Buzz
Oil sands bear a striking resemblance to topsoil, but their dark, earthy hue is due to the bitumen within, which can be processed into synthetic crude oil. AdShooter / Getty ImagesClose your eyes and picture a tar pit. What comes to mind? Many envision a black, molasses-like lake with preserved saber-toothed tigers trapped within its depths.
These naturally forming asphalt seeps-turned-popular tourist sites have existed for thousands of years, as crude oil from deep underground slowly made its way to the surface through cracks and faults. They continue to fascinate scientists, geology enthusiasts, and children alike.
The industrial tar pits, more commonly referred to as oil sands, tar sands, or bituminous sands, have long been a source of fascination for energy corporations. These deposits, often described as 'black gold,' don't flow freely from the earth like oil from a geyser; instead, they are embedded within the sands themselves.
What Are Oil Sands?
Oil sands are a unique form of unconventional petroleum reserve. They are composed of roughly 90% sand, water, and clay, along with about 10% bitumen — a thick, sticky variety of petroleum that is both dense and highly viscous.
These dark, gooey sands resemble topsoil in appearance, becoming thick and sticky when warm, and freezing into a solid mass as hard as concrete when exposed to cold temperatures.
Referring to these deposits as 'tar' pits or 'tar' sands is inaccurate — the substance in question is not tar, but bitumen, a naturally occurring mixture of hydrocarbons. It's a form of petroleum that exists either as a solid or a semi-solid, rather than a liquid.
Unlike conventional oil or petroleum, which exist naturally in liquid form, bitumen must first be extracted from the sand before it can be utilized.
Are There Oil Sands in the United States?
While the U.S. does have oil sand deposits, they are not as abundant or renowned as those in Canada's Alberta province, where the Athabasca oil sands are among the largest in the world.
In the U.S., significant oil sand reserves are primarily located in Utah, especially within the eastern Uinta Basin. These oil sands, which contain bitumen like those in Canada, have been the focus of various commercial extraction and development projects.
Nevertheless, Canada's oil sands industry is much larger than that of the U.S., where challenges such as economic constraints, environmental concerns, and regulatory hurdles hinder growth.
The rise of unconventional oil resources, such as shale oil and tight oil, has gained significant attention in the U.S. energy sector. This surge is primarily driven by breakthroughs in hydraulic fracturing (fracking) technology, which has greatly boosted domestic oil output.
Oil Sands Production
Extracting oil from oil sands is a complicated and energy-demanding procedure. The most commonly used technique is "in-situ" extraction, where steam and solvents are injected underground to heat the bitumen, facilitating its removal.
When the oil sands are found near the surface, a different method called open-pit mining is employed. This approach uses large machinery to remove the top layer of earth, exposing the oil sands beneath.
After the bitumen is extracted, it undergoes several refining steps to separate it from the sand, water, and other contaminants. The bitumen is then processed further to produce synthetic crude oil through additional refining techniques.
While oil sands have played a crucial role in oil production, they also raise environmental concerns due to the energy-intensive nature of their extraction, as well as the potential for habitat destruction, water contamination, and greenhouse gas emissions during both extraction and processing.
A major environmental issue is the carbon dioxide emissions. For every barrel of synthetic crude oil produced from oil sands, about 295 pounds (134 kilograms) of carbon dioxide are released into the atmosphere. To give some context, in 2021, the U.S. consumed about 19.89 million barrels of petroleum per day.
Efforts are underway to create more environmentally friendly methods for extracting oil from oil sands, aiming to reduce the environmental impact of this valuable resource.
The World's Petrol Supply
Over 2 trillion barrels of the world's petroleum is locked in oil sands, though much of it will never be extracted due to its deep location. Oil sands are found across the globe, from Canada to Venezuela and even in the Middle East.
Canada ranks third in the world for the largest crude oil reserves, following Saudi Arabia and Venezuela.
Canada holds a significant total of 171 billion barrels of oil, with about 165 billion barrels categorized as oil sands reserves. This represents roughly 10 percent of the global crude oil reserves. Alberta alone is estimated to contain up to 161 billion barrels of recoverable oil, with even more awaiting extraction as new technologies for retrieval are developed.
So, how do we extract oil from sand? Next, we'll explore the process of extracting bitumen, refining it, and transforming it into everyday products that might surprise you.
