Natural gas distributed throughout the Marcellus black shale in northern Appalachia could conservatively boost proven U.S. reserves by trillions of cubic feet if gas production companies employ horizontal drilling techniques, according to a Penn State and State University of New York, Fredonia, team. "The value of this science could increment the net worth of U.S. energy resources by a trillion dollars, plus or minus billions," says Terry Engelder, professor of geosciences, at Penn State. The Marcellus shale runs from the southern tier of New York, through the western portion of Pennsylvania into the eastern half of Ohio and through West...