They must be. Or maybe the Chinese drilled through the core of the earth and are siphoning it off from the bottom (their top).
Only last April (of 2011) our Energy Information Agency (EIA) was saying we had 827 trillion cubic feet (cf) of natural gas. Now we have the U.S. Geological Survey (USGS) saying we have 84 trillion cf of technically recoverable oil and gas resources. Technically in this case refers to the fact that we can get it out with today’s technology, but that it might be too expensive to do so.
As we currently consume 23 trillion cf of natural gas each year. So with the original 827 trillion cf estimate we had 36 years of supply. Now with 84 trillion cf being the new number we have 3.6 years of supply (22 years from all sources) from the Marcus Shale.
Any of these numbers are far less than the 100 years of supply that has been hyped.
Why the big swing. The EIA took the results from a few wells (presumably the easiest to tap) and extrapolated these numbers to the entire area. The USGS, who are the rock people, actually looked at the geology of the entire area. Since the EIA is going to use the USGS numbers from this point, we know which ones are more reliable.
Note that Decline of Empire discusses this all in more depth. But I found the source material (Bloomberg) to be very confusing, which tended to make that piece a bit confusing as well. Here I am trying to break out only the most basic numbers in question, for more details I would encourage you to go to the original Declineof Empire post.