Squeezing Oil From Sand
While bitumen is primarily refined into gasoline, jet fuel, and home heating oil, petroleum also contributes to over 3,000 unexpected products: ballpoint pens, lipstick, flying discs, and even T-shirts. But before any of this can happen, the bitumen must first be extracted from the sand and processed.
A line of bitumen runs across Canada.
David Boily/AFP/Getty ImagesThere are several methods for mining bitumen. Shallow reserves, which account for about 20 percent of oil sands, are extracted through surface mining, which involves open-pit excavation [source: Energy Education]. The surface mining process varies slightly by company but typically includes conditioning, separation, and froth treatment.
Conditioning is the first step in separating sand from bitumen, as well as breaking up any large chunks of oil sands. The oil sands are mixed with warm water — called a slurry — and transported via pipeline to an extraction facility. At the facility, the slurry undergoes a separation process where sand settles at the bottom and impure bitumen froth rises to the surface.
The froth is then steamed, de-aerated, and diluted with naphtha (a flammable hydrocarbon mixture) to eliminate any remaining solids and help it flow more easily. The diluted bitumen is processed using inclined plate settlers (IPS) and centrifuges, which further purify the bitumen.
After all these steps, the extraction process is complete.
Bitumen deposits that lie deep beneath the surface cannot be accessed through open-pit mining and are instead extracted using in-situ methods like steam-assisted gravity drainage (SAG-D). In this process, steam is injected into wells within the oil sands, where the heat and pressure separate the bitumen and water from the sand. The bitumen softens from the heat and rises to the surface, while the sand remains undisturbed.
Other in-situ extraction methods include toe-to-heel air injection (THAI), a newer technique that uses both vertical and horizontal air injections into underground wells, and vapor extraction (VAPEX), which is similar to SAG-D, but instead of steam, solvents are injected.
Upgrading Bitumen
Upgrading bitumen, which is a thick and highly viscous form of petroleum, requires a refining process to convert it into lighter, more valuable products such as synthetic crude oil. This is usually done in specialized facilities known as bitumen upgraders.
- Preparation: Bitumen is commonly mixed with a diluent, such as natural gas condensate or naphtha, to lower its viscosity, allowing easier transport and processing. This mixture is referred to as "diluted bitumen" or "dilbit."
- Heating: The diluted bitumen is heated to break down its heavy molecules and reduce viscosity. This can be done in a coker, where the feedstock is thermally cracked under high temperatures.
- Distillation: The heated bitumen is then distilled to separate it into different fractions based on their boiling points. Lighter components like gases, naphtha, and diesel are separated from the heavier ones.
- Hydroprocessing: The remaining heavy fractions are processed in a hydroprocessing unit, where hydrogen is added under high pressure and temperature. This removes impurities like sulfur, nitrogen, and metals while also breaking down heavy hydrocarbons into lighter forms.
- Fractionation: After hydroprocessing, the upgraded bitumen is further separated into different fractions, including synthetic crude oil, diesel, and other valuable products.
- Additional treatments: Depending on the end product requirements, treatments such as desulfurization, de-asphalting, and hydrogenation are applied to improve quality and value.
- Product storage and transportation: The upgraded products are stored and transported to various markets and refineries for further processing or distribution.
Environmental Concerns
Extracting bitumen and converting it into synthetic crude oil is an environmentally taxing process. To produce just one barrel of upgraded synthetic crude oil, it takes between 2 to 4 barrels of water, along with the equivalent amount of natural gas that would be used to heat a home for four days.
Moreover, oil-sands extraction and processing accounted for 81 million metric tons of greenhouse gas emissions in Canada in 2022 [source: SP Global]. This mining activity also threatens rivers and vast forests, including Canada's boreal forest, one of the largest undisturbed ecosystems on the planet.
If that's not alarming enough, Canada's toxic tailings ponds — which contain the heavy metal-rich waste produced during extraction — are so large they can be spotted from space [source: National Observer].
In response to these environmental impacts, Canada has implemented measures requiring oil companies to restore old mining pits and replant trees. However, reducing reliance on fossil fuels would decrease the need for energy-intensive, low-yield mining and help mitigate the environmental damage caused by extraction.
