Pennsylvania’s unconventional natural gas producers pulled 390 billion cubic feet of gas from the Marcellus Shale and other resource-rich rock layers in January, according to the first monthly production reports the companies filed with the Department of Environmental Protection.

The numbers released by the state today are the first of what will be regular reports of monthly unconventional gas production after Pennsylvania passed a law last year to increase the frequency of reporting from twice-yearly to monthly to better correspond with the details reported on leaseholders’ royalty checks.

Shale gas production during the month of January averaged 12.6 billion cubic feet per day (Bcf/d), an increase over the daily average during the second half of 2014, the last reporting period, when the state’s unconventional producers averaged 11.5 Bcf/d.

The state does not guarantee the accuracy of its production data, which is self-reported by operators, but the January numbers appear to be in line with figures released by the U.S. Energy Information Administration, which reported that 14.4 Bcf/d was produced in January from the entire Marcellus Shale region, including West Virginia. A DEP spokeswoman said 80 percent of operators reported their January production by the March 31 deadline and the companies that submitted their reports on time represent 99.5 percent of unconventional natural gas wells in Pennsylvania.

Pennsylvania’s top producing counties during the month — Susquehanna, Bradford and Lycoming — were in the northeast, followed by Washington and Greene counties in the southwest.

Nearly one-third of the state’s gas production in January came from the nine counties in southwestern Pennsylvania, which also produced 95 percent of the state’s natural gas liquids, a term that includes ethane, oil and condensate that also are recovered from some shale formations.

The state’s natural gas liquids production for the period totaled 416,000 barrels and Range Resources was responsible for most of it. The Texas-based company, one of the most active in the Marcellus, reported producing 342,000 barrels of condensate in January, all of it from Washington County.

The same five producers who led the state in gas production in 2014 remained the most prolific in January, but the rankings shifted. Cabot Oil & Gas surpassed Chesapeake Energy as the top producer. Chesapeake was second, followed by Southwestern Energy, Range Resources and Downtown-based EQT Corp.

Nine of the 10 most productive wells in January were Cabot Oil & Gas wells in Susquehanna County. The other was a Vantage Energy well in Greene County.

The new state production reporting law requires operators to file future reports within 45 days after the end of the reporting period, which means the February reports will be due to DEP on April 14.