Natural gas facility methane emissions: measurements by tracer flux ratio in two US natural gas producing basins

Abstract

Methane (CH 4 ) emission rates from a sample of natural gas facilities across industry sectors were quantified using the dual tracer flux ratio methodology. Measurements were conducted in study areas within the Fayetteville shale play, Arkansas (FV, Sept-Oct 2015, 53 facilities), and the Denver-Julesburg basin, Colorado, (DJ, Nov 2014, 21 facilities). Distributions of methane emission rates at facilities by type are computed and statistically compared with results that cover broader geographic regions in the US (Allen et al., 2013. DJ gathering station emission rates (kg CH 4 hr -1 ) are lower, while FV gathering and production sites are statistically indistinguishable as compared to these multi-basin results. However, FV gathering station throughput-normalized emissions are statistically lower than multi-basin results (0.19% vs. 0.44%). This implies that the FV gathering sector is emitting less per unit of gas throughput than would be expected from the multi-basin distribution alone. The most common emission rate (i.e. mode of the distribution) for facilities in this study is 40 kg CH 4 hr -1 for FV gathering stations, 1.0 kg CH 4 hr -1 for FV production pads, and 11 kg CH 4 hr -1 for DJ gathering stations. The importance of study design is discussed, including the benefits of site access and data sharing with industry and of a scientist dedicated to measurement coordination and site choice under evolving wind conditions.

Comparing facility-level methane emission rate estimates at natural gas gathering and boosting stations

“…They found that tracer may not recover up to 50% of the combustion slip plume when downwind measurements are made at distances of less than 1000 m. Recovery improves with increasing downwind distance. Yacovitch et al (2017) found no evidence of plume rise at gathering stations measured in this study by comparing plume emissions to downwind measurement distance. However, this finding is not absolutely conclusive because downwind measurement distance varied little since it was dictated by the presence of roads (see Figure S14 in Yacovitch et al (2017)).…”

“…Yacovitch et al (2017) found no evidence of plume rise at gathering stations measured in this study by comparing plume emissions to downwind measurement distance. However, this finding is not absolutely conclusive because downwind measurement distance varied little since it was dictated by the presence of roads (see Figure S14 in Yacovitch et al (2017)). Conversely, while combustion slip estimates were developed from a robust dataset, contemporaneous combustion slip measurements were not performed and the possibility of a high bias in modeled combustion slip cannot be eliminated completely.…”

“…During each transect, measurements of tracer gases (N 2 O, C 2 H 2 ) and CH 4 were made with Tunable Infrared Laser Direct Absorption Spectroscopy trace-gas monitors with sub-ppb precision. For a detailed discussion of the methods and results of the tracer-based FLER estimates used in this study, and the associated uncertainty, see Yacovitch et al (2017). All tracer measurements ("tracer") were performed by Aerodyne Research Incorporated.…”

Gathering pipeline methane emissions in Fayetteville shale pipelines and scoping guidelines for future pipeline measurement campaigns

“…Use of natural gas offers potential climate benefits compared to coal or oil (EIA, 2016a), but those benefits depend upon the emissions of methane, the primary component of natural gas and a potent greenhouse gas. This study is part of a larger study designed to compare, and possibly reconcile, estimates of methane emissions developed from aircraft "top-down" measurements (Schwietzke et al, 2017) and inventory-based "bottom up" estimates, including the results presented here and studies of production facilities , gathering compressor stations , and measurements made by downwind techniques (Robertson et al, 2017;Yacovitch et al, 2017) at a variety of facilities.Gathering pipelines refer to the pipelines that connect wells to gathering compressor stations or processing plants, and connect those facilities to transmission pipelines or distribution systems. Inlet pressures of gathering systems range from 30 to 7,720 kPa (Mitchell et al, 2015), but most gathering pipelines operate at the low end of that pressure range.…”

“…Use of natural gas offers potential climate benefits compared to coal or oil (EIA, 2016a), but those benefits depend upon the emissions of methane, the primary component of natural gas and a potent greenhouse gas. This study is part of a larger study designed to compare, and possibly reconcile, estimates of methane emissions developed from aircraft "top-down" measurements (Schwietzke et al, 2017) and inventory-based "bottom up" estimates, including the results presented here and studies of production facilities , gathering compressor stations , and measurements made by downwind techniques (Robertson et al, 2017;Yacovitch et al, 2017) at a variety of facilities.…”