Variation in Methane Emission Rates from Well Pads in Four Oil and Gas Basins with Contrasting Production Volumes and Compositions

Abstract

Atmospheric methane emissions from active natural gas production sites in normal operation were quantified using an inverse Gaussian method (EPA's OTM 33a) in four major U.S. basins/plays: Upper Green River (UGR, Wyoming), Denver-Julesburg (DJ, Colorado), Uintah (Utah), and Fayetteville (FV, Arkansas). In DJ, Uintah, and FV, 72-83% of total measured emissions were from 20% of the well pads, while in UGR the highest 20% of emitting well pads only contributed 54% of total emissions. The total mass of methane emitted as a percent of gross methane produced, termed throughput-normalized methane average (TNMA) and determined by bootstrapping measurements from each basin, varied widely between basins and was (95% CI): 0.09% (0.05-0.15%) in FV, 0.18% (0.12-0.29%) in UGR, 2.1% (1.1-3.9%) in DJ, and 2.8% (1.0-8.6%) in Uintah. Overall, wet-gas basins (UGR, DJ, Uintah) had higher TNMA emissions than the dry-gas FV at all ranges of production per well pad. Among wet basins, TNMA emissions had a strong negative correlation with average gas production per well pad, suggesting that consolidation of operations onto single pads may reduce normalized emissions (average number of wells per pad is 5.3 in UGR versus 1.3 in Uintah and 2.8 in DJ).

Methane emissions from oil and gas production sites in Alberta, Canada

“…In line with previous studies in the US (Brantley et al, 2014;Rella et al, 2015;Yacovitch et al, 2015;Omara et al, 2016;Robertson et al, 2017), our measurements are characterized by skewed distributions: for the systematic sample 20% (5 of 25) of the measurements account for 68% (33 of 49 kg CH 4 h -1 ) of total measured emissions, while for the high-emitter biased sample 29% (10 of 35) of the measurements account for 85% of total measured emissions (240 of 280 kg CH 4 h -1 ).…”

“…The proportional loss rate (CH 4 emissions normalized by CH 4 production) is another commonly used metric to characterize emissions from natural gas production sites Omara et al, 2016;Robertson et al, 2017). This metric can simplify the intercomparison among production regions with similar characteristics (e.g., similar gas/oil production volumes).…”

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

“…Additional results from these coordinated campaigns are published separately (Robertson et al, 2017;Schwietzke et al, 2017) including synthesis and reconciliation of diverse methodologies for the FV production sector (Bell et al, 2017) and the FV gathering sector (Vaughn et al, 2017).…”

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.…”