Total dry natural gas proved reserves reached a new record of 354 trillion cubic feet (Tcf) in 2013, according to EIA’s recently published report, U.S. Crude Oil and Natural Gas Proved Reserves, 2013.
Check it out:

Proved reserves are the volumes of oil and natural gas that can be recovered with reasonable certainty under existing economic and operating conditions. Reserves increased 10%, or about 31 Tcf, from the previous year. Increases were the result of extensions to new fields and new discoveries, as well as higher prices, which make gas recovery more economical. In the Marcellus Shale area, the reserves increases were largely the result of new discoveries and continued development. In the Barnett Shale, which has been in development much longer, increases in reserves were mainly attributable to price increases.