光纤Bragg光栅在油气工业中的若干应用及进展

简要介绍光纤Bragg光栅的基本原理、传感检测系统的构成，以及利用光纤Bragg光栅进行温度、应变同时测量区分技术.光纤光栅作为新一代传感元器件，越来越受到广大油气工业用户的青睐.本文主要讨论光纤Bragg光栅在油气工业中的若干应用，并对存在问题和应用前景进行了展望.     

光纤布拉格光栅地震检波器的研究与应用

光纤布拉格光栅地震检波技术是一门较新的地震检波技术.实验表明,用光纤Bragg光栅做成的检波器不仅频带宽、稳定性好,而且灵敏度高,是一种较理想的地震勘探仪器.文章主要介绍了光纤布拉格光栅地震检波器的传感原理、理论计算及其工作原理,为光纤Bragg光栅地震检波器的研究以及实际应用提供了依据.     

油气井永久性光纤传感器的应用及其进展

论述了光纤传感器在油气藏永久监测中的应用及其进展,对分布式光纤温度传感器、基于干涉仪原理的光纤压力传感器以及多功能的光纤Bragg光栅传感器系统作了详细讨论．通过两个实例,来说明分布式温度光纤传感器系统(DTS)可以在井下解决的若干问题．最后,对光线传感器在油气生产及动态监测应用中存在的问题及发展趋势进行了讨论。     

一种光纤传感式油气探测地震检波器探头

高灵敏度波动和振动传感器是目前油气探测急需的关键技术之一.本文设计了一种光纤Bragg光栅(FBG)型波动和振动传感探头,分析了其工作参数和传感优势,给出了这种新型地震检波器探头结构的有限元分析结果和实验室振动测试结果.结果表明,这种检波器探头有较好的频率响应,测试性能稳定,此结构具有很高的灵敏度放大作用.     

光栅Bragg地震检波器的传感特性研究(英文)

针对目前石油地震勘探的瓶颈—检波器性能差的问题,设计了一种新型光纤Bragg光栅（FBG）地震检波器,阐述了其工作原理,并从理论上给出了检波器的响应函数等参数。由于FBG的传感优势,这种新型地震检波器动态范围可达94dB,灵敏度高,重量轻,造价低,是理想的新一代地震勘探信号采集单元。     

基于ARM的光纤Bragg光栅地震观测系统的研究

为满足地震观测系统对实时性、高精度以及网络化的要求,提出了基于光纤Bragg光栅传感器和ARM的嵌入式系统设计方案,阐述了可调光纤F-P滤波器的工作机理和特点,并介绍了基于FBG传感器和ARM的地震观测系统的硬件结构和软件设计.采用三星公司的S3C2440对经过可调谐F-P腔解调后的波长信息进行采集,并对得到的数据进行处理.实验结果表明,该系统在处理精度和实时性方面都能达到要求,性价比高,有一定实用价值.     

分布式光纤传感器原理及在地震监测中的应用研究现状

一般情况下,地震发生前都会出现各种异常信号,重点监测这些地震前兆信号对研究地震有重要意义.基于分布式光纤传感的地震监测应用系统,由于其自身的独特优势,在地震勘探领域正得到越来越广泛的重视,是目前理论界和实际应用的研究热点.DAS系统的基本原理是基于光纤的弹光效应,通过探测由弹光效应产生的光信号的相位、波长等参量,可以实...     

基于分布式光纤传感的堤坝安全监测技术及展望

及时、准确地掌握堤坝的性态，是保证堤坝安全运行的基础.因此，需要一种实时监测系统对堤坝进行监测.分析了堤坝健康监测的主要内容，介绍了分布式光纤传感技术的工作原理及使用现状；探讨了分布式光纤传感技术在我国堤坝渗流和形变中的应用；指出了分布式光纤传感技术在土堤坝使用中存在的问题，并给出了新的堤坝长期安全监测系统设计建议，结论有益于指导构建新的基于分布式光纤技术的堤坝安全监测系统.     

光纤振动传感之二:基于散射或透射光的本征传感及其地震学应用

本征光纤振动传感通过在光纤一端重复发射探测激光,在光纤同端或另外一端接收散射光或透射光并解调它们的变化,测量光纤上的动态应变(即振动).本征传感以光纤为传感器,具有结构简单,布设灵活,运维方便的优点,能应用于流体、高温、高压或强电磁干扰等恶劣环境,可以大幅度延伸可监测的区域,并实现相对廉价的长期连续监测.此外,光纤传感...     

基于拉曼散射的深孔测温技术研究

孔中测温作为一种原位测试方法,是地热资源勘察、开发中重要的研究内容.分布式光纤传感测温技术,能够弥补传统点式测温耗时与漏测的不足,同时传感光纤具有耐高温、高压和抗(钻井液)腐蚀性等特点,可实现钻孔恶劣环境下的分布式温度测量.本文利用拉曼散射和光时域反射技术,设计了深井分布式光纤温度测试系统.该系统采用波分复用技术,将后向拉曼散射光中的斯托克斯光与反斯托克斯光分离,利用反斯托克斯光的温度敏感特性感知环境温度,结合同源斯托克斯光,解调温度信息;根据光纤中光的传输速率和背向拉曼散射光的回波时间,可以对温度点进行定位,实现对光纤温度场的分布式测量.通过多点数字累加平均技术的微弱信号处理方法,并引入光纤突变损耗修正系数、光电采集影响系数等,借助光纤环基准参考,实现测温数据的解算.同时本文设计的深孔耐高温铠装测试光缆,可实现-65~350℃范围内的温度测试;结合GH_DR2号地热孔野外测试实验,完成测深800m,孔内最高温度54.8℃,证明此种测温方法的有效性和潜在的推广价值.     

Recent advances in earthquake monitoring I: Ongoing revolution of seismic instrumentation

Seismic networks have significantly improved in the last decade in terms of coverage density, data quality, and instrumental diversity. Moreover, revolutionary advances in ultra-dense seismic instruments, such as nodes and fiber-optic sensing technologies, have recently provided unprecedented high-resolution data for regional and local earthquake monitoring. Nodal arrays have characteristics such as easy installation and flexible apertures, but are limited in power efficiency and data storage and thus most suitable as temporary networks. Fiber-optic sensing techniques, inclu-ding distributed acoustic sensing, can be operated in real time with an in-house power supply and connected data storage, thereby exhibiting the potential of becoming next-generation permanent networks. Fiber-optic sensing techniques offer a powerful way of filling the observation gap particularly in submarine environments. Despite these technological advancements, various challenges remain. First, the data characteristics of fiber-optic sensing are still unclear. Second, it is challenging to construct software infrastructures to store, transfer, visualize, and process large amount of seismic data. Finally, innovative detection methods are required to exploit the potential of numerous channels. With improved knowledge about data characteristics, enhanced software infrastructures, and suitable data processing techniques, these innovations in seismic instrumentation could profoundly impact observational seismology.     

Wireless technologies for the monitoring of strategic civil infrastructures: an ambient vibration test on the Fatih Sultan Mehmet Suspension Bridge in Istanbul, Turkey

Rapid improvements in telemetry technology and the general decrease in communication costs have raised a growing interest in low-cost wireless sensing units. This is especially the case for structural monitoring purposes, where they are becoming a more valuable alternative to conventional wired monitoring system. The main advantages associated with the use of wireless sensing unit include a considerable decrease in installation costs, decentralization of data analysis, and the possibility of broadening the functional capabilities by exploiting the use, at the same time and place, of different sensors. In this work, the design of a low-cost wireless sensing unit able both to collect, analyze, store, and communicate data and estimated parameters is presented. The suitability of a network of these low-cost wireless instruments for monitoring the vibration characteristics and dynamic properties of strategic civil infrastructures is validated during a ambient vibration recording field test on the Fatih Sultan Mehmet Bridge in Istanbul, Turkey.     

