Mr. Green Car: Exploring where our oil comes from–oil sands
By Allen Penticoff
I don’t know about you, but to me, the two words “oil” and “sand” don’t really sound like they should go together. Really sounds like a mess. And in reality, it is. Especially when it’s washing up on our beaches. But some of it may be powering your vehicle today.
Sometimes called tar sands (which doesn’t sound much better), these “unconventional petroleum deposits” are mixtures of water, clay, sand and very thick oil called “bitumen.” Bitumen is similar to the stuff they spread on our roads to pave them. While found throughout the world, including the United States, Russia and the Middle East, these areas are not large enough to warrant commercial extraction—deposits of oil sands in the largest quantities are in Alberta, Canada, and in Venezuela, where both have oil sand reserves equal to the crude oil reserves of the rest of the world.
In Canada, these oil sands are not too dissimilar from the road in front of your house, they are very thick—like cold molasses. In Venezuela, where it is hot, the mixture is more of a stew that will at least flow, but not much of the Venezuelan oil sand is being extracted at this time because of political issues. It has only been because of the recent increases in crude oil prices and new technology that oil sands have been counted among the world’s oil reserves.
The major problem is this thick oil full of non-oil stuff must be heated and/or diluted a great deal to be filtered and pushed through the pipelines. Also, the oil sands are not flowing freely out of the ground as does crude oil, but is a strip-mining operation, particularly in Canada—meaning heavy equipment to extract it and move it around. Usually, the refining process produces what is considered synthetic oil. Roughly 2 tons of oil sand is needed to produce one barrel of oil. Thus, if the destination product is fuel, the “well to wheels” environmental cost of oil sands may be 10 to 45 percent more greenhouse gases than crude oil. However, oil sand-derived fuels release nearly as much carbon dioxide as burning coal for the energy produced.
Canadian oil sands (and normal crude oil) account for much of the oil now imported to the United States, ahead of crude imported from Saudi Arabia. Canadian and Venezuelan oil sand reserves are estimated to be 3.6 trillion barrels versus 1.75 trillion barrels of conventional crude oil worldwide. Although, the Alberta reserves are only considered 10 percent recoverable with current pricing and technology (173 billion barrels). So, this sandy oil thing is not insignificant. It is expected that by 2015, Alberta’s production could be 3 million barrels per day. That would last 170 years—but the U.S. uses 21 million of the 85 million barrels the world consumes every day, and chips away pretty steadily at these reserves.
The Canadians discovered that removing the sand filters at the pumps increased productivity and allowed more oil sand to flow toward the pump. But the disposal of the oily sand was a problem. At first, they just spread it on local roads to hold down dust—but concerns were raised, and now most goes into underground salt caverns.
That’s after the well may have gone through a “Cyclic Steam Stimulation” (CSS). Three-hundred to 340-degrees Celsius steam is injected into the well for weeks or months. Then, the treated well area is allowed to soak up the heat for several days or weeks before pumping begins. Once the flow tapers off, the well is subjected to this heating process again—repeat as needed until the cost of heating is more than the value of the oil extracted.
However, a related technique, called “Steam Assisted Gravity Drainage” (SAGD), came along in the 1980s and boosted Canada’s production to be second only to Saudi Arabia’s production of oil. In this technique, two horizontal wells are drilled, one about 15 feet above the other. Steam is injected from the upper one, heating the oil sand in the area enough to allow it to be pumped out by the lower well. SAGD has a recovery rate of 60 percent of the oil in place versus CSS’s 20-25 percent recovery rate. Other extraction methods under development include one that sets the oil on fire in the ground to thin it sufficiently to pump.
Most of the heat energy to extract oil sands comes from natural gas. The input/output ratio produces about five to six times the energy in oil as it takes to extract it. A downside is that Alberta’s natural gas supply has peaked and gone flat. To support the oil sand industry, natural gas deliveries to the United States have been cut back (read higher prices). However, it is possible to get energy directly from gasification of the oil sands (but at high capital costs), and even nuclear power is being explored as a low-impact way to power these processes.
I know this is not the most exciting of topics, and the numbers are boring, but take this away from it. The world supply of easy-to-get oil is rapidly depleting, and what is left is becoming harder and more expensive to obtain. It would be far, far easier for you to reduce your oil consumption than it is for the Canadians to dig up frozen tar, thaw, filter and refine it. The more you save, the longer we’ll have oil around to use.
From the Dec. 1-7, 2010 issue