States of In Situ Stress in the Duvernay East Shale Basin and Willesden Green of Alberta, Canada: Variable In Situ Stress States Effect Fault Stability
States of In Situ Stress in the Duvernay East Shale Basin and Willesden Green of Alberta, Canada: Variable In Situ Stress States Effect Fault Stability
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加拿大艾伯塔省 Duvernay East 页岩盆地和 Willesden Green 的地应力状态：可变的地应力状态影响断层稳定性
DOI：
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
T. Hauck
中科院分区：
文献类型：
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作者：
Luyi W. Shen;D. Schmitt;Ruijia Wang;T. Hauck
断层滑动受断层面上的正向和剪切力控制。要充分了解影响诱发地震活动的因素，需要地应力张量和流体压力的定量知识。我们对加拿大红鹿市附近水力压裂活跃的200×200公里区域的这些变量进行了分析。在2019年3月4日当地居民感受到Mw 3.8/ML 4.2地震之前，该地区的诱发地震活动水平普遍较低。我们使用地球物理测井和目标Duvernay地层内的压力测试来构建环境孔压、垂直和最小水平应力的地图。最大水平应力由震源机制反演和基于井眼的估算方法约束。我们发现，很大范围的取向都容易发生滑移，流体压力的微小扰动会促进位移。这表明，目标地层中孔隙流体压力的差异变化可能提供了滑动敏感性的量度；绘制了研究区的地图。高敏感性地区与经历较高水平诱发地震活动的地区相关，但威勒斯登格林油田除外，该油田的敏感性类似地升高，水力压裂作业也很活跃。这些方法和结果表明，从一组实际现场测量中获得的更多定量约束地应力如何有助于评估断层稳定性和制定滑动敏感性的度量标准。
Fault slip is controlled by the normal and shear tractions on a fault plane. A full understanding of the factors influencing induced seismicity requires quantitative knowledge of the in situ stress tensor and fluid pressure. We analyze these variables for a 200 × 200 km region with active hydraulic fracturing near the city of Red Deer, Canada. The levels of induced seismicity in the area were generally low before March 4, 2019, when local residents felt the MW 3.8/ML 4.2 event. We use geophysical logs and pressure tests within the targeted Duvernay Formation to construct maps of ambient pore pressure, vertical and minimum horizontal stresses. The maximum horizontal stress is constrained by the focal mechanism inversion and borehole‐based estimation method. We find that a broad range of orientations are susceptible to slip and small perturbations of fluid pressure would promote displacement. This suggests that the differential variations in pore fluid pressure in the target formation may provide a metric of slip susceptibility; a map for the study area is developed. Areas of high susceptibility correlate with those experiencing higher levels of induced seismicity, except for the Willesden Green oil field that has similarly elevated susceptibility and active hydraulic fracturing operations. The methods and results demonstrate how more quantitatively constrained in situ stresses developed from an ensemble of real field measurements can assist in assessing fault stability and in developing metrics for slip susceptibility.
DOI：
10.1029/2019jb018794
发表时间：
2020-01
期刊：
Journal of Geophysical Research: Solid Earth
影响因子：
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作者：
T. Kettlety;J. Verdon;Maximilian J. Werner;J. Kendall
通讯作者：
T. Kettlety;J. Verdon;Maximilian J. Werner;J. Kendall