Design, Installation, and Uses of Combination Ground Water and Gas Sampling Wells

Waste disposal sites with volatile organic compounds (VOCs) frequently contain contaminants that are present in both the ground water and vadose zone. Vertical sampling is useful where transport of VOCs in the vadose zone may effect ground water and where steep vertical gradients in chemical concentrations are anticipated. Designs for combination ground water and gas sampling wells place the tubing inside the casing with the sample port penetrating the casing for sampling. This physically interferes with pump or sampler placement. This paper describes a well design that combines a ground water well with gas sampling ports by attaching the gas sampling tubing and ports to the exterior of the casing. Placement of the tubing on the exterior of the casing allows exact definition of gas port depth, reduces physical interference between the various monitoring equipment, and allows simultaneous remediation and monitoring in a single well. The usefulness and versatility of this design was demonstrated at the Idaho National Engineering and Environmental Laboratory (INEEL) with the installation of seven wells with 53 gas ports, in a geologic formation consisting of deep basalt with sedimentary interbeds at depths from 7.2 to 178 m below land surface. The INEEL combination well design is easy to construct, install, and operate.     

Using slowness and azimuth fluctuations as new observables for four‐dimensional reservoir seismic monitoring

Four‐dimensional imaging using geophysical data is of increasing interest in the oil and gas industries. While travel‐time and amplitude variations are commonly used to monitor reservoir properties at depth, their interpretation can suffer from a lack of information to decipher the parts played by different parameters. In this context, this study focuses on the slowness and azimuth angle measured at the surface using source and receiver arrays as complementary observables. In the first step, array processing techniques are used to extract both azimuth and incidence angles at the source side (departure angles) and at the receiver side (arrival angles). In the second step, the slowness and angle variations are monitored in a laboratory environment. These new observables are compared with traditional arrival‐time variations when the propagation medium is subject to temperature fluctuations. Finally, field data from a heavy‐oil permanent reservoir monitoring system installed onshore and facing steam injection and temperature variations are investigated. The slowness variations are computed over a period of 152 days. In agreement with Fermat's principle, strong correlations between the slowness and arrival‐time variations are highlighted, as well as good consistency with other techniques and field pressure measurements. Although the temporal variations of slowness and arrival time show the same features, there are still differences that can be considered for further characterization of the physical changes at depth.     

Surveying earth resources by remote sensing from satellites

This paper reviews the techniques and recent results of orbital remote sensing, with emphasis on Landsat and Skylab imagery. Landsat (formerly ERTS) uses electronic sensors (scanners and television) for repetitive observations with moderate ground resolution. The Skylab flights used a wider range of electro-optical sensors and returned film cameras with moderate and high ground resolution. Data from these programs have been used successfully in many fields. For mineral resources, satellite observations have proven valuable in geologic mapping and in exploration for metal, oil, and gas deposits, generally as a guide for other (conventional) techniques. Water resource monitoring with satellite data has included hydrologic mapping, soil moisture studies, and snow surveys. Marine resources have been studied, with applications in the fishing industry and in ocean transportation. Agricultural applications, benefiting from the repetitive coverage possible with satellites, have been especially promising. Crop inventories are being conducted, as well as inventories of timber and rangeland. Overgrazing has been monitored in several areas. Finally, environmental quality has also proven susceptible to orbital remote sensing; several types of water pollution have been successfully monitored. The effects of mining and other activities on the land can also be studied. The future of orbital remote sensing in global monitoring of the Earth's resources seems assured. However, efforts to extend spectral range, increase resolution, and solve cloud-cover problems must be continued. Broad applications of computer analysis techniques are vital to handle the immense amount of information produced by satellite sensors.Abbreviations SSRERTS Symposium on Significant Results Obtained from the Earth Resources Technology Satellite - TERTSS Third Earth Resources Technology Satellite-1 Symposium National Academy of Sciences-National Research Council Research Associate at NASA Goddard Space Flight Center, 1974/75.Goddard Space Flight Center     

Aquifer Characterization Using Fiber Bragg Grating Multi-Level Monitoring System

Groundwater responses measured from multiple wells at different depths are essential for delineating the aquifer heterogeneity using hydraulic tomography (HT). In general, conducting HT requires many wells because traditional well monitoring is usually partially open at a specific depth interval or is fully penetrating. Accordingly, conducting an HT survey is typically costly and time-consuming. To tackle these issues, a new multi-level monitoring system (MLMS) for the HT survey was developed using the fiber Bragg grating (FBG) technique. This FBG MLMS could collect the depth-discrete groundwater observations from a fully penetrated 2-inch well. Three field campaigns were conducted to validate the capability of the FBG MLMS for HT surveys. The results show that the accuracy and stability of this MLMS are reliable and that FBG MLMS is beneficial for conducting an HT survey. Specifically, compared to the traditional monitoring well in an injection event, this FBG MLMS can concurrently cause an increase in the number of cross-hole tests several times and collect many more head observations than the standard methods, resulting in the observed flow fields efficiently reaching ergodic conditions and effectively improving the accuracy of the estimated hydraulic heterogeneity. Therefore, the FBG MLMS could be an alternative MLMS for efficiently and economically conducting an HT survey.     

