Natural gas production in the Marcellus Region exceeded 15 billion cubic feet per day (Bcf/d) in July, the U.S. Energy Information Administration (EIA) reported.

It's the first time production has reached such levels, the agency said in its latest Drilling Productivity Report.

Marcellus Region production has increased considerably over the past four years, growing from just 2 Bcf/d in 2010.

Over the past 10 months the rig count in the Marcellus Region has remained steady at around 100 rigs, but with continued improvement in drilling productivity EIA expects natural gas production in the Marcellus Region to continue on an upward trend.

Each rig supports more than 6 million cubic feet per day (MMcf/d) in new-well production each month. EIA estimates show that new Marcellus Region wells coming online in August will deliver over 600 MMcf/d of additional production. That is more than enough to offset existing well decline rates, resulting in a net increase in daily production of 247 million cubic feet.

The Marcellus Region is located largely in West Virginia and Pennsylvania. According to the EIA it currently accounts for almost 40% of U.S. shale gas production, making it the largest producing shale gas basin in the United States.

Rising production in the Marcellus Region has outpaced growth in the region's pipeline capacity, which has led to a number of pipeline expansion projects intended to remove bottlenecks.

With expanded pipeline capacity, markets in the Northeast are gaining greater access to Marcellus Region gas and this has contributed to lower natural gas prices.