What are oil sands?

Oil sands, also called tar sands, are reservoirs of partially biodegraded oil, combined with sand and water. Over thousands of years, oil-eating bacteria destroyed the lighter components of the in-place oil, resulting in reservoirs containing an extremely heavy form of crude oil, called crude bitumen in Canada, or extra-heavy crude oil in Venezuela. These two countries have the world's largest deposits of oil sands.

The largest accumulation of oil sands is located in Canada near the Athabasca River (Figure 1). It represents the second largest oil field in the world with reserves of 170 billion barrels. Much of this oil lies deep underground and is economically non-recoverable except at very high oil prices. (See Video 1.) Development began in the 1960s, but has been sporadic ever since, intensifying when the price of oil increases and/or new technology is developed, and ebbing when price decreases.

Oil sand does not flow like conventional crude oil; it must be mined or heated underground before it can be processed. For the 20% of oil sands that are close enough to the surface to be mined, trucks and mechanical excavators are used to extract the crude. (See Figure 2.) More conventional oil production techniques are used for the deeper oil sands. First, steam is injected to heat the crude so that it will flow, and then it is pumped to the surface. Once the bitumen is extracted, it is processed into higher-value synthetic crude oil and diesel fuel.

In addition to the high cost of development, there are a number of environmental and social issues associated with oil sand developmnet. Extracting this oil requires more energy than conventional drilling and production. Looking at the full process from in-ground extraction to gasoline at the station, the net energy produced is approximately half that for conventional crude oil with associated higher greenhouse gas emissions. Water and chemical use is high, and there have been concerns over contaminated discharges to the environment, although the energy companies developing the sands have aggressive land reclamation projects under way. The developments have also had an impact on the indigenous population, the First Nations people, living in the area. Along with the positives of economic growth and job creation, there have been negatives in the form of hunting and fishing ground impact, wildlife habitat being destroyed, and concern over health risks.

The recent controversy within the United States regarding the proposed Keystone XL pipeline that would transport tar sands oil to Texas for processing has put the Canada tar sands development on the international stage. Environmental groups and other organizations argue that this pipeline will encourage further development, while proponents argue that it is a valuable source of oil that will help keep prices low, displace imports from the middle east and other unstable regions of the world, and create jobs in the US and Canada.

Back To
Fossil Fuels

More Topics

Try an OWOE eTool!