基于扩频原理的井下液位连续测量方法研究

【作者】 阎蕊；

【导师】 李斌；

【作者基本信息】 西北工业大学 ， 通信与信息系统， 2004， 硕士

【摘要】 在油井开采过程中，需要对油井的温度、压力、液位等参数进行测量，以监控采油过程。其中液位是一个很重要的参数。 目前正在应用的井下液位测量仪器，主要是通过爆炸声源产生大功率声脉冲信号，利用微音器接收回波信号，人为地对回波信号曲线进行分析来估算液位。传统方法中，由于人为因素的影响，测量结果的误差较大，而且不直接，不方便，无法自动完成测量，同时，爆炸声源的使用引入了火工品，存在一定的安全隐患。因此，亟待探索一种安全、方便、精确测量液位的方法。本文提出了一种新的基于扩频通信原理的液位测量方法，使用可控声源，发射较低功率的频谱扩展信号，在接收端对回波信号进行匹配滤波处理，通过检测相关峰来确定特征回波的位置，从而计算出液位。此外，本方法在传统测量方法的基础上，结合了计算机技术，整个过程可靠迅速，克服了常规方法由于人工判读所带来的误差和操作不便等缺点，可极大地提高液位测量的自动化程度和结果的测量精度。 本文首先介绍了超声测距的基本原理，分析了信道的声传输特性；接着将传统液位测量方法和新型液位测量方法的系统构成和信号分析处理方法做比较；然后对系统的发射信号(直接序列扩频信号和线性调频信号)的特点进行了研究，并着重讨论了回波信号的相关处理；最后对水管模拟实验测量结果和油田实地测量结果分别进行了分析和讨论。更多还原

【Abstract】 The operation of an oil well requires the measurement of temperature, pressure and the fluid level. Those parameters are used to monitor and control the operation of the oil well. And the fluid level is a very important parameter.Most present acoustic level gauges use a sound generator which can produce high-power acoustic waves and a microphone which can detect the echo signal. The fluid level can be worked out based on the artificial analysis of the echo curve. In this way, the influence of artificial disturbing in the measurement is unavoidable and the result is not very accurate and can not be measured automatically and directly, furthermore, there are some unsafe elements for the use of gun powder which is used to generate a high-power acoustic signal. Searching a new method to measure the fluid level accurately, safely and directly becomes important. A new fluid level measurement method, based on ultrasonic measurement, for calculating the velocity of sound and the fluid level is presented. This method points out that a low-power acoustic signal generator under control can be used to emit spread spectrum signals and the fluid level can be worked out by detecting the correlation-peak output of the matching filter whose input is the echo signal received by a microphone. The method, utilizing computer technique, removes the influence of artificial reading & calculating, makes the measurement accurate, easy, direct and safe.This thesis firstly introduces the method of ultrasonic measurement and analyzes the properties of the acoustic channel. In the second part,the new method is compared with the old one in such aspects as system structure and signal processing methods. In the third part, the properties of DSSS and LFM systems, especially the echo signal correlation processing of the systems are discussed. The last part are the respective analyses of water-pipe simulation experiment results and the trial results in Zhong Yuan oil field.更多还原