Comparison of methane emission estimates from multiple measurement techniques at natural gas production pads
Comparison of methane emission estimates from multiple measurement techniques at natural gas production pads
复制标题
DOI：
10.1525/elementa.266
复制
发表时间：
2017-12-27
影响因子：
3.9
通讯作者：
Soltis, Jeffrey
中科院分区：
文献类型：
--
作者：
Bell, Clay S.;Vaughn, Timothy L.;Soltis, Jeffrey
本研究介绍了一项活动的结果，该活动使用现场测量（261个设施）和两种顺风方法-双示踪剂通量比方法（示踪剂设施估计- TFE，17个设施）和EPA其他测试方法33 a（OTM 33 A设施估计- OFE，50个设施）估计费耶特维尔页岩气区268个天然气生产设施的甲烷排放量。通过结合直接测量和模拟未测量的排放源，使用操作员活动数据和文献中的排放数据，开发了每个设施的研究现场估计（SOE）。SOE的范围为0-403 kg/h，液体卸载的模拟甲烷排放量占SOE估计的总排放量的88%，其中76%（95%CI [51%-92%]）由两个设施的液体卸载贡献。TFE和SOE显示16家机构中有15家（94%）机构的个体估计值之间存在95% CI重叠，其中测量值配对，而OFE和SOE显示43家机构中有28家（65%）机构的个体估计值之间存在95% CI重叠。然而，对成对估计值集进行的方差加权最小二乘（VWLS）回归表明方法之间存在统计学显著差异。SOE代表设施的排放下限，其中现场直接测量连续排放源是SOE的主要贡献者，是设施的子选择，其最大限度地减少了间歇性气动控制器的预期方法间差异和间歇性排放卸载的影响。在9个这样的设施中，VWLS表明，TFE估计的排放量系统地高于SOE（TFE与SOE的比率= 1.6，95% CI [1.2至2.1]）。在20个这样的设施中，VWLS表明，OFE估计的排放量系统地低于SOE（OFE与SOE的比率为0.41 [0.26至0.90]）。鉴于这些设施的SOE是排放的下限，这些结果表明，对于此类设施，OFE可能是一种不如SOE或TFE准确的方法。
This study presents the results of a campaign that estimated methane emissions at 268 gas production facilities in the Fayetteville shale gas play using onsite measurements (261 facilities) and two downwind methods - the dual tracer flux ratio method (Tracer Facility Estimate - TFE, 17 facilities) and the EPA Other Test Method 33a (OTM33A Facility Estimate - OFE, 50 facilities). A study onsite estimate (SOE) for each facility was developed by combining direct measurements and simulation of unmeasured emission sources, using operator activity data and emission data from literature. The SOE spans 0-403 kg/h and simulated methane emissions from liquid unloadings account for 88% of total emissions estimated by the SOE, with 76% (95% CI [51%-92%]) contributed by liquid unloading at two facilities. TFE and SOE show overlapping 95% CI between individual estimates at 15 of 16 (94%) facilities where the measurements were paired, while OFE and SOE show overlapping 95% CI between individual estimates at 28 of 43 (65%) facilities. However, variance-weighted least-squares (VWLS) regressions performed on sets of paired estimates indicate statistically significant differences between methods. The SOE represents a lower bound of emissions at facilities where onsite direct measurements of continuously emitting sources are the primary contributor to the SOE, a sub-selection of facilities which minimizes expected inter-method differences for intermittent pneumatic controllers and the impact of episodically-emitting unloadings. At 9 such facilities, VWLS indicates that TFE estimates systematically higher emissions than SOE (TFE-to-SOE ratio = 1.6, 95% CI [1.2 to 2.1]). At 20 such facilities, VWLS indicates that OFE estimates systematically lower emissions than SOE (OFE-to-SOE ratio of 0.41 [0.26 to 0.90]). Given that SOE at these facilities is a lower limit on emissions, these results indicate that OFE is likely a less accurate method than SOE or TFE for this type of facility.