What is the mathematical basis of your 150 year thing?
And if we have all that nat gas, why doesn’t Brazil? Or Japan? Or Mali?
Geology of millions of years does not care about lines on maps.
In a former life, I worked in the gas industry. In the Utica and Marcellus areas there is decades worth of drilling, and this was data from about a decade ago. We have plenty of gas going forward, our problem is corrupt politicians.
We do not have all the gas, its like other minerals that it is in various places around the world. As to why this is, maybe asking God might provide some answers. May God bless you and those you love.