CAREER: Induced seismicity: Increasing understanding of fluids in fault zones and engaging stakeholders for rapid knowledge transfer

近年来，美国境内发生在石油和天然气生产井附近的地震数量和公众关注度大幅上升。这些地震可能是由流体注入或抽出引起的地下岩层压力变化引发的，被称为诱发地震活动。这些地震对当地居民造成危害，并给能源生产带来挑战。然而，尽管最近进行了研究，我们仍然无法确定在注入之前，特定区域的井是否可能引发地震，如果会引发地震，数量和震级是多少。本研究旨在确定控制诱发地震活动的主要因素，测试沿地下断层带检测增加的流体压力的地震方法，这可能会增加地震风险，并研究中度地震期间断层滑动过程中断层是否产生可检测的地震信号。这项研究的结果将与相关研究相结合，为当地居民、石油和天然气监管机构、石油和天然气公司或为这些团体提供咨询的科学家等利益相关者提供有关诱发地震活动的最新且公正的科学信息。由于诱发地震活动的发生与废水处理井、水力压裂作业、地热刺激、天然气生产和天然气储存有关，因此这些结果将对能源资源开发具有广泛的全球意义。诱发地震活动是地下长期碳储存的潜在挑战，而地下碳储存是消除大气中二氧化碳从而减轻气候变化影响的主要解决方案之一。这项研究的结果还可以深入了解地震期间断层滑动启动的过程。这项研究将使用长期和密集的被动地震网络获取地震数据，其中包括已知大断层附近的大量废水处理区域。数据将用于监测远离活动井的压力传播的地震或抗震性质，并探测局部断层的地震响应性。 45 个宽带地震仪将在为期 18 个月的两次部署中以约 5 公里的间隔部署，首先在俄克拉荷马州，随后在主动流体注入的补充区域。在首次部署的空间范围内，将在活跃变化的地震活动上部署高密度阵列。具体来说，该研究将解决：1）密集阵列是否能够通过检测流体压力迁移信号来连续绘制远离废水处理井的压力迁移前沿； 2）这种迁移沿着断层/裂缝的狭窄路径集中或分散在多个路径上的程度； 3）大断层带是否对附近较大的地震有地震反应； 4）震源特征是否随着流体压力的增加而随时间变化。俄克拉荷马州中北部地区有活跃的地震活动、大型处置井和主要断层系统。在第二个地区，地质环境截然不同，这项研究将测试和完善检测接近断层的高流体压力信号的方法。两次部署的结果将在全球诱发地震活动的背景下进行综合。这项研究旨在吸引当地居民参与，帮助他们更有信心找到必要的信息，从而做出对他们的生活至关重要的明智决策。科学结果将在其他团体完成的研究的经常更新综合的背景下传达给利益相关者。这项工作将吸引地球科学和工程灾害和资源领域的下一代领导者参与。

Earthquakes occurring near oil and gas production wells have surged in number and public visibility within the US in recent years. These earthquakes may be triggered by pressure changes in subsurface rock layers resulting from injection or withdrawal of fluids, and are referred to as induced seismicity. These earthquakes pose a hazard to local residents and create challenges for energy production. However, despite recent research, we remain unable to determine, prior to injection, whether wells in a given area are likely to induce earthquakes, and if so, of what number and magnitude. This research seeks to determine the primary factor(s) controlling the triggering of induced seismicity, to test seismic methods of detection of increased fluid pressure along subsurface fault zones that may potentially increase seismic risk, and to investigate whether faults produce detectable seismic signals during the initiation of fault slip during moderate earthquakes. Results from this research will be combined with related studies to provide current and unbiased scientific information regarding induced seismicity to stakeholders, such as local residents, oil and gas regulators, oil and gas corporations, or scientists advising these groups. The results will have broad global significance for energy resource development since induced seismicity has occurred in association with wastewater disposal wells, hydraulic fracturing operations, geothermal stimulation, gas production, and gas storage. Induced seismicity is a potential challenge for long-term carbon storage in the subsurface, one of the primary solutions proposed to remove carbon dioxide from the atmosphere, thus mitigating the impacts of climate change. Results from this research may also provide insight into the processes by which fault slip initiates during earthquakes.This research will acquire seismic data using long-term and dense passive seismic networks, encompassing regions of high-volume wastewater disposal near known large faults. Data will be used to monitor the seismic or aseismic nature of pressure propagation away from active wells, and to probe the seismic responsiveness of the local faults. Forty-five broadband seismometers will be deployed at about 5 km spacing in two 18-month deployments, first in Oklahoma and subsequently in a complementary region of active fluid injection. Within the spatial footprint of the first deployment, a high-density array will be deployed over actively evolving seismicity. Specifically, the research will address 1) whether dense arrays are capable of continuously mapping pressure migration fronts away from wastewater disposal wells by detecting signals from fluid pressure migration; 2) the degree to which this migration is focused along a narrow pathway of faults/fractures, or dispersed over multiple pathways; 3) whether large fault zones are seismically reactive to the larger nearby earthquakes; and 4) whether seismic source characteristics change temporally as fluid pressure increases. The region within north-central Oklahoma includes active seismicity, large disposal wells, and a major fault system. In the second region, with a contrasting geological environment, this research will test and refine methods to detect signals of high fluid pressure approaching faults. Results from both deployments will be synthesized in the global context of induced seismicity. This research seeks to engage local residents and to help them become more confident in finding the information necessary to make informed decisions important in their lives. The scientific results will be communicated to stakeholders, within the context of a frequently updated synthesis of research completed by other groups. This work will engage next-generation leaders in the fields of hazards and resources across geoscience and engineering.