Flow rate and source reservoir identification from airborne chemical sampling of the uncontrolled Elgin platform gas release
Flow rate and source reservoir identification from airborne chemical sampling of the uncontrolled Elgin platform gas release
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DOI：
10.5194/amt-11-1725-2018
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发表时间：
2018-03-27
影响因子：
3.8
通讯作者：
Ryerson, Thomas B.
中科院分区：
文献类型：
--
作者：
Lee, James D.;Mobbs, Stephen D.;Ryerson, Thomas B.
2012年3月25日至5月16日，一次不受控制的天然气泄漏导致英国北海的Total Elgin井口和邻近的钻井和生产平台撤离。最初，泄漏的天然气和凝析油的大气流速知之甚少，阻碍了环境评估和油井控制工作。英国FAAM使用化学仪器的BAE-146研究飞机进行了六次飞行，以量化流速。通过假设羽流可以用高斯分布来模拟，采用两种不同的求解方法来计算流量：垂直方向的高斯拟合法和完全混合层的拟合法。当使用两种求解方法时，它们相互比较的误差在6%以内，这在综合误差范围内。2012年3月30日第一次飞行的数据显示，流量为1.3+/-0.2公斤甲烷S(-1)，到2012年4月17日第二次飞行时，流量下降到不到一半。天然气中的Delta(13)C-CH4含量为-43‰，表明气源不太可能来自5.5公里处的主高压高温埃尔金气田，而更有可能来自4.2公里处的上覆Hod组。这被认为比高压埃尔金油田更小、更易于管理，因此应对战略要简单得多。第一次飞行是在井喷后5天内进行的，并允许在采样后48小时内进行流速估计，随后不久就对增量C-13(CH4)进行了表征，表明快速反应能力的潜力广泛适用于未来令人关注的大气排放。埃尔金流量的知识有助于为随后的决策提供信息。这项研究表明，使用适当设计的气载烟羽采样策略进行泄漏评估非常适合直接进入困难或潜在危险的环境。这样的测量还允许对潜在影响进行不带偏见的监管评估，独立于排放方，对时间表进行评估，以便为行业决策者提供信息，并帮助政府制定快速反应计划。
An uncontrolled gas leak from 25 March to 16 May 2012 led to evacuation of the Total Elgin wellhead and neighbouring drilling and production platforms in the UK North Sea. Initially the atmospheric flow rate of leaking gas and condensate was very poorly known, hampering environmental assessment and well control efforts. Six flights by the UK FAAM chemically instrumented BAe-146 research aircraft were used to quantify the flow rate. The flow rate was calculated by assuming the plume may be modelled by a Gaussian distribution with two different solution methods: Gaussian fitting in the vertical and fitting with a fully mixed layer. When both solution methods were used they compared within 6 % of each other, which was within combined errors. Data from the first flight on 30 March 2012 showed the flow rate to be 1.3 +/- 0.2 kg CH4 s(-1), decreasing to less than half that by the second flight on 17 April 2012. delta(13) C-CH4 in the gas was found to be -43 parts per thousand, implying that the gas source was unlikely to be from the main high pressure, high temperature Elgin gas field at 5.5 km depth, but more probably from the overlying Hod Formation at 4.2 km depth. This was deemed to be smaller and more manageable than the high pressure Elgin field and hence the response strategy was considerably simpler. The first flight was conducted within 5 days of the blowout and allowed a flow rate estimate within 48 h of sampling, with delta C-13(CH4) characterization soon thereafter, demonstrating the potential for a rapid -response capability that is widely applicable to future atmospheric emissions of environmental concern. Knowledge of the Elgin flow rate helped inform subsequent decision making. This study shows that leak assessment using appropriately designed airborne plume sampling strategies is well suited for circumstances where direct access is difficult or potentially dangerous. Measurements such as this also permit unbiased regulatory assessment of potential impact, independent of the emitting party, on timescales that can inform industry decision makers and assist rapid-response planning by government.