How big is a small earthquake? Challenges in determining microseismic magnitudes
How big is a small earthquake? Challenges in determining microseismic magnitudes
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DOI：
10.3997/1365-2397.n0015
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发表时间：
2019-02
期刊：
影响因子：
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通讯作者：
Jeffrey M. Kendall;A. Butcher;A. Stork;J. Verdon;Richard Luckett;B. Baptie
中科院分区：
文献类型：
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作者：
Jeffrey M. Kendall;A. Butcher;A. Stork;J. Verdon;Richard Luckett;B. Baptie
地震震级难以准确估计。在评估小型地震时尤其如此：例如，由页岩气开采、二氧化碳和废水储存以及增强型地热系统等人类活动引起的地震。不确定性是由一系列问题造成的，包括：使用哪个“震级”尺度；用什么仪器记录地震？如何部署这些仪器；以及源和接收器之间地球的异质性。误差在尺度上可能大于一个数量级。对于非常小的地震，这通常不太值得关注。然而，偶尔地表也能感觉到由人类活动引起的更大的地震。这导致监管框架要求在地震达到感觉点之前对地震震级进行准确评估。因此，为了监测和减轻感觉到的地震活动，需要实时计算准确的地震震级。诱发地震活动的监管监测正成为涉及增产或储层的油藏项目成功开发的关键问题。在这里，我们讨论了实施这种油藏监测的挑战，并提供了一种建议的监测策略。
Earthquake magnitudes are surprisingly difficult to estimate accurately. This is especially true when evaluating small earthquakes: for example, those caused by human activities such as shale gas stimulation, CO2 and waste water storage, and enhanced geothermal systems. Uncertainties are created by a range of issues including: which ‘magnitude’ scale is used; what type of instrument records the earthquake; how the instruments are deployed; and the heterogeneity of the Earth between the source and the receivers. Errors can be larger than an order of magnitude in scale. For very small earthquakes this is not usually of much concern. However, occasionally, larger earthquakes induced by human activity are felt at the surface. This has led to regulatory frameworks that require accurate assessment of earthquake magnitudes before they reach the point of being felt. Hence, to monitor and mitigate felt seismicity there is a need to calculate accurate earthquake magnitudes in real time. Regulatory monitoring of induced seismicity is becoming a key issue in the successful development of reservoir projects that involve stimulation or storage. Here, we discuss the challenges with implementing such reservoir monitoring, and provide a suggested monitoring strategy.