PHILADELPHIA -- "The U.S. Geological Survey (USGS) on Tuesday dramatically increased its estimate of the natural gas contained in the Marcellus Shale, the deep deposit that has triggered a drilling frenzy in Pennsylvania. The USGS now estimates that the shale contains about 84 trillion cubic feet of undiscovered, technically recoverable natural gas and 3.4 billion barrels of undiscovered, technically recoverable natural gas liquids.





The agency's latest numbers are 42 times greater than its 2002 assessment, which said the shale contained about two trillion cubic feet of gas (see chart above). The Marcellus lies under Pennsylvania and seven other Appalachian states. The USGS attributed the increase to new geologic information from shale-drilling operations, which have ramped up in recent years because of new developments in extraction technology.





The Marcellus Shale Coalition, the industry trade group, did not miss the opportunity to tweak skeptics who have expressed doubts about the longevity of the reserves.





"While some critics continue to question the viability of responsible domestic shale gas development, it is abundantly clear - as laid out by this new data - that the Marcellus Shale will continue to lead the way in meeting Americans' energy needs for years to come," Kathryn Z. Klaber, the coalition's president, said in a statement."