Oil sands

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Oil sands are a naturally occuring combination of clay, sand, water and bitumen. Bitumen is a fossil fuel that is separated from the rest of the oil sand to eventually become synthetic crude. It is very thick at room temperature and can not be extracted from the ground unless it is diluted or heated to reduce it's viscosity.

Background

Oil sand deposits are found in about 70 countries throughout the world, with the largest reserves and majority of the industry located in Canada. Some bitumen is found about 200 feet under Earth’s surface, but the majority of it is found much deeper underground. Oil sands that are located near Earth’s surface can be mined using open-pit techniques, but oil sands that are deeper in the ground are mined through steam-assisted methods called in situ techniques. [1]. On average, mined oil sand contains about 10-12 percent bitumen, 4-6 percent water, and 80-85 percent mineral water and clay [1]. Roughly 75 percent of the bitumen from an oil sand is recovered each time. An estimated two tons of oil sands are required to produce one barrel of oil. After oil extraction, the sand and other materials that are not needed are returned to the mine and eventually reclaimed. [2].

History

The first pilot plant for processing oil sands was constructed in Alberta, Canada in 1962. Between 1964 and 1967, the first full-scale oil sand facility was developed, with an initial processing of approximately 31,000 barrels per day. In 1985, the first commercial in situ extraction project was formed. Imperial Oil was the first company to utilize in situ extraction methods, which have significantly increased the production of bitumen [3]. In the 1990’s, the mining and processing of Alberta’s oil sands were significantly increased due to large investments made in the industry. Today, about 97 percent of Canada’s total oil reserves are derived from oil sands. Oil sands cover about 140,000 square kilometers of land, which averages out to roughly the size of Florida. In 2012, oil sands extraction produced about $91 billion towards Canada's gross domestic product [4].

Extraction methods

Oil sands found close to Earth’s surface, specifically within 250 feet, can be mined through a process called surface mining. Oil sands that are found deeper than 250 feet below the surface are mined through in situ extraction methods.

An oil sands Heavy Hauler from Suncor Energy.

Surface mining

About 20 percent of the world’s oil sands are located close to the surface. In surface mining, large hydraulic and electrically powered shovels are used to dig up oil sands from the ground and load them into trucks. These trucks can typically hold up to 320 tons of oil sands per load. These trucks transport the sand to crushers that remove rocks and break down clumps in the oil sands. Next, the oil sands are sent through pipes to the extraction plant. Hot water is added to the oil sands, which causes the bitumen to separate from the rest of the contents. This process is called hydro transport [5].

In Situ extraction

About eighty percent of oil sands are located deeper than 250 feet below the surface. In this scenario, a process called In situ extraction is implemented. In situ extraction requires a number of wells, with depths of up to 1,300 feet, to be drilled into the ground. From there, two different types of in situ extraction methods can be used, including steam-assisted gravity drainage (SAGD) and cyclic steam stimulation (CSS). During SAGD, steam is injected into a horizontal well, which sends heat to the bitumen to reduce its viscosity. With reduced viscosity, the bitumen is forced by gravity to flow to another horizontal well, and eventually make its way to the surface [6]. In CCS, high-pressure steam is injected into a vertical well and is transported down to the bitumen. The steam soaks through the oil sands, reducing the bitumen’s viscosity so that it can flow freely to a producing well and eventually be pumped to the surface. CCS in situ recovery is not as common as SAGD [7].

Upgrading

After bitumen is extracted, it is then "upgraded" into synthetic crude oil (SCO). Currently, about 60 percent of bitumen is upgraded in facilities located in Canada, specifically Fort McMurray and Edmonton. Once bitumen is upgraded into SCO, it can then be refined into products such as gasoline, fuel oil, ethylene, and propylene [8]

See also

Other closely related articles in this wiki include:

References

  1. 1.0 1.1 Freedman, B. (2011).Tar Sands.
  2. OSTEIS. (2012).Tar Sands Basics
  3. Regional Aquatics Monitoring Program. (n.d.). History of the Oil Sands
  4. Davidsen, C. (2015). Oil Sands
  5. Oil Sands Fact Check. (2012).What Are Oil Sands?
  6. Alberta Energy Regulator. (2016). In Situ Impacts.
  7. Regional Aquatics Monitoring Program. (n.d.) In Situ Methods used in the Oil Sands.
  8. Institute for Oilsands Innovation. (2016). Oil Sands History and Development.


External links

Relevant online sources to this wiki article include: