摘要
随着全球对天然气的大量需求，天然气的消耗不断的加快，中国作为一个人口大国对天然气的需求更加迫切，但由于地区差异，大部分的天然气能源储存在西部，而我国的主要人口在东部，因此提出了“西气东输”的政策。盐穴型储气库因其储存量大，占地面积小，安全系数高，运行速率快且对生态环境影响小等优点，被广泛的应用于天然气储存。通过钻井技术钻穿盐岩层，再注入淡水进行冲蚀，抽出卤水后形成的溶腔，从而实现对气体的储存。为了保证盐穴储存库的稳定，在造腔的过程中，必须对其进行实时监测，保证溶解盐岩后形成的腔体形态符合设计要求。利用超声测距技术测量盐穴腔体的半径，改变超声波探头的位置，得到不同深度腔体的半径及水平剖面图，为后期的造腔提供方向性指导。
针对盐穴储气库的稳定性检测，建立了一个盐腔三维形态超声检测系统，对造腔过程中的腔体形态进行监测，以便于调整造腔的工艺，提高盐穴造腔的稳定性。根据超声波的性质，对超声信号进行数字滤波处理和小波阈值去噪，实验表明超声信号通过数字滤波去噪后信噪比、抗干扰能力、测量精度和准确度都远低于小波阈值去噪。本文还研究超声测距的几种时延估计算法，利用超声测距系统测量数据分析了传统阈值法、互相关法和包络峰值法。在超声测距时的这几种方法的抗干扰能力较弱，受幅值影响较大，测量的精度、准确性和稳定性不高；因此提出了一种改进的相关包络的测距方法。实验表明改进的超声信号处理方法不仅可以确定唯一包络峰值的位置，而且提高了测量精度，还不易受噪声影响，测量结果稳定，系统测量误差也更小。
检测盐穴腔体形态所采集到的信号是非线性、非平稳超声回波信号，一般采用时频分析方法进行处理，本文研究了几种典型的时频分析方法：短时傅立叶变换，小波变换，魏格纳-威利分布和希尔伯特黄变换。对比分析这四种时频分析方法，并选择希尔伯特黄变换作为本系统的超声信号时频处理方法。通过该方法对回波信号进行特征提取，得到希尔伯特黄的时频谱图；分析超声信号的频率随时间变化的情况，并根据时间轴上信号频谱的变化，找到对应超声发射频率的时间点；最后通过超声测距的距离公式得到盐穴腔体的半径以及这个腔体的形态信息，进而分析当前的腔体形态的稳定性。
关键词：地下储气库，盐穴造腔，超声信号，超声测距，时延估计算法，时频分析
Abstract
With the huge demand for natural gas in the world,the consumption of natural gas is accelerating,and the demand for natural gas in China,a populous country,is more urgent.However,due to regional differences,most of the natural gas energy is stored in the west,while China's main population is in the east.Therefore,China has put forward the policy of"west-east gas transmission".Salt cavern gas storage is widely ud in natural gas storage due to its advantages of large storage capacity, small occupation area,high safety factor,fast operation rate and small impact on the ecological environment.Salt cavern storage is to drill through the salt rock layer by drilling tec
hnology,and then through the injection of fresh water for erosion,brine after the formation of dissolved cavity,gas storage.In order to ensure the stability of salt cavern storage,the cavity must be monitored in real time in the process of cavity building to ensure that the cavity form formed after dissolving salt rock meets the design requirements.The ultrasonic ranging technique was ud to measure the radius of the salt cavity,and the horizontal profile and radius of the cavity with different depths were obtained by changing the position of the ultrasonic probe, which provided directional guidance for the cavity construction in the later stage.
In this paper,a three-dimensional ultrasonic detection system of salt cavity shape was established for the stability detection of salt cavity gas storage rervoir, and the cavity shape was monitored during the cavity building process,so as to adjust the cavity building process and improve the stability of salt cavity building.Firstly, according to the nature of ultrasonic wave,the denoising effect of ultrasonic echo signal after digital filtering processing and wavelet threshold processing is compared. The experiment shows that the signal-to-noi ratio,anti-interference ability, measurement accuracy and accuracy of ultrasonic echo signal after digital filtering denoising are far lower than that of wavelet threshold denoising.In this paper,veral delay estimation algorithms of ultrasonic ranging are also studied.The traditional threshold method,cross-correlation method and envelope peak method are a扬鞭奋蹄
nalyzed by using the measurement data of ultrasonic ranging system.Then an improved correlation envelope ranging method is propod.The experimental results show that the anti-noi capability of the improved ultrasonic signal processing method is obviously better than the previous methods,and the measurement of ultrasonic transmission time is only related to the position of the envelope peak.Compared with the traditional ultrasonic signal processing method,this method can not only determine the location of the unique envelope peak,but also improve the measurement accuracy,and is not easily affected by noi,the measurement result is stable,and the system measurement error is smaller.
