Why would you go through all the trouble of doing all those calculations just to waste all that effort on one fatal assumption? That fatal assumption is the same one that has been repeated countless times: you assume it is possibly to linearly extract an entire reserve over time.
I'm not sure why you're so big on natural gas. You do realize that oil, natural gas, and coal are all peaking at the same time? This happens because of price arbitrage. So they all tend to move as one. At least with oil we get a lot more warning and predictability. With natural gas we can lose 10% of production in a year and not even see it coming.
Is There Enough Natural Gas? [View article]
Peak Oil: China vs. USA [View article]