The Energy Information Administration (EIA) posted an article recently entitled, "Projected natural gas prices depend on shale gas resource economics." From the article: "Considerable uncertainty exists regarding the size of the economically recoverable U.S. shale gas resource base and the cost of producing those resources. *** This uncertainty exists primarily because shale gas wells exhibit a wide variation in their initial production rate, rate of decline, and estimated ultimate recovery per well (or EUR, which is the expected cumulative production over the life of a well)."
The related graph: