The U.S. Energy Information Administration (EIA) today reported the U.S. natural gas stocks increased by 30 billion cubic feet last week, with the expected range for a build of between 27 and 31 billion cubic feet anticipated by analysts. Natural gas futures prices were up about 2.2% in advance of the EIA’s report, at around $4.19 per million BTUs, but slipped slightly to around $4.17 immediately following the EIA report.

The EIA reported that U.S. working stocks of natural gas totaled 1.73 trillion cubic feet, about 94 billion cubic feet lower than the five-year average of 1.83 trillion cubic feet. Working gas in storage totaled 2.54 trillion cubic feet for the same period a year ago.

Late season cool weather continued to draw on inventories last week. As natural gas prices rise, two things happen simultaneously. First, coal becomes more attractive again as fuel for power generation. Second, natural gas producers begin to produce more of the fuel. Both work to push natural gas prices down. How this will work itself out will be interesting to watch.

Here’s how stocks of the largest U.S. natural gas producers are reacting to today’s report:

Exxon Mobil Corp. (NYSE: XOM), the country’s largest producer of natural gas, is down about 0.9%, at $88.63 in a 52-week range of $77.13 to $93.67. Exxon also reported first-quarter results this morning.

Chesapeake Energy Corp. (NYSE: CHK) is up about 1.3%, at $19.54 in a 52-week range of $13.32 to $22.97.

EOG Resources Inc. (NYSE: EOG) is up 2.7%, at $123.20 in a 52-week range of $82.48 to $138.20.

The U.S. Natural Gas Fund (NYSEMKT: UNG) is down 0.4%, at $22.67 in a 52-week range of $15.18 to $24.09. The Market Vectors Oil Services ETF (NYSEMKT: OIH) is up about 0.5%, at $42.26 in a 52-week range of $32.54 to $45.12. The first fund tracks spot prices; the second includes major drillers and services companies.