Oil sands
Oil sands are an unconventional petroleum resource that consists of a mixture of sand, clay, water, and a viscous type of crude oil known as bitumen. The largest reserves of oil sands are found in Canada, particularly along the Athabasca River, making it the global leader in oil sands production. While oil sands represent a significant portion of the world's oil supply, many deposits are not currently profitable to extract due to the complexities and high costs associated with the recovery processes. Extraction methods vary; surface mining is used for deposits near the surface, while deeper deposits require in situ techniques that include steam injection to reduce bitumen viscosity.
The environmental implications of oil sands extraction are a subject of concern, including greenhouse gas emissions, habitat disruption, and potential health risks to surrounding communities and wildlife. Efforts are being made to address these issues, such as the development of carbon capture and storage technologies aimed at mitigating emissions. Despite the challenges, rising global oil prices may enhance the economic viability of oil sands production in the future. Understanding these dynamics is crucial for grasping the complexities surrounding oil sands as both a resource and an environmental concern.
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Oil sands
Summary: Oil sands are an unconventional petroleum resource that contains a viscous type of crude oil known as bitumen, which is refined into crude oil and fuels. Canada is home to the world’s largest oil sands reserves, as well as the only large-scale commercial production.
Oil sands are a naturally occurring fossil fuel composed of sand, clay, various minerals, water, and bitumen. Bitumen is a type of crude oil or petroleum known for its heavy viscosity. Oil sands are sometimes mistakenly referred to as tar sands, a synthetic substance similar in appearance, but with different uses. Tar sands do not have potential as usable fuel sources. Oil sands represent much of the global supply of oil deposits, although not all of it can be profitably recovered at present. The World Energy Council (WEC) lists oil sands and natural bitumen reserves in over twenty countries; the largest are found in Canada, Venezuela, Russia, Kazakhstan, the Middle East, and the US state of Utah.
Utilization of natural bitumen dates back to ancient times, but the first recorded oil sands mining operation dates to 1745. Canadian scientist Dr. Karl A. Clark patented the hot-water-based extraction process underlying modern oil sands recovery technology. Canada is the global leader in the oil sands industry. Canada holds the world’s largest recoverable deposits, estimated at approximately 170 billion barrels. The largest deposits are found along the Athabasca River, while smaller deposits are found in Cold Lake and along the Peace River. Acknowledgement of oil sands as global oil reserves moved Canada to second behind Saudi Arabia in terms of proven reserves. Smaller scale production occurs in Venezuela.
The growth of the oil sands industry has been limited by the difficulty, expense, and environmental concerns of extraction. Oil is more difficult to extract from oil sands and is recovered through mining or in situ production methods. Recovered bitumen then requires additional treatment to make it transportable via pipeline and to refine it into crude oil and from crude oil into fuels. Rising conventional oil prices may make oil sands production more economical in the future. Environmental concerns linked to the oil sands industry include greenhouse gas emissions, land use impacts, pollution, loss of habitat, and threats to animal and human health.
Oil extraction from oil sands requires more complex recovery operations than oil extractions from more conventional oil deposits, as it cannot simply be pumped from the ground. Oil sands deposits that lay near the surface are extracted through strip or open-pit mining techniques. Heated water is used to separate out the bitumen, with the water and other residual materials such as sand and clay discharged into tailings ponds. Materials left after extraction, such as sand, are returned, allowing for later mine reclamation. Over 80 percent of global oil sands deposits cannot be profitably extracted through mining using current technology.
Deposits lying too far below the surface to be mined are extracted instead through various in situ drillable production methods based largely on steam or solvent injection methods or firefloods. Examples of more developed techniques include cyclic steam simulation (CSS), steam assisted gravity drainage (SAGD), and cold heavy oil production with sand (CHOPS); while vapor extraction process (VAPEX), toe to heel air injection (THAI), and combustion overhead gravity drainage (COGD) are newer, more experimental methods. The injection of steam, solvents, or heated air allows the bitumen to flow into oil wells by reducing its viscosity.
Bitumen is diluted with hydrocarbons or chemically split to ensure flow through pipelines to production facilities. Next, the bitumen is separated and processed into heavy crude oil, using a hot water process similar to mining production to remove water, sand, and minerals. The bitumen recovery rate is approximately 75 percent. Finally, it is refined into fuels such as gasoline or diesel. The technological difficulty of extracting and processing oil sands means that approximately two tons of oil sands are required to produce just one barrel of oil. Rising environmental concerns have also made the oil sands industry vulnerable to environmental controversy and legislative requirements governing such issues as greenhouse gas emissions and land reclamation.
Sites must be cleared of forest and vegetative growth, as well as the top layer of peat and soil, prior to extraction. Those in favor of oil sands production note that the disturbed land in places such as Canada is only a small portion of total land and that much of that land will be reclaimed after extraction. Habitat concerns center on reports of deaths and deformities among nearby animal and aquatic life, while human health concerns center on toxic byproducts and potential cancers or other ailments. Greenhouse gas emissions associated with bitumen and synthetic crude oil production are higher than those for more conventional types of fossil fuel production. Oil sands also require large amounts of water and steam, some of which can be recycled.
In 2023, Canadian oil companies and the Canadian government reached an agreement on the construction of a carbon capture and storage (CCS) facility in Alberta, Canada, in an effort to offset the greenhouse gas emissions that come as a byproduct of harvesting the Canadian oil sands. CCS technology aims to reduce carbon emissions by capturing the carbon dioxide that is created through various methods of industry and storing it in underground rock formations. However, a research firm's 2024 report cast doubt on the profitability of the venture, which had been expected to store 1.1 billion liquid tonnes of CO2.
Bibliography
Godkin, David, and Debra K. Rubin. "Risks Ahead for $12B Alberta Oil Sands Carbon Capture Project." Engineering News-Record, 27 Feb. 2024, www.enr.com/articles/58205-risks-ahead-for-12b-alberta-oil-sands-carbon-capture-project. Accessed 6 Aug. 2024.
Government of Alberta Energy. “Oil Sands--Overview.” www.alberta.ca/oil-sands-overview.
Maugeri, Leonardo. The Age of Oil: The Mythology, History, and Future of the World’s Most Controversial Resource. Westport, CT: Praeger, 2006.
Williams, Nia. "Canada Oil Sands Producers to Begin Evaluating Proposed Carbon Storage Site." Yahoo! News, 4 Jan. 2023, news.yahoo.com/canada-oil-sands-producers-begin-174842145.html. Accessed 9 Jan. 2023.