on government land in the 1930's.
These projects resulted in minor amounts of commercial production in California
and Utah. However, most were unsuccessful because they were challenged
by remote locations, difficult topography, and a lack of water.
The Athabasca Oil Sands of Canada have been the main source of commercial production.
The surface-mined deposits there can be successful when oil prices are high but in
financial trouble when oil prices fall. They are also challenged by environmental
concerns which include: air quality, land use, and water availability.
Oil sands mining and processing have a number of environmental impacts. These include: greenhouse gas emissions, land
disturbance, destruction of wildlife habitat and degradation of local water quality. In the United States the water
concerns are especially important because the known oil sands and oil shale deposits are located in arid areas of Utah. Several barrels of
water are required for each barrel of oil produced.
Contributor: Hobart King
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| Oil sands mining complex along the Athabasca River in Alberta, Canada. The Athabasca Oil Sands are the largest oil sands deposit in the world. It is the second largest accumulation of oil in the world after Saudi Arabia. Image by NASA / Earth Observatory. Enlarge image.|
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