Producing crude from Alberta's oil sands poses a number of challenges for the oil and gas industry, including reducing the environmental impact of tailing ponds.
In open-pit mining production, hot water is used to separate bitumen from the sticky sand. This water ends up in a tailings pond, which allows the water to be recycled. Tailings are a mixture of water, clay, sand and residual bitumen.
Fine tailings in particular – which are clays, silts and solids that remain in the floating layer and settle down to mature fine tailings layer after a few years -- pose a challenge for oil sands producers in terms of recovering enhanced bitumen and drying waste material more quickly to speed up the reclamation of tailing ponds. The quality of the water remaining after solids have been removed also poses an issue.
Research efforts to reduce the size of tailing ponds and the time it takes to reclaim land used for these ponds have increased in response to Canada's Energy Resources Conservation Board's (ERCB's) passage in 2009 of Directive 074, handed down legal requirements for oil sands producers to reduce the environmental impact of tailings, which required oil sands producers to reduce the negative environmental impacts of tailings ponds.
These requirements include:
The need to address the environmental impact of tailing ponds will remain as the ERCB forecasts Alberta's annual raw crude bitumen production to total 3.7 million barrels per day for a total of 1.35 billion barrels per year by 2021.
ECRB on June 20 reported that Alberta produced 1.7 million barrels per day of raw crude bitumen from the oil sands in 2011 for a yearly total of 637 million barrels, an 8 percent increase over 2010 oil sands production.
Research Efforts into Oil Sands Tailings Treatments
The treatment of fluid fine tailings – which has been compared to a runny yogurt that behaves like a fluid -- has generated significant research into technology within the oil and gas industry as well as between industry, universities and other industries. The growing volume of this runny yogurt, or 900 million cubic meters, must be contained within settling basins or elsewhere.
Syncrude Canada Ltd. and Suncor Energy Inc. had a long history of working together to address the issue of tailings, with initiatives underway to work together. However, these initiatives tended to be project specific, said Alan Fair, executive director of the Oil Sand Tailings Consortium, which was established in December 2010 to attempt to share tailings research and development among oil and gas producers.
Member companies of the Oil Sand Tailing Consortium include:
"The consortium really builds on the initiatives already underway, as many of the companies were working together already," Fair said. "Now, there is a much broader kind of approach in terms of collaborating in oil sands technology."
The consortium was established with four principles in mind, said Fair. One is that no intellectual property barriers will exist among the member companies to impede them from sharing their research findings with each other.
"For an oil and gas company, that's not the norm," said Fair. "It's not just an agreement; they're legally obligated to share with each other. They can't selectively decide to share some things and not others."
The companies involved must not only share with each other, but with stakeholders as well. This includes posting on the Internet at month's end the results of a study between the oil sands industry and the Alberta government, Fair said.
Collaboration versus cooperation is another principle of the consortium, not only within the industry, but with third party technology developers, vendors, suppliers, universities and government, Fair said. Funding for research is also done on an equitable, not equal basis, with the understanding that some companies will contribute more than others.
Last year, oil sands producers invested over $75 million in research and development (R&D) for technological solutions for tailings, which did not include the operational cost for conducting R&D.
Industrywide research efforts have progressed since the consortium's founding. On March 1, a new organization, Canada's Oil Sands Innovation Alliance (COSIA), was formed to help advance technological research into addressing the challenges of oil sands production. OSTC will be merged under COSIA as one of four environmental priority areas, which including water, greenhouse gases and land reclamation.
"The intent is to set up three additional groups similar to tailings to build off the success we've seen research and development in tailings," said Fair.
The largest tailing pond today at the Mildred Lakes Settling Basin is 10 miles wide and 10 miles long (17 kilometers by 17 kilometers), but tailing ponds from more recent operations are considerably smaller, Fair noted. Over 65 square miles (170 square kilometers) of tailing ponds exist in Alberta.
"We need tailing ponds to recycle water," Fair said. "Having said that, this work will enable tailings ponds to be reduced in size, reclaimed much more quickly. The aim of the Oil Sands Tailings Consortium is not to get rid of them, but to have smaller ponds and faster reclamation."
Directive 74 was already in the works when 1,600 ducks died after being trapped in an oil slick at the surface of a Syncrude tailing pond.. Syncrude was fined for not properly using strategies to prevent birds from landing on these toxic ponds.
