In 1980, the National Petroleum Council estimated that, on average, gas content in the Marcellus Shale
was about 0.5 trillion scf (standard cubic feet).In 1988, this estimate was dramatically revised to 26.5 trillion scf
, and in 2008 the estimate rose again to about 50 trillion scf.Most recently, based on actual production data in the Marcellus Shale gas play, the amount of natural gas estimated to be extractable in the Marcellus increased again to 363 trillion scf