The number of rigs operating in the Marcellus gas play declined, though production there increased 72 percent since last year, the U.S. government reports.

The U.S. Energy Department reports that the number of oil and natural gas rigs active in the Utica shale play in the northeastern United States has doubled.

The U.S. Energy Department's Energy Information Agency reports that year-on-year figures for October 2012 indicate rig activity in the play, spread out of the Appalachian Basin, has doubled.

"For the Appalachian Basin as a whole, the result has thus been a shift away from drilling for Marcellus shale gas in Pennsylvania and toward drilling for Utica shale oil in Ohio," the agency stated.

The EIA said despite the rig count decline in the Marcellus play, natural gas production increased 72 percent in October compared to the same time last year. The 6.8 billion cubic feet per day produced there represented about 26 percent of U.S. shale natural gas production.

By contrast, Utica shale gas production in Ohio, where the bulk of the reserve is situated, was on average 700,000 cubic feet per day, the Ohio government stated.

The United States is a world leader in shale natural gas reserves. Exploiting the reserves is controversial because of potential environmental harm.