Investigating the role of elastostatic stress transfer during hydraulic fracturing-induced fault activation
Investigating the role of elastostatic stress transfer during hydraulic fracturing-induced fault activation
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DOI：
10.1093/gji/ggz080
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发表时间：
2019-05-01
影响因子：
2.8
通讯作者：
Budge, Jessica
中科院分区：
文献类型：
--
作者：
Kettlety, Tom;Verdon, James P.;Budge, Jessica
我们研究水力压裂过程中产生地震活动的物理过程。流体过程（孔隙压力和孔隙弹性应力的增加）通常被认为是主要驱动因素。然而，最近的一些研究表明，弹性应力相互作用可能会显着促进进一步的地震活动。在这项工作中，我们使用水力压裂期间获得的微震数据集来计算断层激活和诱发地震活动期间的弹性应力传递。我们发现，弹性应力变化可能微弱地促进了初始失效，但后来应力变化通常起到抑制进一步滑动的作用。发现来自紧密簇内的源是累积弹性应力变化的最重要贡献者。考虑到估计的地应力场，需要相对较大的孔隙压力增加才能达到这些断层的破坏范围（大约 10 MPa）。该阈值远大于本研究中发现的可靠累积弹性应力变化，绝大多数事件接收的正 Delta CFS 不超过 0.1 MPa，进一步表明弹性应力变化不是重要的驱动因素，并且需要与加压流体相互作用才能引发故障。因此，注入井附近小事件的累积应力转移似乎在附近断层的重新激活中没有发挥重要作用。
We investigate the physical processes that generate seismicity during hydraulic fracturing. Fluid processes (increases in pore pressure and poroelastic stress) are often considered to be the primary drivers. However, some recent studies have suggested that elastic stress interactions may significantly contribute to further seismicity. In this work we use a microseismic data set acquired during hydraulic fracturing to calculate elastic stress transfer during a period of fault activation and induced seismicity. We find that elastic stress changes may have weakly promoted initial failure, but at later times stress changes generally acted to inhibit further slip. Sources from within tight clusters are found to be the most significant contributor to the cumulative elastic stress changes. Given the estimated in situ stress field, relatively large increases in pore pressure are required to reach the failure envelope for these faults-on the order of 10 MPa. This threshold is far greater than the reliable cumulative elastic stress changes found in this study, with the vast majority of events receiving no more than 0.1 MPa of positive Delta CFS, further indicating that elastic stress changes were not a significant driver, and that interaction with the pressurized fluid was required to initiate failure. Thus, cumulative stress transfer from small events near the injection well does not appear to play a significant role in the reactivation of nearby faults.