"It's a stretch to say that the incident resulted in the directive, but these events influence public opinion and stakeholders," said Fair, noting that more ducks have been killed by wind power.
Directive 74 was "a welcome step in the right direction," said Jennifer Grant, oil sands director for the Pembina Institute.
However, the directive to reduce the proportion of tailings waste didn't address legacy tailings already in existence, but only applies to future growth. Grant said Pembina was disappointed that the ERCB adjusted the timeline for companies to comply with the directive, saying it should be completely enforced.
AlumCAS Sees Market Potential in Tailings Treatment
While research efforts into reducing the footprint of tailings is growing, one company previously focused on wastewater treatment sees opportunity for its product in the tailings market.
AlumCAS, a patented nano-polymer chemical that has been used for wastewater treatment, is now being marketed for use in recovering enhanced bitumen, the thick, stick form of crude oil, and dry the waste material faster, speeding up the reclamation process for tailing ponds.
Tony Robles, who operated the Kirkland Lake water treatment plant, created the AlumCAS system in 2005 to address the issue of water quality at the plant and remove more disinfection by-products. Cost limitations prompted Robles to seek to improve activated silica properties, which were already being used as a flocculent.
The new nanopolymer version can comb out particles that traditional polymers can't handle. AlumCAS, which is made of both alum and silicon, can be mixed on-site with a pumping unit and chemical tank system at a fraction of the cost of plant upgrades, said Stephen Charko, director of business marketing and operations for the company.
The non-toxic product can replace conventional industrial, water or wastewater treatment plant's coagulant or polymer. The oil sands industry can also benefit from AlumCAS' longer half-life which is not prone to gelling, like other market polymers.
AlumCAS can also remove more water than competing products, and can recover enhanced bitumen – the thick, sticky form of crude oil – and dry waste material faster, speeding up the reclaiming process for tailing ponds, said Charko. The company reports that water that comes from the AlumCAS system is one of membrane-quality without the need for an actual membrane.
The oil sands industry has a long history of borrowing technology from other industries to treat tailings. However, it is not usually as simple as taking something off the shelf due to the massive scale of oil sands operations, which are focused on some of the largest mines in the world, said Fair.
Research into tailings technology involves not looking for one right answer, but a suite of technologies, Fair said. "There is no silver bullet because different sites have different conditions."
Developments in Tailings Treatment Technology
Canadian Natural Resources has been adding waste carbon dioxide (CO2) into the tailings streams in order to reduce the size of their tailings ponds, according to the COSIA website.
Adding CO2 causes fine clays, silts and sands to settle more quickly and increases the clarity of the tailings water, which is then re-used in the extraction process, according to the COSIA website.
"Not only does this reduce the amount of fresh water required for extraction, it reduces the overall volume of the tailing ponds," said COSIA.
Mature Final Tailings (MFT) dewatering is another tailings technology being championed by Canadian Natural and other oil sands producers. The process works by treating the soft middle layer of a tailing pond with waste CO2 and a reagent, which binds the solids together and releases the water. The released water is then recovered and recycled.
"These enhanced recycling processes help speed reclamation and decrease the amount of fresh water needed to process bitumen. They also reduce GHG emissions by isolating CO2 in the tailing ponds," said COSIA in a case study on tailings technological innovation.
To manage tailings, Suncor has implemented the TRO process, which involves converting fluid fine tailings more rapidly into a solid landscape suitable for reclamation. MFT is mixed with a polymer flocculent, then deposited in thin layers over sand beaches with shallow slopes. A dry material is created that can be reclaimed in place or moved to another place for final reclamation. The drying process takes weeks instead of years, allowing land to be reclaimed more rapidly.
Syncrude is implementing a multi-pronged approach to manage tailings and comply with government regulations, which includes water capping, composite tails and centrifuge technology. In water capping, fresh water is layered over a deposit of fine tails to form a lake. The composite tails approach involves combining fine tails with gypsum and sand as tailings are deposited, causing them to settle faster.
Syncrude also intends to implement centrifuge technology, in which tailings are put through vessels where a spinning action separates out the water. Released water is then recycled for operations, while the solid product is placed in deposits, then capped and reclaimed.
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