The Marcellus Shale has passed another milestone, this time exceeding 15 Bcf/d of natural gas production in July, according to the Energy Information Administration (EIA).

The agency first released the estimate in July in its Drilling Productivity Report (DPR) (see Shale Daily, July 14), which tracks production in six of the nation’s leading oil and gas fields. It said on Tuesday that the Marcellus, located in Pennsylvania and West Virginia, now accounts for nearly 40% of all U.S. shale gas production, easily making it the nation’s largest gas field. The second-largest gas-producing formation included in the DPR is the Haynesville Shale in Louisiana, Texas and Arkansas, which produced 6.7 Bcf/d in July.

Production growth in the Marcellus has been astonishing, moving from just 2 Bcf/d in 2010 to its current level. In Pennsylvania alone, according to state production data, operators reported producing 3.3 Tcf of unconventional natural gas last year, up from 2.04 Tcf in 2012 (see Shale Daily, Feb. 20), making the state the second largest natural gas producer in the country behind Texas, which produced 6.8 Tcf last year.

Production is only expected to grow in the Marcellus. The rig count there has remained consistent at about 100 over the last 10 months. The EIA said last December that the formation would surpass 13 Bcf/d (see Shale Daily, Dec. 9, 2013) and added on Tuesday that given the steady gains in drilling productivity each new-well rig is expected to support 6 MMcf/d per month.

At that rate, EIA said new wells coming online this month are expected to produce more than 600 MMcf/d of additional production, which the agency said is more than enough to offset the anticipated drop in production from decline rates.

Production in the Marcellus region also surpassed winter demand for natural gas in Pennsylvania and West Virginia years ago, EIA said. Producers working there are now on track to supply enough natural gas to meet the demand in those states plus New York, New Jersey, Delaware, Maryland and Virginia.