Investigating stress transfer via fluids in a hydraulic fracturing environment using seismic, geodetic, and hydrological observations coupled with poroelastic modeling techniques

在研究天然地震时，通过断裂带中的流体迁移来约束应力传递的方法很少。然而，研究诱发地震提供了一个尝试回答上述问题的宝贵机会，因为在注入和提取环境中，人为对应力加载或卸载的额外贡献比自然构造断层加载更容易受到约束。自2011年以来，加拿大西部沉积盆地的地震活动急剧增加，当时非常规能源生产活动急剧增加。这项研究的总体目标将是利用密集的地震台阵列、高分辨率InSAR和GPS观测、井压力和地球化学分析以及建模方法，将注入和回流流体压力和速率形式的输入应力与地震发生的关系联系起来，以限制地壳中的应力传递。我们将重点关注加拿大不列颠哥伦比亚省道森克里克附近的一个地点，那里对抽水的地震反应强烈，包括2018年11月30日发生的与附近一口井的水力压裂刺激有关的4.5级地震。为了在运行参数和地震产生之间建立震级可预测的关系，我们将：·使用环境噪声/地震层析成像以及横波分裂技术来检测ML 4.5诱发地震和余震序列周围断层结构的变化，以及为期36个月的剩余研究·创建增强的地震目录和震源参数估计，以将地震的时空演变与不断演变的破坏和流体运动联系起来·调查诱发地震的震源参数比例关系和随时间变化的速度变化对估计值的影响·调查三维速度结构的时间相关性，以调查与震源性质和注入活动的相关性·利用高分辨率大地测量观测和对地下水波动和注入流体的响应调查地壳岩石的弹性性质，以及地震活动与较长期地面变形之间的相关性·使用地震和大地测量观测来测试和约束水文地质和孔洞弹性模型；使用模型预测地震成核的注入条件·通过地下水化学和地震活动的变化，包括潜在的远程触发地震，调查地震与地震之间的关系计划的项目持续时间总计36个月，请拨的资金包括支助一名博士生、一名学生助理、博士生的会议旅费，以及用另外五台地震仪以及三台全球定位系统/全球导航卫星系统接收器来扩大研究地点现有地震台站初步网络的安装费用。

There are few ways to constrain stress transfer via fluid migration in fault zones when studying natural earthquakes. However, studying induced earthquakes provides a valuable opportunity to try and answer the above question, because the added anthropogenic contribution to stress loading or unloading in injection and extraction environments can be constrained more easily than natural tectonic fault loading. Seismicity has increased drastically in the Western Canadian Sedimentary Basin since 2011, when unconventional energy production activity increased drastically. The overarching aim of this study will be to use a dense array of seismic stations, high resolution InSAR and GPS observations, well pressure and geochemical analyses, and modeling approaches to link input stresses in the form of injection and flowback fluid pressures and rates to a relationship for earthquake occurrence to constrain stress transfer in the crust. We will focus on a site near Dawson Creek, British Columbia, Canada where seismic response to pumping is vigorous, including a ML 4.5 induced earthquake related to hydraulic fracture stimulation of a nearby well that occurred on the 30th of November, 2018. In order to work toward establishing a magnitude-predictable relationship between operational parameters and earthquake production, we will:• Use both ambient noise/seismic tomography, as well as shear wave splitting techniques to detect changes in fault structure surrounding the ML 4.5 induced earthquake and aftershock sequence, as well as the remainder of a 36-month study period • Create an enhanced earthquake catalog and source parameter estimates to link the spatial/temporal evolution of earthquakes to evolving damage and fluid movement• Investigate the source parameter scaling relationships of induced earthquakes and the influence of time-dependent velocity changes on estimated values• Investigate the time dependence of 3D velocity structure to investigate correlations with earthquake source properties and injection activity• Investigate elastic properties of crustal rocks using high-resolution geodetic observations and responses to groundwater fluctuations and injected fluids, as well as the correlation between seismic activity and longer-term ground deformation• Use seismic and geodetic observations to test and constrain hydrogeological and poroelastic models; use models to predict the injection conditions under which earthquakes will nucleate• Investigate relationships through changes in groundwater chemistry and seismicity, including potentially remotely triggered earthquakesThe planned project duration totals 36 months, and requested funds include support for one PhD student, one student assistant, conference travel for the PhD student, and installation costs to augment the preliminary network of seismic stations currently in place at the study site with five additional seismometers, as well as three GPS/GNSS receivers.