Induced earthquake source process imaging and groundwater chemistry monitoring in the Western Canada sedimentary basin

在过去5年中，北美非常规石油和天然气开采过程中注入的流体可能引发的地震数量急剧增加，包括以前地震平静的地区。特别是，不列颠哥伦比亚省东北部和阿尔伯塔发生的与水力压裂作业相关的4级或更大地震导致油井生产暂时关闭，并引起当地社区的安全担忧。尽管地震监测网络日益密集，但注水诱发地震的详细震源过程和触发阈值仍然是地震危险性评估和减灾的关键挑战。在这个项目中，我们建议将创新的地球物理，水文地质和地球化学监测技术和数值工具，定量图像和模型诱导地震活动源过程中的两个水力压裂威尔斯和一个处置井在东北部BC省和西部阿尔伯塔。在每个目标地点，我们将安装一个密集的阵列，由宽带地震仪和综合地震大地测量系统组成，用于记录诱发地震的地震仪，并安装角反射器，用于增强干涉测量卫星孔径雷达地面运动成像。我们还将在目标地点进行地下水化学和同位素调查，以确定与流体注入有关的时间变化，重点是潜在的地震前兆信号。现场观测将用于约束孔隙弹性模型，以模拟注入引起的流体压力和固体基质应力变化，并设计注入策略，以减少在既存断层上触发地震滑动的可能性。本项目的研究成果将为我们的支持机构GSC的公共政策制定以及省级油气委员会的监管政策调整提供公正的科学知识。

In the past 5 years, there has been a drastic increase in the number of earthquakes potentially induced by fluid injection during unconventional oil and gas extraction in North America, including previously seismically quiescent areas. In particular, the occurrences of magnitude 4 and greater earthquakes associated with hydraulic fracturing operations in northeast British Columbia and Alberta has led to temporarily shut-down of well production and caused safety concerns among local communities. Despite the densification of seismic monitoring network, the detailed source process and triggering threshold of injection induced earthquakes remains a critical challenge to seismic hazard assessment and mitigation. In this project, we proposed to incorporate innovative geophysical, hydrogeological and geochemical monitoring techniques and numerical tools, to quantitatively image and model induced seismicity source processes at two hydraulic fracturing wells and one disposal well in northeast BC and west Alberta. At each target site, we will install a dense array composed of broadband seismometers and integrated seismo-geodetic systems for recording seismographs of induced earthquakes, and angled reflectors for enhanced Interferometry Satellite Aperture Radar ground motion imaging. We will also conduct groundwater chemistry and isotope surveys at the target sites, in order to identify temporal variations related to fluid injection with a focus on potential earthquake precursory signals. Field observations will be used to constrain the poroelastic model for simulating fluid pressure and solid matrix stress changes due to injection, and for designing injection strategies that reduce the likelihood of triggered seismic slip on pre-existing faults. The outcome of this project will provide unbiased scientific knowledge for the public policy making by our supporting organization GSC as well as regulatory policy adjustment by provincial oil and gas commissions.