What is Oil Sands?
Oil sands’ or ‘tar sands’ are a mixture of sand, clay, and water that contain an extra heavy crude oil variant known as bitumen. Bitumen is highly viscous, meaning it does not flow unless it is heated or mixed with lighter hydrocarbons1. It is often compared to cold molasses.
To extract the bitumen in the oil sands, conventional oil drilling techniques cannot be used because bitumen is too heavy to be pumped and sticks to sand grains. Therefore other extraction techniques have been developed. The most common methods to extract bitumen are open-pit mining and in-situ, which is Latin for ‘in place’.
Bitumen within 75 meters of the surface is open-pit mined. First, huge clumps of oil sands are shoveled into large trucks. They are then taken to crushers, where they are broken down and mixed with heated water to separate the bitumen from the sand. Once the bitumen is released, it is sent for further processing.
Around 80 percent of the oil sands are found 75 meters below the surface; therefore, to extract them, in-situ or underground methods must be used. The majority of the in-situ operations pump steam underground through horizontal wells with the purpose of liquefying the bitumen which can then be pumped up to the surface – a method called Steam Assisted Gravity Drainage (SAGD).
Produced bitumen is heavier than conventional sources and requires a special process called upgrading to give it properties similar to conventional oil. Once processed, bitumen is refined just like conventional oil into common petroleum products.
The two largest oil sands reserves in the world are located in Northern Alberta, Canada and Venezuela2.
The oil sands represent a large supply of potentially recoverable oil and, like all oil, its key advantage is its energy density. The synthetic crude oil created through upgrading bitumen is mostly used to fuel cars, airplanes, and trucks. However, bitumen is also used to create petrochemical products that people use daily, such as artificial limbs, icepacks, soccer balls, medical equipment and even LCD touch screens for laptops and cell phones3. Interestingly bitumen is also used to pave roads and patch holes in canoes.
Oil sands development poses environmental and social challenges. The crude derived from oil sands is more carbon intensive than conventional crude, due to the greenhouse gas emissions associated with its production techniques. Other environmental challenges include heavy water use, which in most cases comes from fresh water sources. Tailings ponds, which are man-made dams for storing wastewater from oil sands mining processes, are problematic because of the contaminants contained in the wastewater. Currently, the water cannot be naturally recycled back into the ecosystem but many companies are exploring technologies to return the water and ponds to their natural states. Land disturbance and use is also a concern for the oil sands, particularly when it comes to mining, as deposits occur in ecologically diverse areas.
Finally, the complexity of extraction techniques used for oil sands production equates to higher production costs than conventional sources of oil.