Stress Transfer From Opening Hydraulic Fractures Controls the Distribution of Induced Seismicity
Stress Transfer From Opening Hydraulic Fractures Controls the Distribution of Induced Seismicity
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DOI：
10.1029/2019jb018794
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发表时间：
2020-01
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影响因子：
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通讯作者：
T. Kettlety;J. Verdon;Maximilian J. Werner;J. Kendall
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文献类型：
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作者：
T. Kettlety;J. Verdon;Maximilian J. Werner;J. Kendall
了解由于流体注入导致断层重新激活的主要物理过程对于制定避免和减轻注入诱发地震活动的策略至关重要。注入诱发的地震活动对多个行业构成风险，包括水力压裂、地热增产、油田废物处理以及碳捕获和储存，其中水力压裂与一些最高震级的诱发地震（M>5）有关。因此，在全球范围内实施了严格的监管计划，以限制与运营相关的地震活动。在英国，目前有一个非常严格的“交通灯”系统。2018年10月至12月，在英国兰开夏郡普雷斯顿新路的PNR‐ 1 z井注入期间，多次采用了这些程序。随着注入的进行，操作员发现，阶段与孕震平面结构相互作用，解释为断层带，发生了几次ML>0.5的事件。微震活动沿沿着这一平面结构聚集在一起，其方式不能通过孔隙压力扩散或水力裂缝生长来解释。相反，我们调查的作用，静态弹性应力转移所产生的拉伸开放的水力压裂。我们发现，微震活动的空间分布与从拉伸裂缝开口接收正Mohr-Coulomb应力变化的区域密切相关，而接收负Mohr-Coulomb应力变化的区域是静止的。我们的结论是，由于拉伸水力裂缝开放的应力起着重要的作用，在控制诱发地震活动的时空分布。
Understanding the dominant physical processes that cause fault reactivation due to fluid injection is vital to develop strategies to avoid and mitigate injection‐induced seismicity. Injection‐induced seismicity is a risk for several industries, including hydraulic fracturing, geothermal stimulation, oilfield waste disposal and carbon capture and storage, with hydraulic fracturing having been associated with some of the highest magnitude induced earthquakes ( M>5 ). As such, strict regulatory schemes have been implemented globally to limit the felt seismicity associated with operations. In the UK, a very strict “traffic light” system is currently in place. These procedures were employed several times during injection at the PNR‐1z well at Preston New Road, Lancashire, UK, from October to December 2018. As injection proceeded, it became apparent to the operator that stages were interacting with a seismogenic planar structure, interpreted as a fault zone, with several ML>0.5 events occurring. Microseismicity was clustered along this planar structure in a fashion that could not readily be explained through pore pressure diffusion or hydraulic fracture growth. Instead, we investigate the role of static elastic stress transfer created by the tensile opening of hydraulic fractures. We find that the spatial distributions of microseismicity are strongly correlated with areas that receive positive Mohr‐Coulomb stress changes from the tensile fracture opening, while areas that receive negative Mohr‐Coulomb stress change are quiescent. We conclude that the stressing due to tensile hydraulic fracture opening plays a significant role in controlling the spatiotemporal distribution of induced seismicity.