Abstract. The United States has experienced a sharp increase in unconventional natural gas
(UNG) development due to the technological development of hydraulic
fracturing. The objective of this study is to investigate the emissions at
an active Marcellus Shale well pad at the Marcellus Shale Energy and
Environment Laboratory (MSEEL) in Morgantown, West Virginia, USA. Using
an ambient air monitoring laboratory, continuous sampling started in
September 2015 during horizontal drilling and ended in February 2016 when
wells were in production. High-resolution data were collected for the
following air quality contaminants: volatile organic compounds (VOCs), ozone
(O3), methane (CH4), nitrogen oxides (NO and NO2), and carbon
dioxide (CO2), as well as typical meteorological parameters (wind
speed and direction, temperature, relative humidity, and barometric pressure).
Positive matrix factorization (PMF), a multivariate factor analysis tool,
was used to identify possible sources of these pollutants (factor profiles)
and determine the contribution of those sources to the air quality at the
site. The results of the PMF analysis for well pad development phases
indicate that there are three potential factor profiles impacting air
quality at the site: natural gas, regional transport/photochemistry, and engine emissions. There is a significant contribution of
pollutants during the horizontal drilling stage to the natural gas factor. The model outcomes
show that there is an increasing contribution to the engine emission factor over different well
pad drilling periods through production phases. Moreover, model results suggest that
the regional transport/photochemistry factor is more pronounced during horizontal drilling and drillout due
to limited emissions at the site.
Multi-Scale Lithofacies and Chemostratigraphic Analysis of Two Middle Devonian Marcellus Shale Wells in Northern West Virginia, USA