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.

地球因流体压力、板块运动以及月球和太阳的引力而不断变形。这种变形或应变的浅层表达具有重要意义。例如，在地下水的可持续性、碳氢化合物的提取以及地热井场的效率方面，必须考虑由于地下流体压力的变化而导致的地质材料应变。构造力会产生可测量的应变，最终导致地震。建筑物和道路的设计必须考虑地面变形。月球和太阳的自然引力引起的地球潮汐对人类影响不大，但可以用来表征地球材料的力学性能。然而，测量地球变形的一个挑战是，虽然应变分布在很长的距离上，但典型的测量设备（例如应变计）只能在很短的间隔内进行测量。对于该项目，开发了一种传感系统，可以测量公里距离内亚米间隔的分布应变。尽管该仪器已在商业上销售，但该应用是全新的，将揭示以前在浅层地下观察到的变形。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高昂，在学术界基本上不为人所知。此次 MRI 收购的目的是将这项下一代商业技术带到学术研究人员和学生的手中，以便它可以用来增进对自然和工程地球系统中地球运动的理解。加州州立大学长滩分校、加州理工学院和南加州大学组成的联盟将共享该仪器。该联盟将由加州州立大学长滩分校领导，该大学是一所不授予博士学位的西班牙裔服务大学，约有一半的人口被视为 NSF 代表性不足的少数族裔 (URM) 学生。另外两个成员加州理工学院和南加州大学都是顶尖的博士学位授予机构。共享仪器和培训将使 URM 学生接触到他们通常无法接触到的研究文化和经验。为期两天的 DAS 培训研讨会将为联盟之外的研究人员和学生提供了解 DAS 技术的机会。 MRI 项目将为 URM 学生提供成为该国第一批拥有 DAS 成像实践经验的学生的机会。光纤分布式声学传感 (DAS) 的这项重大研究仪器 (MRI) 收购将支持测量与构造和水力强迫有关的地面运动。 DAS 是一项用于测量地球环境中的应变和振动的变革性技术。使用激光干涉测量法，可以沿着光缆的整个长度询问动态应变。 DAS 通常在长达数十公里的光缆上每 25 厘米具有 1 kHz 的采样分辨率。该技术可以测量沿着通信网络和深井的地震运动，通常沿着已经存在的光纤电缆。该系统测量可安装在深钻孔或浅沟等地方的光缆应变。每米小于 1 纳米（十亿分之一米）的应变可以被检测到。其背后的技术称为分布式声学传感 (DAS)，旨在测量响应声波或地震波的振动。这里的进步在于，应变是在接近一天的时间内测量的，而振动通常是在小于一秒的时间内测量的。研究的一个特别重点是将频率分辨率扩展到微赫兹范围，在该范围内可以观察到潮汐强迫和超低频地面运动。该奖项反映了 NSF 的法定使命，并通过使用基金会的知识产权进行评估，被认为值得支持。优点和更广泛的影响审查标准。