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| Titel |
Investigation of natural gas plume dispersion using mobile observations and large eddy simulations |
| VerfasserIn |
Dana R. Caulton, Qi Li, Levi Golston, Da Pan, Elie Bou-Zeid, Jeff Fitts, Haley Lane, Jessica Lu, Mark A. Zondlo |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250130885
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| Publikation (Nr.) |
 EGU/EGU2016-11209.pdf |
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| Zusammenfassung |
| Recent work suggests the distribution of methane emissions from fracking operations is
skewed with a small percentage of emitters contributing a large proportion of the total
emissions. These sites are known as ‘super-emitters.’ The Marcellus shale, the most
productive natural gas shale field in the United States, has received less intense focus for
well-level emissions and is here used as a test site for targeted analysis between current
standard trace-gas advection practices and possible improvements via advanced modeling
techniques. The Marcellus shale is topographically complex, making traditional techniques
difficult to implement and evaluate.
For many ground based mobile studies, the inverse Gaussian plume method (IGM) is used
to produce emission rates. This method is best applied to well-mixed plumes from strong
point sources and may not currently be well-suited for use with disperse weak sources,
short-time frame measurements or data collected in complex terrain. To assess the quality of
IGM results and to improve source-strength estimations, a robust study that combines
observational data with a hierarchy of models of increasing complexity will be presented. The
field test sites were sampled with multiple passes using a mobile lab as well as a
stationary tower. This mobile lab includes a Garmin GPS unit, Vaisala weather station
(WTX520), LICOR 7700 CH4 open path sensor and LICOR 7500 CO2/H2O open
path sensor. The sampling tower was constructed consisting of a Metek uSonic-3
Class A sonic anemometer, and an additional LICOR 7700 and 7500. Data were
recorded for at least one hour at these sites. The modeling will focus on large eddy
simulations (LES) of the wind and CH4 concentration fields for these test sites. The
LES model used 2 m horizontal and 1 m vertical resolution and was integrated in
time for 45 min for various test sites under stable, neutral and unstable conditions.
It is here considered as the reference to which various IGM approaches can be
compared.
Preliminary results show large variability in this region which, under the observed
meteorological conditions, is determined to be a factor of 2 for IGM results. While this level
of uncertainty appears adequate to identify super-emitters under most circumstances, there is
large uncertainty on individual measurements. LES can provide insights into the expected
variability and its sources and into sampling patterns that will allow more robust error
estimates. |
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