Engineering & Mining Journal

AUG 2013

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OIL SANDS infilling the pond with 30 million mt of reclaimed tailings sand, with drainage systems then installed to manage water runoff. The final stage involved placing 1.2 Mm3 of topsoil over the surface, to a depth of 500 mm. The long-term aim, the company said, is to create an area of productive forest and wetland, with 630,000 shrubs and trees planted during 2010. It will be carrying out a 20-year soil, water and vegetation monitoring program. Meanwhile, at Syncrude's Aurora operation, a new tailings-management plant is scheduled to come on stream in September, with the aim of reducing the volume of fine tailings by converting large amounts into reclamation-ready material. The Aurora Tailings Management (ATM) project includes the construction of a new C$800-million Composite Tailings (CT) plant, designed to produce a combined material consisting of fine tailings, coarse sand and gypsum, which effectively flocculates the fines into larger particles that settle faster. CT is then capped with sand and soil for final revegetation. According to Syncrude, the CT process has proved to be one of its most successful tailings-management technologies, and has been used since 2000 to fill the company's former East mine at Mildred Lake in preparation for soil capping in as little as one-totwo years. It expects the ATM project to convert nearly two-thirds of Aurora's total volume of fine tailings—some 150 Mm3— into reclamation-ready material over the life of the mine. In February, Syncrude began the industry's first commercial demonstration of tailings water-capping technology, with the ending of tailings deposition into the Base mine lake. After some 25 years of studies and the formation of 11 test ponds, the company is confident that fine tailings can be stabilized by covering them with a water layer, its research having indicated that, over time, a water-capped lake will evolve into a healthy aquatic environment. The water depth in the Base mine lake has been increased from 3.5 m to 5 m with spring run-off, sourced from a nearby reservoir, helping to bring in nutrients and seeds to kick-start the revegetation process. The Carbon Dioxide Debate One of the principal accusations leveled at the oil sands industry is that the production of oil by this method produces more carbon dioxide per barrel than conventional production techniques. In 2012, IHS CERA 32 E&MJ; • AUGUST 2013 issued an update to its 2010 report Oil Sands, Greenhouse Gases, and U.S. Oil Supply: Getting the Numbers Right, which had demonstrated that oil sands oil is by no means "top-of-the-pile" when it comes to production GHG emissions. While Saudi light oils do result in lower production emissions, it said, some U.S. and Nigerian heavy oils, for example, generate more CO2 during the process for getting the oil from the wellhead to the petrol pump. One key point that IHS made is that the bulk of emissions from using oil as a transport fuel—comprising around 80% of the total—are the same, no matter what the source of the original crude. It is only at the production stage, from source to refinery, that Canada's oil sands emit more CO2 than conventional wells, reflecting the higher energy requirements for mining or in-situ bitumen recovery. Without going into specific detail, of which the report contains plenty, IHS estimated that the average sands-derived oil refined in the U.S. in 2011 generated 9%–12% more CO2 per barrel of refined product than the overall average for the U.S., when taken on a "well-to-wheels" basis. However, that average masks a considerable range, with in-situ SAGD synthetic crude production emitting markedly more CO2 per barrel of product than say, dilbit from a surface mining operation. This is, of course, one of the principal weapons in the environmental lobby's armory in the debate over future energy security and carbon emissions in the U.S., and in relation to Keystone XL. Critics suggest that it is unsustainable to use Canadian oil sands bitumen and synthetic crude because of their higher well-to-wheels production emissions. Supporters point out that oil sands oil is a secure supply, and reduces the need for the U.S. to import heavy crudes from countries such as Venezuela. In the meantime, the producers such as Syncrude and Suncor are themselves looking at ways of reducing their own production-energy requirements. As an example, Syncrude cut its energy usage per barrel by 39% between 1982 and 2009, and targeted a further 11% reduction by this year. In its 2011 report, Oil Sands Technology: Past, Present and Future, IHS noted that from 1990 to 2010 the intensity of GHG emissions per barrel of output for mining and upgrading operations fell by 37% on a well-to-wheels basis, while those for SAGD operations fell by 8% in the first 10 years of commercial usage. This trend is expect- ed to continue, although increased production will result in an overall rise in GHG emissions, perhaps doubling to around 10% of Canada's total emissions by 2030. Water consumption has also fallen on a per-barrel basis, IHS said, with more brackish water being used and less make-up water being drawn from the Athabasca River for bitumen recovery and upgrader operations. The Old and the New Suncor's mining operations produced 103.3 Mbbl of SCO in 2012, sourcing upgrader feed from its Millennium mine. Output from Syncrude's Mildred Lake mine and upgrader totaled 106.4 Mbbl of SCO, while its Aurora North mine produced 67.3 Mbbl of bitumen. The Shell-led Albian Sands operations, Muskeg River and Jackpine, produced 46.6 and 35.5 Mbbl of bitumen, respectively, with their output being pipelined to the project's Scotford upgrader near Edmonton. This converted the bitumen feed to 77.8 Mbbl of SCO. Canadian Natural Resources' Horizon mine contributed a further 31.8 Mbbl to the province's total, which came to 330 Mbbl of SCO plus 263 Mbbl of bitumen derived from in-situ operations. Horizon consists of a surface mine, bitumen-recovery plant and upgrader, and currently has the nameplate capacity to produce 110,000 bb/d of SCO. Canadian Natural is focusing on phased expansions that are manageable under financial and labor-availability constraints, with the aim of increasing output to 250,000 bbl/d initially, then potentially double this. In May, the company reported that its expansion program was running some 10% under budget, with work on the 150,000-bbl/d-capacity increase about 20% complete. "The availability of construction contractors and related services has been better than expected," said company President Steve Laut. "As a result, we continue to see bidders sharpen their pencils." Located about 70 km northwest of the industry's hub, Fort McMurray, Horizon has started a new trend in the oil sands industry by offering camp housing for fly-in/flyout workers from Edmonton, Calgary, and other regional centers, as well as permanent accommodations in Fort McMurray itself. Latest out of the starting blocks has been Kearl, a joint venture between Imperial Oil and ExxonMobil Canada. Kearl, 75 km northeast of Fort McMurray, differs from the other mining projects in that it will only produce dilbit for the refinwww.e-mj.com

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