Spectral Characteristics of Hydraulic Fracturing-Induced Seismicity Can Distinguish between Activation of Faults and Fractures
Spectral Characteristics of Hydraulic Fracturing-Induced Seismicity Can Distinguish between Activation of Faults and Fractures
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DOI：
10.1785/0220230024
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发表时间：
2023-05
影响因子：
3.3
通讯作者：
N. Igonin;D. Trugman;Keyla Gonzalez;D. Eaton
中科院分区：
文献类型：
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作者：
N. Igonin;D. Trugman;Keyla Gonzalez;D. Eaton
分析地震谱有助于了解震源特征，如应力降和破裂复杂性。人们对探讨自然和人为地震事件中断层破裂的异同越来越感兴趣。在这里，我们分析了一个浅层埋地检波器阵列的波形数据，该检波器阵列记录了艾伯塔省Fox Creek附近一次水力压裂作业期间的地震活动。从4000个震级在0到3.2之间的事件的质量控制目录开始，我们使用考虑传感器响应的带宽限制性质的方法估计源谱角频率。发现应力降值近似自相似，但具有轻微的幅度依赖性，其中较大的事件具有较高的应力降（~ 10 MPa）。对相对角频率的仔细分析表明，单个断层和裂缝段的相对角频率随着时间的推移经历了系统的变化，这表明应力状态可能发生了变化。基于高频和低频含量相对于Brune模型的相对比例对源光谱进行聚类分析，进一步表明事件复杂性随时间的变化而变化。此外，断层产生的地震的应力降值系统地大于裂缝。综上所述，这些结果表明，水力压裂激活的特征随着时间的推移会发生可观察到的源行为变化，并根据其发生的构造特征的方向、规模和结构表现出不同的性质。
Analysis of earthquake spectra can aid in understanding source characteristics like stress drop and rupture complexity. There is growing interest in probing the similarities and differences of fault rupture for natural and human-induced seismic events. Here, we analyze waveform data from a shallow, buried geophone array that recorded seismicity during a hydraulic fracturing operation near Fox Creek, Alberta. Starting from a quality-controlled catalog of 4000 events between magnitude 0 and 3.2, we estimate source-spectral corner frequencies using methods that account for the band-limited nature of the sensor response. The stress-drop values are found to be approximately self-similar, but with a slight magnitude dependence in which larger events have higher stress drop (∼10 MPa). Careful analysis of the relative corner frequencies shows that individual fault and fracture segments experienced systematic variations in relative corner frequency over time, indicating a possible change in the stress state. Clustering analysis of source spectra based on the relative proportion of high- and low-frequency content relative to the Brune model further shows that event complexity evolves over time. In addition, the faults produce earthquakes with systematically larger stress-drop values than the fractures. Combined, these results indicate that the features activated by hydraulic fracturing experience observable changes in source behavior over time and exhibit different properties depending on the orientation, scale, and fabric of the structural feature on which they occur.