ONE of the bleakest scenes of man-made destruction is the strip mining of oil sands in the forests of Alberta, Canada. The sand is permeated with natural bitumen, a type of petroleum with the consistency of peanut butter. Once dug from the surface, the sand is hauled to an extraction plant where it is mixed with lots of hot water and chemicals to liberate the oil and make it flow into pipelines or be taken by tankers to refineries. Not all of the water can be recycled and what remains is a goopy toxic waste contained in some 170 square kilometres of man-made ponds.
It is hardly surprising that environmental campaigners want to restrict or shut down the growing “tar sands” industry, as it is also called (as tar is a man-made substance, the industry uses the term oil sands). But the commercial stakes are high. Only Saudi Arabia and Venezuela have greater proven oil reserves than Canada, but 97% of Canada’s 174 billion barrels are in oil sands, mostly in Alberta.
In the past decade high oil prices have made the oil sands profitable to exploit. But the oil industry, whose reputation for protecting the environment is already poor, has come under pressure to find more efficient and cleaner ways to extract the oil. The results of that innovation are now starting to be deployed.
Many operators now extract the bitumen without strip mining. “In-situ” production, as it is called, involves injecting high-pressure steam, heated to more than 300°C, into deep boreholes. The steam, emerging from millions of slits in a steel borehole liner, liquefies the bitumen and allows it to be pumped out.
Using steam extraction means that nine-tenths of the land above a reservoir can be left intact. There is no need for waste ponds because the sand is left underground and most of the water recovered from the bitumen can be cleaned with distillation for reuse. Steam can also produce bitumen from a reservoir half-a-kilometre underground, whereas strip mining is only economical for deposits less than 70 metres or so from the surface.
The proportion of bitumen produced with steam now stands at 53% and will continue to grow, says the Alberta Energy Regulator (AER), a government agency. One of the newer methods, steam-assisted gravity drainage (SAGD), has proved particularly effective, says Ken Schuldhaus of the AER. SAGD involves drilling two horizontal wells through an oil-sands reservoir, one about five metres below the other. Steam is then released from the top well and over a few weeks can melt bitumen as far as 50 metres above and to the sides of the bore. The bitumen then percolates down and into the lower well, from which it is pumped to the surface.
All that gas
Generating steam, though, requires burning a lot of natural gas, and this creates emissions. Another innovation promises to reduce energy and emissions. In a trial last year, Suncor, an Alberta firm, found that adding oil-based solvents to steam increases recovery while reducing the amount of water that has to be heated by 15%. Suncor will begin commercial production within a year using solvents that include butane, propane and a proprietary substance that weakens the surface tension between liquids and solids. Another Alberta firm, Laricina Energy, reckons it can cut the amount of water that needs to be heated by 25% or more. Such reductions promise to reduce break-even costs.
Costs and emissions could be reduced even further in a $100m trial begun this year near Cold Lake. Imperial Oil, based in Calgary, has replaced steam altogether by injecting solvents under high pressure but at much lower temperatures. Pius Rolheiser, the firm’s head of government affairs, says success hinges on being able to separate and reuse the solvents pumped to the surface along with the bitumen.
More radical processes are on the way. This year Suncor began building facilities in Alberta to test melting bitumen with microwaves. It will insert a microwave-transmitting antenna into a horizontal borehole with the circumference of an arm but the length of a football pitch. The idea, says Don Clague, Suncor’s senior vice-president of in-situ technologies, is to melt bitumen without wasting energy heating sand and rock—just as domestic microwave ovens heat moist food but not its glass or ceramic container. Laboratory tests suggest this could slash energy costs by 80%.
Other technologies may come into play. Germany’s Siemens is developing a system that floods a thick copper cable with an electrical current to create an alternating magnetic field to melt bitumen. Les Little of Alberta Innovates, a government body that has worked with Siemens on the project, hopes it will be tested in the province within a few years. The electricity required to run such a process might come from small nuclear reactors, says Jerry Hopwood of Candu Energy, a nuclear-technology company based near Toronto. It has studied designs for reactors that would be small enough to be trucked from Edmonton to the big oil-sands operations around Fort McMurray, Alberta.
Use of the new technologies is spreading quickly, says Suncor’s Mr Clague, thanks in part to a body called the Canadian Oil Sands Innovation Alliance, in which member firms share information about their developments. The new techniques might not allay the fears of some conservationists, but as oil companies are typically obliged to restore the landscape once extraction is complete, making less mess in the first place should help ensure they do a better job of cleaning up.