Shale Oil Another Coal Based Synthetic Fuel
By Harold Hough  

            As petroleum prices continue to go up, another energy source is gaining a lot of attention – oil shale.  Oil shale is a fine grained sedimentary rock that also has organic material in it – the same type of organic material found in coal.  Think of oil shale as coal with more rock in it. However, it can burn like coal and has the same sort of potential for producing synthetic fuel.
            Much of the current excitement about shale oil (the product of oil shale) is from the Bakken formation under Montana and North Dakota.  Some have estimated the Bakken oil reserves to be as great as 24 billion barrels of oil.  New rock fracturing technology available starting in 2008 has caused a recent boom in Bakken production. By the end of 2010 oil production rates had reached 458,000 barrels per day outstripping the capacity to ship oil out of the area.
            Despite all the recent excitement, oil shale is not a new energy sources and American miners have looked enviously at its potential in the US every time energy prices have skyrocketed.
            The use of oil shale can be traced back to ancient times.  By the seventeenth century, oil shales were being exploited in several countries.  The Scottish oil shale industry began about 1859, the year that Colonel Drake drilled his pioneer well at Titusville, Pennsylvania.  As many as 20 beds of oil shale were mined at different times.  Mining continued during the 1800s and by 1881 oil shale production had reached one million metric tons per year.  With the exception of the World War II years, between 1 and 4 million metric tons of oil shale were mined yearly in Scotland from 1881 to 1955 when production began to decline, then ceased in 1962.  Canada produced some shale oil from deposits in New Brunswick and Ontario in the mid-1800s.  Currently several countries use some oil shale, with Estonia being the major producer and consumer/
            Oil shale production hasn’t been as successful in the United States.  Settlers found oil shale in Colorado in the 19th Century and even named a creek Stinking Water Creek because of the mixture of oil and water found in it.  In the 20th Century many oil companies were interested in the oil shale in what was called the Green River Formation in Colorado, but only pilot plants were built.  Unocal operated the last large-scale experimental mining and retorting facility in western United States from 1980 until its closure in 1991.  Unocal produced 4.5 million barrels of oil from oil shale averaging 34 gallons of shale oil per ton of rock over the life of the project.
            There are two methods for extracting the oil from the shale, mining or in situ methods.  In the case of mining, the shale is mined, usually from an open pit operation, and the oil shale is transported to a crusher and retorting facility for processing.  After crushing, it is heated in the absence of oxygen to remove gases and the condensable oil.  The oil is then refined.
            Processing the oil underground without mining (in situ) is also an option, although much depends on the porosity of the shale and recovery rates.  The most popular method is called Hydraulic Fracturing - “Fracking.”  Fracking breaks up the rock and then “scrubs the shale with a slurry of frack sand.  Some environmentalists have claimed tha fracking can damage the ground water, but the nature of shale deposits prevents that.  The shale rock is more brittle than most rock layers in the mantel that covers the earth’s surface. Because of this, they are easier to fracture which allows for less pressure to be used in the fracking technique. This reduced pressure causes less of an impact on the surrounding rock layers so they are more likely to stay intact while the shale layer is broken up.  In addition, the average in situ shale formation is thousands of feet underground, while the average drinking well or aquifer is a few hundred feet deep.
            Thanks to conventional mining and in situ methods like fracking, oil shale is promising to become a major coal based synthetic fuel.  Nationwide there are a handful of shale oil fields that could each contain as much as 17 billion barrels of oil, according to a recent study. That's more than the country's largest oil field, Alaska's Prudhoe Bay.  The Texas field, known as the Eagle Ford, is just one of about 20 new onshore oil fields that advocates say could collectively increase the nation’s oil output by 25 percent within a decade.