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，通过断层带中的流体迁移来限制应力传递的方法很少。然而，研究诱发地震提供了一个有价值的机会，试图回答上述问题，因为增加的人为贡献的应力加载或卸载注入和提取环境可以更容易地限制比自然构造断层加载。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。 这项研究的首要目标是利用密集的地震台站、高分辨率干涉合成孔径雷达和全球定位系统观测、井压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转移。我们将重点关注加拿大不列颠哥伦比亚省Dawson Creek附近的一个场地，该场地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ML 4.5诱发地震。为了在运行参数和地震生产之间建立震级可预测的关系，我们将：· 使用环境噪声/地震层析成像以及剪切波分裂技术来检测ML 4.5诱发地震和余震序列周围断层结构的变化，以及36个月研究期的剩余时间。 创建增强的地震目录和震源参数估计，将地震的空间/时间演变与不断变化的破坏和流体运动联系起来。 调查诱发地震的震源参数标度关系以及随时间变化的速度变化对估计值的影响。 研究三维速度结构的时间依赖性，以研究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，以及地震活动与长期地面变形之间的相关性，研究地壳岩石的弹性特性。 使用地震和大地测量观测来测试和约束水文地质和孔隙弹性模型;使用模型来预测地震成核的注入条件。 通过地下水化学和地震活动性的变化调查关系，包括潜在的远程触发地震计划的项目持续时间总计36个月，申请的资金包括支持一名博士生，一名学生助理，博士生的会议旅行，以及安装费用，以增加目前在研究现场的地震台站的初步网络，增加五个额外的地震仪。以及三个GPS/GNSS接收器。

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.