New technology for extracting oil from oil sands could more than double the amount of oil that can be extracted from these abundant deposits. It could also reduce greenhouse-gas emissions from the process by up to 85 percent. The technology was developed by N-Solv, an Alberta-based consortium that recently received $10 million from the Canadian government to develop the technology.
Canada’s oil sands are a huge resource. They contain enough oil to supply the U.S. for decades. But they are made up of a tarry substance called bitumen, which requires large amounts of energy to extract from the ground and prepare for transport to a refinery. This fact has raised concerns about the impact of oil sands on climate change. The concerns have been heightened by plans to build a new pipeline for transporting crude oil from the sands to refineries in the United States.
加 拿大油砂资源丰富。它所能提供的石油足够美国使用数十年。但是其主要成分是一种被称为沥青的焦油状物质。因此从地面开采和把他们运往提炼产都需要消耗大量 的能源。这一现实已经引发了对开采利用油砂矿对气候变化的影响方面的担忧。在公布将建设一条新的石油运输管道把从油砂中提取出的原油运往位于美国的提炼产 之后，这些担忧进一步升级。
Most oil sands production currently involves digging up oily sand deposits near the surface and processing the sludgy material with heat and chemicals to free the oil and reduce its viscosity so it can flow through a pipeline. But 80 percent of oil sands are too deep for this approach. Getting at the deeper oil requires treating the bitumen underground so it can be pumped out through an oil well. The most common technique in new projects involves injecting the bitumen with steam underground. But producing the steam means burning natural gas, which emits carbon dioxide. And the oil that’s pumped out is still too thick to flow through a pipeline, so it has to be partially refined, which emits still more greenhouse gases.
目前，大多数的油砂生产的环节包括从近地面开采油砂矿资源，然后将这些泥糊糊的原材料在高温和化学物质的作用下分离出石油，并降低其粘性，最后就能在油管中运输了。尽管可以采用这种办法，但是80%的 油砂矿都是深埋地底的。要想开采到深层的石油，还要对付地下的地沥青，这样才能通过油井将石油抽上来。在新的工程中最常用的技术，则是往地下的沥青中注入 蒸汽。但是，要生产蒸汽就要燃烧天然气，这还是会产生二氧化碳。此外，要抽出的石油通常都是浓度太高而不能通过油管，所以在这之前还是要部分提炼才行，而 这样做仍然会排放更多的温室气体。
N-Solv’s process requires less energy because it uses a solvent rather than steam to free the oil, says Murray Smith, a member of N-Solv’s board of directors. The solvent, such as propane, is heated to a relatively low temperature (about 50 °C) and injected into a bitumen deposit. The solvent breaks down the bitumen, allowing it to be pumped out along with the propane, which can be reused. The solvent approach requires less energy than heating, pumping, and recycling water for steam. And because the heaviest components of the bitumen remain underground, the oil that results from the solvent process needs to be refined less before it can be transported in a pipeline.
一名N-Solv公司的董事会成员MurraySmith表示，N-Solv公司的处理技术则只要消耗更少的能源就能做到，因为该公司使用的是化学溶剂而不是蒸汽来分离出石油。像丙烷这样的溶剂会加热到相对较低的温度（大约是50摄 氏度）后被注入到沥青层。之后，溶剂会分解沥青，沥青会和丙烷一道会被抽取上来，这样还可以重新利用他们。采用溶剂的方法比加热，抽取，然后再利用生产蒸 汽的水资源这一处理过程要消耗更少的能量。不仅如此，因为沥青中最重的成分都还是埋在地底的，所以利用溶剂提取出的石油不需要深加工，之后就可以由油管运 送出去了。
Because the new process requires less energy, it should also be cheaper. Smith adds that the equipment needed for heating and reusing the propane is less expensive than technology for managing the large volumes of water used in the steam process. With conventional techniques, oil prices have to be above $50 to $60 per barrel—as they have been for several years—for oil sands to be economical. Smith says that with the solvent process, oil sands are still economical even if oil is $30 to $40 per barrel, close to what it was in the 1990s and early 2000s (in inflation-adjusted dollars). N-Solv says the lower costs will make it possible to economically extract more than twice as much oil from the oil sands compared to conventional technologies.
The idea of using solvents to get at oil sands was proposed in the 1970s, but early experiments showed that the process couldn’t produce oil quickly enough. Two things changed that, according to N-Solv. First, horizontal drilling technologies now make it possible to run a solvent injection well along the length of an oil sands deposit, increasing the area in contact with the solvent, thus increasing production. Second, N-Solv determined that even small amounts of methane—a by-product of using a solvent—could contaminate the propane and degrade its performance. So N-Solv introduced purification equipment to separate methane from the propane before it is reused. The separated methane can also be used to heat the propane, further reducing energy costs.
Although N-Solv’s technology could reduce carbon-dioxide emissions from production, most of the emissions associated with oil sands—as with any source of oil—come not from producing the oil, but from burning it in vehicles and furnaces. The technology’s impact on climate change will depend on whether the process leads to increased oil production—if it does, it may actually result in increased net greenhouse-gas emissions, says David Keith, a chemical and petroleum engineering professor at the University of Calgary.
尽管N-Solv公 司的这一技术可以在生产过程中减少二氧化碳的排放量，但是这其中大部分的排放都和油砂有关，其实任何一种石油来源都是如此，排放的二氧化碳不是来自石油生 产环节，而是来自交通工具和锅炉的使用这一环节。这项技术对气候变化的影响，还要取决于它是否导致了石油产出的增加。（加拿大）卡尔加里大学化学和石油工 程学教授DavidKeith表示说，如果石油产出增加了，那么这将会引起温室气体的净排放。
So far, the process has been tested only in a lab. Now N-Solv will begin a pilot project that could produce 500 barrels of oil a day. The $60 million project, which is mostly funded by private sources, will determine whether the process can work on a larger scale.