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Measurement of Air Quality Impacts During Hydraulic Fracturing on a Marcellus Shale Well Pad in Greene County, Pennsylvania

Pekney, Natalie; Veloski, Garret; Reeder, Matthew; Tamilia, Joseph; Diehl, Rodney; Hammack, Richard W.

NETL's mobile air monitoring laboratory was deployed to a Marcellus Shale well pad in Greene County, Pennsylvania to collect measurements of pollutant concentrations before and during hydraulic fracturing. A comparison of background ambient concentrations of pollutants associated with natural gas operations with concentrations of the pollutants measured during the various phases of hydrofracturing operations enabled an evaluation of the impact the activities had on local air quality. Instruments in the laboratory measured the ambient concentrations of methane, carbon dioxide, carbon isotopes in methane and carbon dioxide, volatile organic compounds, nitrogen oxides, ozone, particulate matter, sulfur dioxide, ammonia, organic and elemental carbon aerosols, as well as several meteorological parameters. Monitoring commenced on March 8, 2012 and ended on June 19, 2012. During this time, there were periods of no well pad activity that could be compared to periods of hydraulic fracturing activities. Three of six horizontal wells were hydraulically fractured from April 24 to May 7, and the other three wells where hydraulically fractured from June 4-11. During periods of low or no activity on the well pad, measured pollutants registered typical atmospheric background values with few exceptions. However, significant increases in concentrations of methane, NOx, PM10, and several VOCs were observed during the two hydraulic fracturing operations. Methane concentration and isotope data were used to distinguish between biogenic and thermogenic methane. This technique provides a fingerprint of fugitive methane emissions from the wells. During the fracturing of the first three wells, peaks in methane concentration correlated with changes in the methane isotopic signature to reflect influence of thermogenic methane. A similar pattern was observed during the fracturing of the second three wells, although the most significant evidence of thermogenic methane occurred afterward during flowback. Preliminary results from this project suggest that although measurements did not at any time exceed applicable exposure limits or air quality standards, there were discernible differences in measurements collected during the various phases of operation at the well pad. A complete evaluation of all the collected data will be presented, with estimates of well pad emissions distinguished from background conditions.


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