The stages of this earthcache can be completed in any order. If you are completing the WESTCAN6 geoart, your route will take you to each stage without needing to detour. Please do not post photos with your log and do not block the entrances at waypoints 2 and 3.
Geology
The “Alberta Oil Sands” are a series of oil sand deposits in the northern half of Alberta. There are three principal deposits, each named for a major nearby waterway. In descending order of size, they are known as the Athabasca (40,000 km2), Cold Lake (22,000 km2), and Peace River (8,000 km2) deposits, and collectively underlie an area roughly the size of New Brunswick.
Oil sand is a naturally occurring mixture of sand, clay, and water, which has been saturated by a dense, viscous fluid known as bitumen (“heavy oil”). A typical “handful” of oil sand is composed of approximately 11% bitumen, 5% water, and 84% minerals. Oil sand is hydrophilic, meaning the grains of sand are surrounded by a film of water, which is itself surrounded by bitumen. The largest oil sand deposits in the world are situated in Canada, Russia, and Venezuela, with northern Alberta accounting for the largest proven reserve in the world.
Bitumen is a dark, tar-like substance that can be refined to produce commercially viable fuels at a rate of about 2 tonnes of oil sand for every barrel (159 L) of synthetic crude oil. (This visual similarity has given rise to the misnomer of calling the oil sands, “tar sands”. Bitumen is a natural substance; tar is artificial.) It is too thick, and the sand mixture too saturated, for traditional oil extraction methods. Whereas crude oil is pumped out of the ground as a liquid, bitumen more closely resembles cold molasses and cannot flow in its natural form. This requires the use of less traditional methods of oil extraction, which will be discussed later.
The origin of the Alberta Oil Sands is a matter of some dispute. The leading hypotheses describe bitumen as a “successor” petroleum product, having developed from earlier deposits of either crude oil or cretaceous shales. The first hypothesis asserts that crude oil was converted to bitumen through microbiological breakdown; the second, that bitumen was forced out of oil-rich shales through underground pressure (possibly due to the uplift of the Rocky Mountains to the west) into existing silt and sand deposits. The oil itself formed over millions of years of organisms dying, decomposing, and getting squeezed by intense heat and pressure.
Extraction
In sites where the oil sand is close to the surface (i.e. <70 m below ground), it is accessed by clearing forests and scraping away the soil, rocks, and organic matter (collectively, “overburden”) in expansive open-pit mines. This technique is sometimes used in oil sand deposits further north (centred around Fort McMurray), but you won’t see any of that in the Cold Lake area. The oil sand here is 300-600 m below ground, so the bitumen must be extracted through the use of in situ technology.
In situ (Latin for “in position” or “on site”) technology serves to overcome two distinct challenges: 1) reducing the bitumen’s viscosity so it can flow, and 2) recovering it from deep underground. Two main processes may be utilized in this endeavour: Cyclic Steam Stimulation (CSS) and Steam-Assisted Gravity Drainage (SAGD), both of which use high-intensity steam to “melt” the oil sand to a viscosity at which it can flow. CSS employs a single vertical well and steams the oil sand at more than 300°C. After enough has melted and flowed, the steam is halted and the melted oil sand is pumped to the surface. This cycle can take 4-24 months to complete. SAGD employs two parallel horizontal wells deep underground. The upper well steams the oil sand, which flows down to the lower well and is continuously pumped back to the surface.
Processing
In order to convert raw oil sand into usable petroleum products, it must first be upgraded to crude oil, and then refined into commercial products such as gasoline or kerosene. Once at the surface, the melted oil sand is treated to separate the hydrophobic (water-repelling) bitumen from the hydrophilic sand and clay. Hot water is added to form a very thick liquid mixture called slurry. The slurry is sent to a separation vessel, where the frothy bitumen floats to the top, leaving sand and clay at the bottom, with water in between. The frothy bitumen is skimmed from the top and sent to large storage tanks, where it is chemically treated to further remove water and minerals from the heavy oil. From here, the bitumen may be upgraded by coking, where it is heated to nearly 500°C to break down into lighter fractions, or by hydro-processing, where hydrogen is added so as to bond with the carbon. This upgraded, lighter oil is the final product produced in the Cold Lake area; from here it is transported to Edmonton or elsewhere to be refined into commercially viable fuels.
The sand and clay recovered from oil sand may be used in a variety of projects on the surface, including building dikes and tailing ponds. The tailing ponds, which are only needed in areas that use open-pit extraction techniques, are used to hold water consumed in the upgrading process; the minerals in the water settle over time, allowing clear water to be recycled for use in future bitumen upgrading. Interestingly, 1.0 m3 of extracted oil sand produces 1.4 m3 of sand and clay on the surface, because the minerals do not re-consolidate the way they did underground.
Sources
- Beauchamp, Matt. Absolute Combustion – Heating up the Oil Extraction Process. September 3, 2015. https://theogm.com/2015/09/03/absolute-combustion-heating-up-the-oil-extraction-process
- Government of Alberta. Oil Sands Discovery Centre: Facts about Alberta’s oil sand and its industry. 2009. https://open.alberta.ca/dataset/d5a7fec7-6e37-431c-9f33-eb98510c65e4/resource/eb20740d-d1bc-4e60-b441-99f6c84998d8/download/2016-oil-sands-discovery-centre-osdc-facts-about-albertas-oil-sands-and-its-industry.pdf
- http://www.ems.psu.edu/~pisupati/ACSOutreach/Oil_Sands.html
- http://www.thecanadianencyclopedia.ca/en/article/bitumen/
- http://history.alberta.ca/energyheritage/sands/underground-developments/in-situ-development/cold-lake.aspx
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To log this earthcache as found, first e-mail me the answers to the following questions (don’t post them in your log!). You may log it as found without hearing a response from me, but e-mails with missing or poor answers may be deleted, and the cacher notified as to the reason(s) why.
1. After the slurry has been processed, it is treated with naphtha to remove additional water and minerals in large tanks. From the posted coordinates, tell me how many total large tanks you see on the south side of the road. Tell me their colour and shape as well.
2. Waypoint #2 brings you to the entrance of a facility on the north side of the road, which you don’t need to enter. What is the name of this facility, and how might the byproducts of bitumen extraction (water, sand, or clay) be of use here?
3. Waypoint #3 brings you to the entrance of another facility on the west side of the road, which you also don’t need to enter. What is the name of this facility, and do you think bituminous product is brought here before or after it has undergone coking/hydro-processing? Why?
FTF: NNVN
Congratulations to 0011mixam for finding your 4,000th cache!