Geoscientist and a fellow at the Post Carbon Institute, J. David Hughes, in a Nature article: “Wells decline rapidly within a few years. Those in the top five US plays typically produced 80–95% less gas after three years. In my view, the industry practice of fitting hyperbolic curves to data on declining productivity, and inferring lifetimes of 40 years or more, is too optimistic. Existing production histories are a few years at best, and thus are insufficient to substantiate such long life-times for wells. Because production declines more steeply than these models typically suggest, the method often overestimates ultimate recoveries and economic performance.” (2013)
Hughes, J. D. (2013). A reality check on the shale revolution. Nature, 494(7437), 307–308.