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How does oil sands mining work? An overview

How does tar sands mining work? An overview

Amidst mounting evidence for their contribution to climate change, our global dependence on fossil fuels such as oil and gas remains steadfast. Oil sands mining operations – a common method of synthetic oil production – continue to operate in various countries across the world.1

Oil sands are a mixture of sand, water and bitumen (oil that is too heavy or thick to flow on its own). Bitumen is so thick that at room temperature it acts much like cold molasses. For that reason, this resource is sometimes called “tar sands,” but that term is incorrect because bitumen and tar (asphalt) are different compounds. “Oil sands” correctly identifies the end product derived from bitumen: crude oil.

Alarmingly, oil sands mining is a strong contender in the oil and gas industry. This is primarily due the vast quantity of potentially recoverable oil the sands offer. In fact, oil sands collectively represent the largest deposit of crude oil on the planet.2

But of course, oil sands mining comes at a great cost. The excavation of oil sands has long been a contentious talking point in countries like Canada. However, the oil industry remains enthusiastic to exploit the resource, even as environmentalists say it will commit the countries concerned to a future of dirty fossil fuels.3

But how does oil sands mining actually work?

Oil Sands Mining: the basics

Oil sands are a mixture of sand, clay, water, and an extra-heavy crude oil called bitumen. Bitumen oil is so viscous (thick) that it is unable to flow on its own. It is helpful to think of bitumen oil as resembling cold molasses.2

The thickness of bitumen oil also means it cannot be extracted from the ground using conventional oil drilling techniques. As such, other methods have been developed to extract the thick, sticky oil from the surrounding sand: surface mining, and in-situ recovery.4

Oil Recovery: surface mining

Surface mining extracts bitumen deposits within 75 metres of the ground surface. This involves clearing the overlying vegetation, and scooping up large volumes of the oily sand into trucks. From here, the oil is transported to ‘crushers’ which break down the large chunks of sand and oil.5

The sandy, oily mix is then sent to an extraction vessel where it is mixed with hot water to separate the bitumen from the sand. The isolated bitumen then goes through an upgrading process, which results in a synthetic crude oil.6

At this stage, the oil is ready to be refined and used to make common petroleum-based products, like gasoline and plastics.6

In situ recovery

However, the majority of Canada’s oil sand deposits are located far deeper than 75 meters underground. In this case, the oil is too deep to be removed via surface mining, and must therefore be extracted in situ (meaning ‘in place’).4

Typically, in situ recovery entails the use of steam: hot steam is pumped down into the ground through a well, heating up the surrounding oil and enabling it to be pumped up to the surface. Next, the water and bitumen are sent to a processing facility to be separated, before the oil is transported away through pipes, and refined.6

In conclusion, oil sands mining is a well-established system within the oil industry. Unfortunately, its continued support in the name of economic benefit inhibits a transition to sustainable energy alternatives. Only by abandoning fossil fuels entirely can we guarantee energy security for future generations.3

References

  1. EIA (2020) Oil and petroleum products explained: where out oil comes from [Online] US Energy Administration Federation [Accessed July 2020].
  2. CAPP (2019) What are the oil sands [Online] CAPP: Canada’s Oil and Natural Gas Producers [Accessed July 2020].
  3. UCS (2016) What Are Tar Sands? [Online] Union of Concerned Scientists [Accessed July 2020].  
  4. Toman, M., Curtright, A.E., and Ortiz, D.S., Darmstadter, J. and Shannon, B. (2008) ‘Oil Sands and Synthetic Crude Oil’ in Unconventional Fossil-Based Fuels [Online] Technical Report.
  5. Zou, C. (2013) ‘Heavy Oil and Bitumen’ in Unconventional Petroleum Geology. Elsevier, pp 307-335.
  6. CAPP (2019) Oil Extraction [Online] CAPP: Canada’s Oil and Natural Gas Producers [Accessed July 2020].
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