RAPID: Collaborative Research: Response to the 2016 M5.8 Pawnee Earthquake: Using MT to map Fluids in Faults

RAPID：协作研究：响应 2016 年 M5.8 波尼地震：使用 MT 绘制断层中的流体图

• 批准号: 1664474
• 负责人: Estella Atekwana
• 金额: $ 2.32万
• 依托单位: Oklahoma State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-11-01 至 2017-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1664474&HistoricalAwards=false
• 关键词: RAPID; Collaborative; Research; Response; 2016

Since 2008, there has been a dramatic increase in earthquake activity in the central United States in association with major oil and gas operations. Oklahoma is now considered one of the most seismically active states. Some of the earthquakes are occurring near populated cities and also in areas of high national security such as Cushing, Oklahoma, a major hub of the U.S. oil and gas pipeline transportation system. Unlike earthquakes in California and Alaska that can be clearly linked to deformation along plate boundaries, the cause of the earthquakes in Oklahoma remains a very contentious and highly debated topic. However, there is an increasing body of scientific evidence to suggest that the increased level of seismicity is linked to the injection of saline production wastewaters from drilling activity related to petroleum exploitation. Although seismic networks are able to detect activity and map its hypocenter, they are unable to image the distribution of fluids in the fault responsible for triggering seismicity. The magnetotelluric (MT) technique, uses naturally occurring electric and magnetic fields measured at Earth?s surface to measure conductivity structure. The 2016 M5.8 Pawnee, Oklahoma earthquake provides an unprecedented opportunity for scientists to provide a link between seismicity and imaging of fluids on or around faults. Thus we will carry out a series of two-dimensional (2D) profiles located through areas where the fault recently ruptured and seismic activity is concentrated and also across the faults in the vicinity that did not rupture. The integration of our results and ongoing seismic studies will lead to a better understanding of the links between fluid injection and seismicity. Results of this study can inform decisions by policy-makers. Electrical geophysical methods are ideally suited to image fluid bearing faults since the produced waters are highly saline and hence have a high electrical conductivity. To date, no study has imaged the fluids in the faults in Oklahoma and made a direct link to the seismicity. Several injection wells are located within a 20 km radius of the epicenter; and studies have suggested that injection of fluids in high-volume wells can trigger earthquakes as far away as 30 km. This proposal will collect MT geophysical data that will constrain the distribution of fluids in the fault zone that ruptured during the 2016 M5.8 Pawnee earthquake. Because most injection activities have been temporarily suspended following the September 3, 2016 earthquake, we have the unique opportunity to capture the state of the fluid induced seismicity process before the system is altered by additional wastewater injection. Given that seismicity in in Oklahoma has been met with public outcry, with demands for action by legislators. However, any decision by stakeholders and policy makers must be guided by sound science and unbiased data. Geologically informed approaches to characterizing induced seismicity for inclusion in seismic hazard evaluations is critical for evaluation of sensitive facilities. As a result, our proposed MT survey has multi-faceted broader impacts: (1) It will produce data-constrained results that will lead to a better understanding of migration of wastewater ? fault interactions. (2) We will produce relevant data that can be used to inform the decisions of policy-makers and stakeholders when assessing seismic hazards related to wastewater injection. (3) Our project will engage several students. Students will assist with the data acquisition and will gain hands-on experience from MT experts in how to deploy MT instrumentation. At least two of the students will come from under-represented groups, thereby building a diverse workforce in science and engineering

自2008年以来，美国中部与主要石油和天然气运营相关的地震活动急剧增加。现在，俄克拉荷马州被认为是最活跃的状态之一。一些地震发生在人口稠密的城市附近以及国家安全高的地区，例如库欣，俄克拉荷马州，这是美国石油和天然气管道运输系统的主要枢纽。与加利福尼亚和阿拉斯加的地震不同，可以与板块边界的变形明显联系在一起，俄克拉荷马州地震的原因仍然是一个非常有争议且高度争议的话题。但是，有越来越多的科学证据表明，地震性水平的提高与注射盐水产量的废水有关与石油剥削有关的钻井活动。尽管地震网络能够检测活动并绘制其降解器，但它们无法对负责触发地震性的断层中的流体分布进行成像。 磁铁（MT）技术使用在地球表面测得的自然存在的电场和磁场来测量电导率结构。 2016年M5.8波尼，俄克拉荷马州的地震为科学家提供了前所未有的机会，可以在断层或周围的流体成像之间提供联系。因此，我们将执行一系列二维（2D）轮廓，该区域位于最近破裂的区域，地震活动被集中，并且跨越附近的断层，而没有破裂。我们的结果和正在进行的地震研究的整合将使人们更好地理解流体注入与地震性之间的联系。 这项研究的结果可以为政策制定者的决定提供依据。电地球物理方法理想地适合于成像流体轴承断层，因为产生的水是高盐水，因此具有很高的电导率。迄今为止，尚无研究对俄克拉荷马州断层中的流体进行成像，并直接与地震性联系起来。几个注入井位于震中半径20 km之内。研究表明，在高体积井中注入液体可以触发地震远至30公里。该提案将收集MT地球物理数据，该数据将限制在2016 M5.8 Pawnee地震期间破裂的断层区域中流体的分布。由于大多数注射活动在2016年9月3日地震之后暂时暂停，因此我们有独特的机会在系统被额外的废水注入更改之前捕获流体诱导的地震性过程。鉴于俄克拉荷马州的地震性已受到公众的强烈抗议，并要求立法者采取行动。但是，利益相关者和政策制定者的任何决定都必须以合理的科学和公正的数据为指导。地质知情的方法是表征诱导的地震性以纳入地震危险评估，对于评估敏感设施至关重要。结果，我们提出的MT调查具有多方面的广泛影响：（1）它将产生受数据约束的结果，从而更好地了解废水的迁移？故障相互作用。 （2）在评估与废水注射相关的地震危害时，我们将产生相关数据，可用于告知决策者和利益相关者的决定。 （3）我们的项目将吸引几个学生。学生将协助数据获取，并将获得MT专家如何部署MT仪器的动手经验。至少有两个学生来自代表性不足的团体，从而在科学和工程领域建立了多样的劳动力