Speciation of VOC emissions related to offshore North Sea oil and gas production
Speciation of VOC emissions related to offshore North Sea oil and gas production
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DOI：
10.5194/acp-2020-1099
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发表时间：
2020-10
影响因子：
6.3
通讯作者：
S. Wilde;P. Dominutti;G. Allen;S. Andrews;Prudence Bateson;S. Bauguitte;R. Burton;Ioana Colfescu;J. France;J. Hopkins;La-mei Huang;A. Jones;T. Lachlan-Cope;James D. Lee;A. Lewis;S. Mobbs;Alexandra Weiss;S. Young;R. Purvis
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文献类型：
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作者：
S. Wilde;P. Dominutti;G. Allen;S. Andrews;Prudence Bateson;S. Bauguitte;R. Burton;Ioana Colfescu;J. France;J. Hopkins;La-mei Huang;A. Jones;T. Lachlan-Cope;James D. Lee;A. Lewis;S. Mobbs;Alexandra Weiss;S. Young;R. Purvis
抽象的。北海是欧洲主要的油气盆地，目前产量占全球石油供应量的3%-4%。尽管如此，对该地区大气排放性质的观测限制很少，大多数信息来自自下而上的清单估计。这项研究报告了对北海O&G产区挥发性有机化合物(VOCs)的气载测量结果。在四个地理区域测定了海上油田主要采油产品(油、天然气、凝析油、混合油)的VOC源排放特征。所有地区测得的异戊烷与正戊烷(IC5/NC5)的比值为0.89-1.24，作为O&G活动的确认性指标。低碳烷烃(乙烷、丙烷、丁烷、戊烷)是所有四个地区排放的主要物种；然而，总的羟基反应活性以不饱和物种为主，如1，3-丁二烯，尽管它们的丰度相对较低。苯与甲苯的比率表明，只有在南风或西南风期间才能看到北海南部产气地区可能的陆地燃烧排放源的影响。然而，所有其他地区都表现出了O&G业务的特征。乙烷(C2H6)和甲烷(CH4)之间的相关性证实了O&G产物是CH4的主要来源。增加比(ΔC2H6/ΔCH4)介于0.03-0.18之间，表明干湿两种甲烷排放源的排放都具有空间依赖性。过量的摩尔分数表明，与CH4相比，深水石油开采导致较高碳数烷烃的排放比例较大，而天然气开采(通常从浅水开采)导致以CH4为主的排放的复杂程度较低。测得的VOC来源分布与英国国家大气排放清单(NAEI)中的石油生产类似，低碳烷烃与丙烷的摩尔比一致。观察值和清单之间的最大差异是单芳烃化合物，突出表明这些物种目前没有完全列入清单。这些结果表明，VOC测量可用于区分O&G部门内的独特来源，并概述北海VOC的形态。
Abstract. The North Sea is Europe's key oil and gas (O&G) basin with the output currently meeting 3 %–4 % of global oil supply. Despite this, there are few observational constraints on the nature of atmospheric emissions from this region, with most information derived from bottom-up inventory estimates. This study reports on airborne measurements of volatile organic compounds (VOCs) emitted from O&G-producing regions in the North Sea. VOC source emission signatures for the primary extraction products from offshore fields (oil, gas, condensate, mixed) were determined in four geographic regions. Measured iso-pentane to n-pentane (iC5 / nC5) ratios were 0.89–1.24 for all regions, used as a confirmatory indicator of O&G activities. Light alkanes (ethane, propane, butane, pentane) were the dominant species emitted in all four regions; however, total OH reactivity was dominated by unsaturated species, such as 1,3-butadiene, despite their relatively low abundance. Benzene to toluene ratios indicated the influence of possible terrestrial combustion sources of emissions in the southern, gas-producing region of the North Sea, seen only during south or south-westerly wind episodes. However, all other regions showed a characteristic signature of O&G operations. Correlations between ethane (C2H6) and methane (CH4) confirmed O&G production to be the primary CH4 source. The enhancement ratio (ΔC2H6/ΔCH4) ranged between 0.03–0.18, indicating a spatial dependence on emissions with both wet and dry CH4 emission sources. The excess mole fraction demonstrated that deepwater oil extraction resulted in a greater proportion of emissions of higher carbon number alkanes relative to CH4, whereas gas extraction, typically from shallow waters, resulted in a less complex mix of emissions dominated by CH4. The VOC source profiles measured were similar to those in the UK National Atmospheric Emissions Inventory (NAEI) for oil production, with consistency between the molar ratios of light alkanes to propane. The largest discrepancies between observations and the inventory were for mono-aromatic compounds, highlighting that these species are not currently fully captured in the inventory. These results demonstrate the applicability of VOC measurements to distinguish unique sources within the O&G sector and give an overview of VOC speciation over the North Sea.