Photo Essay: Dirty Oil
As oil has become scarcer and more expensive, oil companies have begun seriously pursuing a politically charged method of oil extraction in Canada.
The world’s second-largest oil reserve lies under Alberta in the form of oil sand, which must be processed extensively to yield bitumen, a hydrocarbon mixture related to asphalt that can be turned into crude oil. It is estimated that 174 billion barrels of oil of varying quality could be recovered from the sands. Development is speeding ahead: so far, 34 billion Canadian dollars have been spent developing the oil sands, and another 45 billion in development projects will be completed by 2010 by companies including Petro-Canada, Syncrude, and Suncor.
Oil companies use large machinery and pipelines to transport the sand and rely on welling technologies to extend their reach to the bitumen buried far below the surface. With production at about one million barrels of oil per day in 2005 and expected to double by 2010, environmental groups worry that oil-sands development is speeding ahead too quickly. The following photos illustrate the process–and impact–of getting oil from sand.
1. A grain of oil sand consists of a mostly quartz particle enveloped in a film of water, which is surrounded by bitumen, a thick, heavy oil. It takes roughly two metric tons of this sticky sand to produce one barrel of crude oil. [Click here to view image.]
2. Where the oil sands lie close to the surface, mostly near the town of Fort McMurray in Alberta, they can be mined. In the effort to get at these sands, areas have been drained of wetlands and stripped of boreal forests, which play an important role in climate regulation and carbon storage. Their destruction contributes to the greenhouse effect. [Click here to view image.]
3. About 80 percent of Alberta’s oil sand is too far below the surface to dig up. The most common method for getting the bitumen out is through two parallel horizontal wells lined with perforated pipe. Heat from high-temperature steam injected down one of the wells softens surrounding bitumen–which in oil sand form normally flows about as easily as Crisco–causing it to separate from the sand and flow down into the second well, from which it is pumped to the surface. [Click here to view image.]
4. Equipment used by oil-sand miners includes tractors with top-mounted radiators and cooling fans to protect their engines from oil particles and sludge, thousand-metric-ton shovels, and the Caterpillar 797. This colossal dump truck weighs more than 500 metric tons when empty. When its tires wear out after about a year, they are reused as cattle feeders.
Producing crude oil from the Alberta sands is an energy-intensive process. Giant digging and transportation machines use commensurately large amounts of fuel. Refining and welling technologies consume roughly 30* cubic meters of natural gas per barrel of recovered oil. Environmental watchdogs estimate that, as a result, producing a barrel of oil from the Alberta sands releases two to three times the volume of greenhouse gases that traditional oil production would. By 2015, production from the oil sands is projected to release 94 megatons of greenhouse gases.
Oil sand retrieved from surface mining is crushed and then moved to a processing plant via “hydrotransport.” As the sand, mixed with water, tumbles through transport pipes, the clumps of bitumen, sand, and water begin to loosen. [Click here to view image.]
*In the version of this article that appeared in the Dec. 2005/Jan. 2006 issue of Technology Review magazine this figure was mistakenly cited as 300.
5. The sand-and-water slurry is dumped into tanks with hot water, where it separates into three layers: sand, bitumen froth (impure bitumen), and a middle layer that is further treated to extract bitumen. Bitumen froth is also treated to remove impurities. [Click here to view image.]
6. Oil companies create ponds in which to dump millions of cubic meters of the sandy, toxic by-product of oil-sand processing. These “tailings ponds” are characterized by salt and acids. Here, a worker installs a scarecrow to keep birds away. [Click here to view image.]
7. Bitumen is a viscous mixture of long hydrocarbon chains–strings of as many as thousands of carbon atoms bonded to hydrogen atoms. These molecules must be “upgraded” to shorter molecules before they can be refined into petroleum products.
Purified bitumen is heated to break its long hydrocarbon chains into lighter molecules, such as naphtha, that can be refined. This process is called coking and takes place in large towers. The high-carbon by-product of the process, called coke, in turn fuels the coking furnaces. Distillation and a hydrogenation process are the final steps. [Click here to view image.]
8. The extensive processing of oil sand generates “sweet” crude oil, so called because of its low levels of sulfur and other impurities. Crude oil can be refined into gasoline of different grades and chemicals for making plastics. [Click here to view image.]
Photo 1: Lara Solt/Dallas Morning News/Corbis; photo 2: Greg Smith/Corbis; inset: courtesy of Suncor Energy, Inc.; photo 3: Courtesy of Petro-Canada; photo 4: Courtesy of Suncor Energy, Inc.; photo 5: Hans-Juergen Burkard/Bilderberg; inset: courtesy of Suncrude Canada Ltd.; photo 6: Hans-Juergen Burkard/Bilderberg; photo 7: Courtesy of Syncrude Canada Ltd.; photo 8: Courtesy of Syncrude Canada Ltd.
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