Methane flux from flowback operations at a shale gas site.
Methane flux from flowback operations at a shale gas site.
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页岩气现场回流作业产生的甲烷通量。
DOI：
10.1080/10962247.2020.1811800
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
Shaw JT
中科院分区：
文献类型：
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作者：
Shaw JT
我们报告了甲烷（CH4）混合比和排放通量的测量结果，这些测量结果来自于英格兰兰开夏郡一个勘探页岩气开采设施的监测站的采样。2019年1月，在该设施的氮提升过程相关的冷排气期间，记录到环境ch4混合比率升高。这些过程用于清理井，以刺激目标页岩的天然气流动。使用三种独立的建模方法估算排放事件期间的ch4通量：高斯羽散（采用简单的高斯羽流反演和美国环保局OTM 33-A方法）和拉格朗日随机输运模型（WindTrax）。这三种方法在2019年1月估计的ch4通量峰值约为70 g s−1。采用简单高斯羽流模型、WindTrax和OTM-33A方法计算6 d排气期ch4总排放质量分别为2.9、4.2±1.4（1σ）和7.1±2.1（1σ）吨ch4。虽然通量接近在1σ不确定性范围内达成一致，但由于使用WindTrax模式允许对平流和气象稳定性进行明确建模，4.2（±1.4）吨ch4的估计是最可信的评估。这一质量与环境署根据页岩气田运营商向监管机构提供的排放数据计算出的甲烷通量一致（范围在2.7至6.8吨之间）。该研究首次提供了氮举升过程的ch4排放估算，并首次报道了英国页岩气现场的通量监测，并有助于评估全球页岩气作业的环境影响。该研究还为未来瞬态排放事件的监测应用和通量计算提供了前瞻性指导。含义：本文讨论了英国第一个水力压裂设施附近的大气测量，这对英国公众、媒体和政策都有很高的兴趣。这份手稿的重点是在一个星期的数据中，在页岩气站点的一个大型排气事件中，约有4吨甲烷排放到大气中，违反了环境许可。这些结果可能会被媒体报道，并可能影响英国水力压裂行业未来的政策决定。
We report measurements of methane (CH4) mixing ratios and emission fluxes derived from sampling at a monitoring station at an exploratory shale gas extraction facility in Lancashire, England. Elevated ambient CH4mixing ratios were recorded in January 2019 during a period of cold-venting associated with a nitrogen lift process at the facility. These processes are used to clear the well to stimulate flow of natural gas from the target shale. Estimates of CH4flux during the emission event were made using three independent modeling approaches: Gaussian plume dispersion (following both a simple Gaussian plume inversion and the US EPA OTM 33-A method), and a Lagrangian stochastic transport model (WindTrax). The three methods yielded an estimated peak CH4flux during January 2019 of approximately 70 g s−1. The total mass of CH4emitted during the six-day venting period was calculated to be 2.9, 4.2 ± 1.4(1σ) and 7.1 ± 2.1(1σ) tonnes CH4using the simple Gaussian plume model, WindTrax, and OTM-33A methods, respectively. Whilst the flux approaches all agreed within 1σ uncertainty, an estimate of 4.2 (± 1.4) tonnes CH4represents the most confident assessment due to the explicit modeling of advection and meteorological stability permitted using the WindTrax model. This mass is consistent with fluxes calculated by the Environment Agency (in the range 2.7 to 6.8 tonnes CH4), using emission data provided by the shale site operator to the regulator. This study provides the first CH4emission estimate for a nitrogen lift process and the first-reported flux monitoring of a UK shale gas site, and contributes to the evaluation of the environmental impacts of shale gas operations worldwide. This study also provides forward guidance on future monitoring applications and flux calculation in transient emission events.Implications: This manuscript discusses atmospheric measurements near to the UK’s first hydraulic fracturing facility, which has very high UK public, media, and policy interest. The focus of this manuscript is on a single week of data in which a large venting event at the shale gas site saw emissions of ~4 tonnes of methane to atmosphere, in breach of environmental permits. These results are likely to beresults are likely to be reported by the media and may influence future policy decisions concerning the UK hydraulic fracturing industry.