Emission Measurements from Natural Gas Development and Regional Background Characterization of Ambient Air Quality in the Marcellus Shale Region

DeCarlo, Peter; Goetz, J. Douglas; Fortner, Ed; Wormhoudt, Jody; Massoli, Paola; Floerchinger, Cody; Brooks, William; Knighton, Berk; Herndon, Scott; Kolb, Charles; Knipping, Eladio

Production of natural gas in the Marcellus shale formation is increasing rapidly due to the vast quantities of natural gas in the formation. Natural gas is liberated from the Marcellus Shale using horizontal drilling techniques, followed by hydraulic fracturing. Activities associated with preparation of a well pad, drilling of a well pad, fracturing of a well, and transport of materials (e.g. water, drilling equipment) to and from a well site, all have associated air emissions. Steady state gas production at well sites may also have additional contribution to air emissions of methane, volatile organic compounds, NOx, and other species from gas transport infrastructure. A joint study with the Drexel University, Aerodyne Research and the Electric Power Research Institute was conducted in the summer of 2012 to measure both the emissions from various stages of well development and to characterize current levels of air pollutants in the Marcellus Region.

To achieve this, the Aerodyne mobile laboratory was deployed and measured in situ concentrations of a multitude of gas-phase and aerosol chemical components with state of the art instrumentation including quantum cascade laser systems, proton transfer mass spectrometry, tunable diode lasers and a soot particle aerosol mass spectrometer. Tracer-release techniques were used to unambiguously link sources with emissions and to quantify emission rates. To accomplish this inert tracers were released upwind of a facility and the tracer and facility plume was measured downwind. Chemical species measured include methane, ethane, NO, NO2, CO, CO2, SO2, and many volatile organic compounds, and aerosol size and chemical composition. Real-time characterization of the air emissions from hydraulic fracturing and other shale gas operations allow for the estimation of emission factors that can be used in predictive air quality modeling for the region. Measurements were conducted in two regions of Pennsylvania: the NE region that is predominantly dry gas (95% + methane), and the SW region where wet gas is found. A comparison of these two regions and associated impacts will be discussed. Additionally, regional scale measurements of current levels of air pollutants will be presented and will put into context how further development of the gas resource in one of the largest natural gas fields in the world impacts air quality in a region upwind of the highly urbanized east coast corridor.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013