Depth migration of seasonally induced seismicity at The Geysers geothermal field
Depth migration of seasonally induced seismicity at The Geysers geothermal field
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DOI：
10.1002/2016gl069546
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发表时间：
2016-06-28
影响因子：
5.2
通讯作者：
Burgmann, Roland
中科院分区：
文献类型：
--
作者：
Johnson, Christopher W.;Totten, Eoghan J.;Burgmann, Roland
注入流体的地震活动提供了对加利福尼亚州间歇泉(Tg)地热储集层水力传导裂缝网络的洞察。当注入的流体冷却岩石并增加孔隙压力时，Tg处的诱发地震是热弹性和孔弹性应力共同作用的结果。M>；=1.5地震活动的时空演化被描述为Tg西北部和东南部地区深度的函数，利用流行型余震序列模型建立了随时间变化的地震率。地震活动和注入遵循一个年度周期，该周期在冬季的几个月达到峰值，并与深度相关。结果表明，在注入深度以下有3公里的时间滞后。当流体渗入储集层时，注水是地震活动的主要原因。我们的结果表明，由水力传导断层组成的陡峭的裂缝网络允许流体运移到注入点以下几公里处。
Seismicity from injected fluids provides insight into the hydraulically conductive fracture network at The Geysers (TG), California, geothermal reservoir. Induced earthquakes at TG result from both thermoelastic and poroelastic stresses as injected fluids cool the rocks and increase pore pressure. The spatiotemporal evolution of M >= 1.5 seismicity is characterized as a function of depth in the northwest and southeast regions of TG to develop time-dependent earthquake rates using an epidemic-type aftershock sequence model. The seismicity and injection follow an annual cycle that peaks in the winter months and is correlated by depth. The results indicate a time lag of 3 km below the injection depth. Water injection is the main cause of seismicity as fluids penetrate into the reservoir. Our results suggest that a steeply dipping fracture network of hydraulically conductive faults allows fluid migration to a few kilometers below the point of injection.