The Utica Shale is a black, calcareous, organic-rich shale of Middle Ordovician age that underlies significant portions of Ohio, Pennsylvania, West Virginia, New York, Quebec and other parts of eastern North America. In the subsurface, the Utica Shale is located a few thousand feet below the Marcellus Shale, which has become widely known as a source of natural gas.
The Utica Shale is currently receiving a lot of attention because it is yielding large amounts of natural gas, natural gas liquids and crude oil to wells drilled in eastern Ohio and western Pennsylvania. The United States Geological Survey’s mean estimates of undiscovered, technically recoverable unconventional resources indicate that the Utica Shale contains about 38 trillion cubic feet of natural gas, about 940 million barrels of oil, and 208 million barrels of natural gas liquids.
Geologists have long considered the Utica Shale to be an oil and natural gas source rock. Natural gas and oil generated in the Utica Shale have migrated upwards and are produced from reservoirs in overlying rock units. An even greater quantity of oil and natural gas is still trapped in the Utica Shale.
The Utica Shale has not been extensively developed for two reasons: 1) its great depth over much of its geographic extent, and, 2) its limited ability to yield gas and oil to a well because of its low permeability. This is starting to change as horizontal drilling and hydraulic fracturing are used to stimulate production. These methods were not extensively used in the Utica Shale prior to 2010.