A new assessment by the United States Geological Survey found approximately 38 trillion cubic feet of natural gas trapped in the Utica Shale, a rock formation in the eastern United States. The formation also contains an estimated 940 million barrels of oil and 9 million barrels of natural gas liquids.
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The Utica Shale lies beneath another massive natural gas source, the 84 trillion cubic foot Marcellus Shale deposit, in Maryland, New York, Ohio, Pennsylvania, Virginia, and West Virginia.
Despite national security and human rights benefits that a domestic fossil fuel supply provides, research points to dangers from using the gas in these rock formations. The controversial practice of hydraulic fracturing, or fracking, is necessary to release much of the gas from these deposits. Earthquakes have been correlated to fracking in some studies, while others suggest that the fluids used to shatter rocks in the fracking process may contaminate water supplies.
In addition to the risks of fracking, the carbon dioxide produced by the burning of natural gas contributes to climate change, as does the accidental release of the gas itself into the atmosphere. However, the amount of greenhouses gases produced by the combustion of natural gas is lower than that of coal.
Shale gas forms when natural gas remains trapped in the rocks where the gas originally forms, as opposed to conventional gas deposits that form when the gas leaks from the shale and collects in another geologic formation. To release the gas from the shale, high pressure liquids are used to crack the rock and release the gas.
The Utica Shale is a formation in the Appalachian Basin that lies beneath the Marcellus Shale. (USGS)
Schematic cross-section of the subsurface illustrating types of natural gas deposits (US Energy Information Administration, Wikimedia Commons)