This report (click here) shows the dramatic decline rates of 4 gas fields –

Barnett, Fayetteville, Woodford and Haynesville.  Nearly 2,000 horizontal shale gas wells were included in this study, so these rates are not statistical flukes.

FROM THE REPORT:
To examine the history of any era or series of events, one must have a statistically significant database. One or two points do not define a trend. Accordingly, the portion of a shale gas production decline rate study detailed in this article [has examined] wells in the Barnett, Fayetteville, Woodford and Haynesville plays. The following figures from the report clearly show the rapid downward trend in production.