I just put up a post on Natural Gas using Webhubbletelescope's Shock model with data from Jean Laherrere and Steve Mohr.
http://peakoilbarrel.com/world-natural-gas-shock-model/
Summary
Natural Gas is at an earlier stage of development than crude oil and there is greater uncertainty about the eventual ultimately recoverable resources (URR). Estimates range from 13,000 TCF (Jean Laherrere) to 28,000 TCF (combined EIA and USGS estimates for conventional, shale, and tight gas plus Steve Mohr’s case 3 estimate for coal bed methane.)
I decided to match Laherrere’s estimate (13,000 TCF) for my low case based on Hubbert Linearization for conventional natural gas and conservative estimates of World shale gas, tight gas, and coal bed methane URR (2000 TCF total). For the high case I decided to use Mohr’s case 2 estimate for coal bed methane along with USGS and EIA estimates for other natural gas rescources, URR =26,000 TCF. My best guess is just the average of the low and high case, the scenarios presented peak in 2018, 2039, and 2049.