MRI: Acquisition of a fiber optic distributed acoustic sensing instrument for hydrological and seismological research

MRI：购买用于水文和地震研究的光纤分布式声学传感仪器

基本信息

批准号：
1920334
负责人：
Matthew Becker
金额：
$ 31.04万
依托单位：
California State University-Long Beach Foundation
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-08-15 至 2021-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1920334&HistoricalAwards=false
关键词：
MRI Acquisition fiber optic distributed

项目摘要

The earth deforms constantly in response to fluid pressure, the movement of tectonic plates, and the gravitational pull of the moon and sun. The shallow expression of this deformation, or strain, has important implications. For example, strain in geologic material due to changes in subsurface fluid pressure must be considered in the sustainability of groundwater, the extraction of hydrocarbons, and the efficiency of geothermal well fields. Tectonic forces cause measurable strain that ultimately result in earthquakes. Ground deformation must be considered in the design of buildings and roads. The natural pull of the moon and sun cause earth tides which have little direct effect on humans, but can be used to characterize the mechanical properties of earth materials. A challenge in measuring earth deformation, however, is that while strain is distributed over large distances, typical measurement devices such as strain meters measure only over short intervals. For this project, a sensing system is developed that can measure distributed strain at sub-meter intervals over the distance of kilometers. Although the instrument is available commercially, this application is entirely new and will reveal deformation not previously observed in the shallow subsurface. It has been adopted rapidly by the petroleum and security industries but is largely unknown in academia due to the high cost of contracting service companies. This MRI acquisition is intended to bring this next-generation commercial technology into the hands of academic researchers and students so it can be used to advance the understanding of earth movements in both natural and engineered earth systems. A consortium of California State University Long Beach, California Institute of Technology, and University of Southern California will share the instrument. This consortium will be led by a California State University Long Beach, which is a non-PhD granting and Hispanic Serving university with about half the population considered NSF Underrepresented minority (URM) students. The other two members, California Institute of Technology and University of Southern California are top PhD-granting institutions. Sharing of the instrument and training will expose URM students to research cultures and experiences to which they would not normally have access. A two-day DAS-training workshop will provide researchers and students outside of the consortium and opportunity to learn about DAS technology. The MRI program will provide URM students the opportunity to be among the first students in the country to have hands-on experience with DAS imaging.This Major Research Instrumentation (MRI) acquisition of a Fiber Optic Distributed Acoustic Sensing (DAS) will support measurement of ground motion related to tectonic and hydraulic forcing. DAS is a transformative technology for measuring strain and vibration in Earth environments. Using laser interferometry, dynamic strain is interrogated along the entire length of a fiber optic cable. DAS typically has sampling resolution of 1 kHz every 25 cm along a fiber optic cable that can be tens of kilometers in length. This technology allows the measurement of seismic movements along communication networks and in deep boreholes, often along fiber-optic cable that is already present. The system measures strain on a fiber-optic cable that can be installed, for instance, in deep boreholes or in shallow trenches. Strains of less than 1 nanometer (one billionth of a meter) per meter can be detected. The technology behind it is called distributed acoustic sensing (DAS) and was developed for measuring vibration in response to sound or seismic waves. The advancement here is that strain is measured over periods approaching a day, while vibrations are usually measured at periods of less than a second. A particular focus of research will be extension of frequency resolution into the microHertz range, where tidal forcing and ultra-low-frequency ground motions can be observed.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

地球不断响应流体压力，构造板的运动以及月球和太阳的引力。这种变形或应变的浅表达具有重要的含义。例如，必须考虑地下水压力变化而导致的地质材料的应变，地下水的可持续性，提取碳氢化合物的提取以及地热井田的效率。构造力导致可测量的应变最终导致地震。在建筑物和道路的设计中必须考虑地面变形。月亮和太阳的自然拉力引起的土潮对人类几乎没有直接影响，但可用于表征地球材料的机械性能。但是，测量地球变形的一个挑战是，尽管应变分布在大距离上，但典型的测量设备（例如应变仪表）仅在短时间内测量。对于该项目，开发了一个传感系统，可以在公里距离内以次级间隔测量分布式应变。尽管该仪器在商业上可用，但此应用程序是全新的，并且会揭示以前在浅层地下中观察到的变形。它已被石油和安全行业迅速采用，但由于承包服务公司的成本很高，因此在学术界基本上未知。这种MRI获取旨在将这项下一代商业技术带入学术研究人员和学生的手中，因此可以用来促进对天然和工程地球系统中地球运动的理解。加利福尼亚州长海滩的加利福尼亚州立大学一国联盟和南加州大学将共享该工具。该财团将由加利福尼亚州立大学长滩领导，这是一个非phd授予和西班牙裔服务大学，大约一半的人口被认为是NSF代表性不足的少数民族（URM）学生。另外两名成员，加利福尼亚理工大学和南加州大学是博士学位授予机构的顶级机构。分享仪器和培训将使URM学生接触他们通常无法获得的文化和经验。为期两天的DAS培训研讨会将为财团以外的研究人员和学生提供了解DAS技术的机会。 MRI计划将为URM学生提供机会成为该国最早具有DAS成像经验的学生之一。这项主要的研究仪器（MRI）获取光纤分布式声学传感（DAS）将支持测量与构造和液压强迫有关的地面运动。 DAS是一种用于测量地球环境中应变和振动的变革性技术。使用激光干涉法，沿着光纤电缆的整个长度询问动态应变。 DAS通常沿光纤电缆每25厘米的采样分辨率为1 kHz，长度为数十公里。这项技术允许沿通信网络和深钻孔进行地震运动的测量，通常沿已经存在的光纤电缆。该系统测量可以安装的光纤电缆上的应变，例如，在深钻孔或浅沟渠中。可以检测到小于1纳米（十亿分之一米）的菌株每米。其背后的技术称为分布式声感应（DAS），并开发用于测量声音或地震波的振动。这里的进步是，应菌株在一天接近一天的时期内测量，而振动通常在小于一秒钟的时间内测量。研究的一个特殊重点将是将频率分辨率扩展到Microhertz范围，可以观察到潮汐强迫和超低频地面动作。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛影响的审查标准来通过评估来支持的。