From 2011 to 2012, Pennsylvania's marketed natural gas (which includes natural gas plant liquids) production grew by 72 percent, moving it from the seventh-largest to the third-largest marketed gas-producing state in the U.S., according to the Natural Gas Annual, 2012.

Preliminary data (as well as estimates from the Drilling Productivity Report) indicate that continued Marcellus production may result in Pennsylvania becoming the second-largest natural gas producer in 2013.

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Tight gas development significantly increased production in several regions, including the Marcellus in the Northeast and the Eagle Ford in Texas. Marketed production in the Lower 48 states increased by 5 percent between 2011 and 2012, rising from 23.7 trillion cubic feet (Tcf) to 25.0 Tcf, according to data provided by U.S. Energy Information Administration.

Pennsylvania also saw the largest volume and percentage increases in marketed gas. West Virginia, which is also located in the Marcellus Shale play, joined the top 10 largest U.S. producers for the first time in 2012, producing 146 billion cubic feet (Bcf) of additional marketed gas compared with the 2011 level.

Texas, home to the Eagle Ford Shale play, grew 5 percent year-on-year, and stands as the largest gas-producing state by far.

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