The Marcellus and Utica Shales contain around 214 tcf of undiscovered, technically recoverable natural gas, according to a new U.S. Geological Survey (USGS) assessment. "This is a significant increase from the previous USGS assessments of both formations. In 2011, the USGS estimated a mean of 84 trillion cubic feet of natural gas in the Marcellus Shale, and in 2012 the USGS estimated about 38 trillion cubic feet of natural gas in the Utica Shale," the agency reports.
You can read more about the USGS's findings here.