Measurement of atmospheric pollutants associated with oil and natural gas exploration and production activity in Pennsylvania’s Allegheny National Forest

Abstract

Oil and natural gas exploration and production (E&P) activities generate emissions from diesel engines, compressor stations, condensate tanks, leaks and venting of natural gas, construction of well pads, and well access roads that can negatively impact air quality on both local and regional scales. A mobile, autonomous air quality monitoring laboratory was constructed to collect measurements of ambient concentrations of pollutants associated with oil and natural gas E&P activities. This air-monitoring laboratory was deployed to the Allegheny National Forest (ANF) in northwestern Pennsylvania for a campaign that resulted in the collection of approximately 7 months of data split between three monitoring locations between July 2010 and June 2011. The three monitoring locations were the Kane Experimental Forest (KEF) area in Elk County, which is downwind of the Sackett oilfield; the Bradford Ranger Station (BRS) in McKean County, which is downwind of a large area of historic oil and gas productivity; and the U.S. Forest Service Hearts Content campground (HC) in Warren County, which is in an area relatively unimpacted by oil and gas development and which therefore yielded background pollutant concentrations in the ANF. Concentrations of criteria pollutants ozone and NO₂ did not vary significantly from site to site; averages were below National Ambient Air Quality Standards. Concentrations of volatile organic compounds (VOCs) associated with oil and natural gas (ethane, propane, butane, pentane) were highly correlated. Applying the conditional probability function (CPF) to the ethane data yielded most probable directions of the sources that were coincident with known location of existing wells and activity. Differences between the two impacted and one background site were difficult to discern, suggesting the that the monitoring laboratory was a great enough distance downwind of active areas to allow for sufficient dispersion with background air such that the localized plumes were not detected.

Implications

Monitoring of pollutants associated with oil and natural gas exploration and production activity at three sites within the Allegheny National Forest (ANF) showed only slight site-to-site differences even with one site far removed from these activities. However, the impact was evident not in detection of localized plumes but in regional elevated ethane concentrations, as ethane can be considered a tracer species for oil and natural gas activity. The data presented serve as baseline conditions for evaluation of impacts from future development of Marcellus or Utica shale gas reserves.

Acknowledgment

The authors acknowledge the assistance of Ralph Perron, Jim McCloskey, Ernie Wiltsie, and Susan Stout of the U.S. Forest Service Allegheny National Forest and the Northern Research Station in establishing the monitoring locations and providing guidance, and James Sams of the National Energy Technology Laboratory for preparing a figure used in the paper.

Additional information

Notes on contributors

Natalie J. Pekney

Natalie J. Pekney and Garret Veloski are researchers on the Engineered Natural Systems Division Monitoring Team at the U.S. Department of Energy’s National Energy Technology Laboratory (NETL), Pittsburgh, PA.

Matthew Reeder

Matthew Reeder is an Oak Ridge Institute for Science and Eduation post-graduate researcher at NETL, Pittsburgh, PA.

Joseph Tamilia

Joseph Tamilia is a retired engineering technician, formerly with URS Corporation, Pittsburgh, Pennsylvania.

Erik Rupp

Erik Rupp is a researcher in the Department of Energy Resources Engineering, Stanford University, Stanford, CA.

Alan Wetzel

Alan Wetzel is a U.S. Forest Service employee at the Allegheny National Forest Bradford District, Bradford, PA.