Earthquakes Triggered by Fluid Diffusion and Boosted by Fault Reactivation in Weiyuan, China Due to Hydraulic Fracturing
Earthquakes Triggered by Fluid Diffusion and Boosted by Fault Reactivation in Weiyuan, China Due to Hydraulic Fracturing
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DOI：
10.1029/2021jb022963
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发表时间：
2021-02
期刊：
影响因子：
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通讯作者：
Minhan Sheng;R. Chu;Zhigang Peng;Zigen Wei;Xiangfang Zeng;Qingdong Wang;Yong Wang
中科院分区：
文献类型：
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作者：
Minhan Sheng;R. Chu;Zhigang Peng;Zigen Wei;Xiangfang Zeng;Qingdong Wang;Yong Wang
水力压裂在世界各地引发了小型到中型地震。识别微震活动的时空演化对于理解控制水力压裂诱发地震活动的物理过程非常重要。在这项研究中，我们使用自动程序从1年临时部署记录的连续地震数据中建立了增强的地震目录，并重新定位了中国四川盆地南部威远页岩气区块的18，663次地震。我们的目录，最大ML为3.5，完整性震级（Mc）为0.4，这是中国国家地震数据中心（NEDC）标准中列出的事件的2.23倍。大多数地震聚集在水力压裂威尔斯井附近，并在南北方向上描绘出许多预先存在的断层。微震的时空演化表明流体扩散过程是该地区地震活动的主要驱动力。快速地震迁移模式表明，断层带内的渗透性可能受到断层阀行为的影响，并因地震破裂过程而增强。我们发现，古滕贝格-里希特B-值系统地增加与深度，和B-值更远离水力压裂垫一般是低的，特别是对于三股具有相对较高的迁移速度。研究结果证实了渭源地震群是由水力压裂引起的，断层的再活化是流体流动的管道网络，促使地震在离水力压裂垫较远的地方触发。该研究为川南地区水力压裂诱发地震提供了新的证据，并加深了对注水诱发地震的认识。
Hydraulic fracturing has induced small‐to‐moderate‐size earthquakes around the world. Identifying spatio‐temporal evolution of microseismicity is important for understanding the physical processes that control hydraulic fracturing‐induced seismicity. In this study, we build an enhanced earthquake catalog from continuous seismic data recorded by 1‐year temporary deployment with an automatic procedure and relocate 18,663 earthquakes in the Weiyuan shale gas block in the southern Sichuan Basin, China. Our catalog, with a maximum ML of 3.5, has a completeness magnitude (Mc) of 0.4, which is ∼23 times more events than listed in the standard National Earthquake Data Center (NEDC) of China. Most earthquakes are clustered near hydraulic fracturing wells and delineate many pre‐existing faults in the north‐south direction. The space‐time evolution of microearthquakes indicates fluid diffusion processes as the primary drivers for seismicity in this region. The fast earthquake migration patterns show that permeability within a fault zone could be affected by fault‐valve behaviors and enhanced by earthquake rupture process. We find that the Gutenberg‐Richter b‐values increase systematically with depth, and b‐values further away from hydraulic fracturing pads are generally low, especially for three strands with relatively high migration velocities. Our results confirm that earthquake clusters in Weiyuan are induced by hydraulic fracturing and the reactivated faults act as conduit networks for fluid flow, which promote triggering of earthquakes further away from the hydraulic fracturing pad. This study provides additional evidence for hydraulic fracturing‐induced earthquake in the southern Sichuan Basin and advances our understanding of injection induced earthquakes.