The signals collected by detecting the radius of salt cavity are nonlinear and non-stationary ultrasonic echo signals,which are generally procesd by time-frequency analysis method.Therefore,veral typical time-frequency analysis
龙华渔村
methods are studied in this paper:short-time Fourier transform,wavelet transform, Wigner-Ville distribution and Hilbert yellow transform.The four time-frequency analysis methods are compared and the Hilbert yellow transform is lected as the time-frequency processing method of the ultrasonic signal.The time spectrum of Hilbert yellow is obtained by feature extraction of echo signal.The change of frequency of ultrasonic signal with time is analyzed,and the corresponding time
point of ultrasonic transmitting frequency is found according to the change of signal spectrum on the time axis.Finally,the radius of the cavity and the shape information of the cavity are obtained by the distance formula of ultrasonic ranging,and then the stability of the current cavity shape is analyzed.
Keywords:underground gas storage,salt cave cavity,ultrasonic signal,ultrasonic, delay estimation algorithm,the time-frequency analysis马的简笔画
目录
第1章绪论 (1)
1.1研究背景 (1)
我想对您说作文400字1.2国内外研究现状 (3)
1.3研究内容 (5)
第2章超声波测距理论研究 (8)
2.1超声波的基本理论 (8)
2.2超声波测距原理 (9)爱的背后
2.3超声测距系统 (10)
2.4本章小结 (11)
第3章超声信号去噪和超声测距时延估计算法 (12)
3.1超声信号消噪方法 (12)
3.3超声测距的时延估计算法 (17)卡尔文森
3.3本章小结 (23)
第4章时频分析方法研究 (24)
4.1传统的时频分析方法 (24)
4.2希尔伯特黄变换 (30)
4.3本章小结 (38)
第5章Hilbert-Huang变换在盐腔形态测量上的应用 (39)
5.1盐穴腔体三维形态超声测量系统 (39)
5.2实验与仿真 (40)
5.3本章小结 (47)
遐迩一体第6章总结与展望 (48)
6.1主要研究工作及总结 (48)
6.2研究展望 (49)
致谢 (50)
个人简介 (51)
参考文献 (52)
第1章绪论
第1章绪论
1.1研究背景
中国人口众多，生活需求量大，天然气作为一种清洁能源，它的存储和高效利用，已经成为了中国多年来不断研究探索的课题。地下储气库具有储存量比较大、使用寿命较长、调峰的范围广、灵活性强且比地面设施安全性高等特点，因此我们一般使用该方式存储天然气[1]，其方法是把天然气田中的天然气采出并注入地下空间进行保存，从而形成人工气田[2]。地下储气库作为现如今最主要的天然气储存方式，在中国调峰和输送天然气方面发挥着的极其重要的作用。中国大部分的天然气资源都集中在西部地区，因此我国施行了“西气东输”的政策来保障社会发展的需求[3]。地下储气库的建造成本少、安全性高，已成为高消耗天然气国家储存天然气的重要方式。地下储气库是远距离天然气输送系统必不可少组成部分，通过地下储气库来保证天然气管道能够不间断的进行供气，如图1-1是地下储气库的气体输送[4]。
图1-1地下储气库气体输送
Fig.1-1Gas transport from underground gas storage facilities
经国内外学者不断的深入研究，现如今建造地下储气库的技术已经比较成熟的，它主要包含四种类型：盐穴、含水层、枯竭油气藏和矿坑等[5]。由于盐穴储气库安全性高、不易泄露、占地面积小、注采气灵活、运行效率高还不易受自然灾害的影响等优点，因此在保障天然气安全平稳运输方面起到了关键作用[6]。国内外学者对于盐岩的理论和力学性进行了大量的研究，为盐穴储气库的稳定性评价提
荷石水禽图
供有效的研究方法，从而在盐穴储气库的研究上取得重大的进步[7]。