Long-Term Confidence in Ground Water Monitoring Systems

State-of-the-art analytical techniques are capable of detecting contamination In the part per billion (ppb) range or lower. At these levels, a truly representative ground water sample Is essential to precisely evaluate ground water quality. The design specifications of a ground water monitoring system are critical in ensuring the collection of representative samples, particularly throughout the long-term monitoring period.
The potential interfaces from commonly used synthetic well casings require a thorough assessment of site, hydrogeology and the geochemical properties of ground water. Once designed, the monitoring system must be installed following guidelines that ensure adequate seals to prevent contaminant migration during the installation process or at some time in the future. Additionally, maintaining the system so the wells are in hydraulic connection with the monitored zone as well as periodically Inspecting the physical integrity of the system can prolong the usefulness of the wells for ground water quality. When ground water quality data become suspect due to potential interferences from existing monitoring wells, an appropriate abandonment technique must be employed to adequately remove or destroy the well while completely sealing the borehole.
The results of an inspection of a monitoring system comprised of six 4-inch diameter PVC monitoring wells at a hazardous well facility Indicated that the wells were improperly installed and in some cases provided a pathway for contamination. Subsequent down hole television inspections confirmed inaccuracies between construction logs and the existing system as well as identified defects in casing materials. An abandonment program was designed which destroyed the well casings in place while simultaneously providing a competent seal of the re-drilled borehole.     

Renovated controller designed by genetic algorithms

A novel smart control system based on genetic algorithms (GAs) is proposed in this paper. The system is comprised of three parts: the fiber Bragg grating (FBG) sensor‐based sensing network for structural health monitoring, the GA‐based location optimizer for sensor arrangement, and the GA‐based controller for vibration mitigation under external excitation. To evaluate the performance of the proposed system, an eight‐story steel structure was designed specifically to represent a structure with large degrees of freedom. In total 16 FBG sensors were deployed on the structure to implement the concept of a reliable sensing network, and to allow the structure to be monitored precisely under any loading. The advantage of applying a large amount of information from the sensing system is proven theoretically by the GA‐based location optimizer. This result greatly supports the recent tendency of distributing sensors around the structure. Two intuitive GA‐based controllers are then proposed and demonstrated numerically. It is shown that the structure can be controlled more effectively by the proposed GA‐strain controller than by the GA‐acceleration controller, which represents the traditional control method. A shaking table test was carried out to examine the entire system. Experimental verification has demonstrated the feasibility of using this system in practice. Copyright © 2008 John Wiley & Sons, Ltd.     

The Italian strong motion network

The Italian Strong Motion Network is a permanent monitoring system run by the Italian national emergency management department (Dipartimento della Protezione Civile, DPC). The network is known as RAN (Rete Accelerometrica Nazionale). An extensive project for updating and improving the technology of RAN instruments as well as the number of recording points was performed in the last 10 years. A wide site selection survey was carried out from eastern Sicily along the Italian peninsula, covering high seismic risk areas. The recording station density and the choice of high-quality digital strong motion instruments ensure reliability of the RAN network in the long-term. At the end of 2008, the free field sites selection and instruments installation, planned in the project, were quite completed. In planning and drawing the new RAN, special attention has been devoted to the robustness of the transmission systems, and to the distribution of new stations in order to ensure plenty of data during a seismic emergency. We spent special care both in the estimation of the RAN site responses and in the diffusion of the strong motion data. In order to better identify damaged earthquake areas, improved ground motion parameters need to be set. Such parameters will also assist future progress for engineering seismic design techniques as well as disaster mitigation.