Frequently Asked Questions about Direct Contact Steam Generation
1) Why is Canadian oil so popular/important?
Canada is regarded as having the third largest oil reserves in the world, behind only Venezuela and Saudi Arabia. Alberta provides over 15% of Canada’s GDP and almost a third of that is from resource extraction.
2) Where does Canadian oil come from?
Alberta, Saskatchewan, and the off-shore reserves of Newfoundland and Labrador produce the majority of crude oil in Canada. The Alberta Oil Sands are responsible for over 80% of the crude oil that comes from Canada.
3) What is oil sand?
Oil sand is composed of deposits of sand, clay, sandstone and/or other sedimentary rocks that contain crude bitumen.
4) What is bitumen?
Bitumen is a heavy, viscous substance that is essentially a mixture of hydrocarbons. The majority of Canadian oil is in the form of bitumen.
5) How is bitumen extracted?
There are essentially two techniques used in the oil sands industry to obtain oil from a reservoir:
- Surface mining is a common approach when extracting from shallow oil sand deposits.
- Other wells are too deep and therefore require “in situ” extraction, which involves thermal stimulation of oil reservoirs to reduce the viscosity of crude bitumen. Two in situ methods are Cyclic Steam Stimulation (CSS) and Steam Assisted Gravity Drainage (SAGD). Roughly 81% of Canadian oil sands reserves are considered too deep to be mined.
6) What are the issues with oil sands extraction?
The extraction of bitumen is more energy intensive than that of conventional crude oil, due to the energy required to produce the steam that is used to thermally stimulate the bitumen reservoir. Producing that steam also requires large quantities of fresh water, at a rate of 0.4 barrels of fresh water per barrel of oil extracted. Another outcome of the bitumen extraction process is wet tailings. Wet tailings are the remains of the extraction process and are made up of waste water, from the steam injected into the wells for bitumen recovery through SAGD, as well as other contaminants.
7) What does CSS stand for?
CSS stands for 'Cyclic Steam Stimulation'. CSS involves drilling one well and then alternating between steam injection and oil extraction. Thanks to the adoption of SAGD methods, CSS techniques are becoming less common over time.
8) What does SAGD stand for?
SAGD stands for 'Steam Assisted Gravity Drainage' and involves using two parallel horizontal wells, one positioned above the other. The upper well (injection well) works as a steam chamber and is used to continually inject steam into the ground. As temperature rises in the oil sand formation, bitumen becomes more fluid, and due to gravity, flows to the lower well (production well). Finally, the condensed water and crude oil or bitumen is pumped to the surface and transported to an upgrader facility.
9) What does DCSG stand for?
DCSG stands for 'Direct Contact Steam Generation'. This innovative technology is enhancing typical SAGD methods by providing a new way to generate steam for the extraction process.
10) How does DCSG technology improve current SAGD methods?
Currently, the most common method of steam generation for SAGD is through the use of conventional boilers. Conventional boilers generate steam by heating water that flows through a collection of pipes inside the boilers. Conventional boilers generate steam by heating water that flows through a collection of tubes inside the boiler. Heat is produced by burning fuel, which produces greenhouse gas emissions (GHGs), principally CO2. Flue gases from the boilers must also be treated to remove pollutants. Additionally, the water used to generate steam must be very clean in order to avoid contaminant build up and plugging of the boiler tubes. These extra processes require large amounts of energy, consequently increasing GHG production, and reducing the system’s overall efficiency.
DCSG presents a novel approach to generating steam by injecting the water directly into the combustion chamber and injecting the high pressure steam and CO2-rich flue gas mixture into the production wells. This method greatly reduces the water cleaning requirements since boiler tubes are no longer used, resulting in greater efficiency and less GHGs. Furthermore, approximately 80% of the CO2 in the flue gas that is injected into the production wells remains underground when the condensed steam and bitumen is pumped back to the surface, lowering GHG emissions. The recovered water can then be recycled with minimal treatment since DCSG can operate with lower water quality requirements. Finally, the DCSG process produces dry tailings, which are easier to manage and dispose of than wet tailings.
11) When can we expect commercialization of DCSG technology?
After roughly a decade in the making; direct contact steam generation technology is three to five years away from commercialization.
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