Monitoring of offshore geological carbon storage integrity: Implications of natural variability in the marine system and the assessment of anomaly detection criteria
Monitoring of offshore geological carbon storage integrity: Implications of natural variability in the marine system and the assessment of anomaly detection criteria
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DOI：
10.1016/j.ijggc.2017.06.020
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发表时间：
2017-09
影响因子：
3.9
通讯作者：
J. Blackford;Y. Artioli;J. Clark;L. Mora
中科院分区：
文献类型：
--
作者：
J. Blackford;Y. Artioli;J. Clark;L. Mora
确保海上地质封存所需的有效监测计划的设计需要了解海洋碳酸盐化学的变异性和异质性。在缺乏足够的观测数据和空间和季节外推数据的情况下，模型可以发挥重要作用。在这项研究中，以前评估的水动力-地球化学模型被用来模拟碳酸盐化学，特别是在海底附近的pH异质性。使用三个对比鲜明的地区，季节性和短期的变化进行了分析和标准，可以被认为是异常碳酸盐化学的指标确定。然后，这些标准进行测试，施加一些随机DIC扰动的模型数据，代表了全面的泄漏情况。最后，确定了制定监测战略的最佳标准和一般规则。检测标准将因地点而异，并随季节而变化，在动态较低的时期，监测可能更有效。分析表明，通过使用高频率，每小时监测一次的异常，小到0.01个pH单位或更小，可以成功地与自然变异区分开来，从而可以检测到小的泄漏或距离泄漏源。相反，保证不泄漏将是深刻的。在较深的站点的检测可能是更有效的比在浅的站点，近床系统是密切耦合到表面过程。虽然这项研究是以北海地质封存目标地点为基础的，但模型和一般结论适用于大陆架上的大多数近海封存地点。
The design of efficient monitoring programmes required for the assurance of offshore geological storage requires an understanding of the variability and heterogeneity of marine carbonate chemistry. In the absence of sufficient observational data and for extrapolation both spatially and seasonally, models have a significant role to play. In this study a previously evaluated hydrodynamic-biogeochemical model is used to characterise carbonate chemistry, in particular pH heterogeneity in the vicinity of the sea floor. Using three contrasting regions, the seasonal and short term variability are analysed and criteria that could be considered as indicators of anomalous carbonate chemistry identified. These criteria are then tested by imposing a number of randomised DIC perturbations on the model data, representing a comprehensive range of leakage scenarios. In conclusion optimal criteria and general rules for developing monitoring strategies are identified. Detection criteria will be site specific and vary seasonally and monitoring may be more efficient at periods of low dynamics. Analysis suggests that by using high frequency, sub-hourly monitoring anomalies as small as 0.01 of a pH unit or less may be successfully discriminated from natural variability – thereby allowing detection of small leaks or at distance from a leakage source. Conversely assurance of no leakage would be profound. Detection at deeper sites is likely to be more efficient than at shallow sites where the near bed system is closely coupled to surface processes. Although this study is based on North Sea target sites for geological storage, the model and the general conclusions are relevant to the majority of offshore storage sites lying on the continental shelf.