【作者】 洪泓；

【导师】 田日才；

【作者基本信息】 哈尔滨工业大学 ， 信息与通信工程， 2009， 硕士

【摘要】 在石油开采行业中,为了解油井的产油能力,掌握生产动态,需要对油井内温度、压力和液位等参数进行日常的测量。其中油井液位测量是推算油层压力的大小、确定油井的生产能力以及选择油井最合理的生产方式的重要依据。目前油井液位测量主要是使用爆炸声源产生大功率的声脉冲信号打入井下,声波脉冲沿井管传播,遇到液面反射,由微音器接收回波信号。通过分析回波信号估计传播时延,进而推算出液面的深度。虽然可以通过各种滤波和相关处理方法可以提高信噪比,更好地识别接箍波和液面波,但是这种脉冲测距方法易受杂波干扰,测量精度和深度受到限制,同时安全性不高。为解决这些问题,本论文将扩频理论引入油井液位测量,利用低功率谱密度下声波扩频信号实现油井液位的精确测距。本文的主要研究内容包括:声学基本原理以及声波在管道中传播的特性;扩频基本原理特别是扩频测距的性能优势和m序列参数选择方法和载波的调制方式;声波换能器驱动电路和回波接收电路的设计。在此基础上,结合软件无线电思想,利用FPGA嵌入式数字信号处理平台实现可编程片上系统;建立声波扩频测距时延估计模型,研究数字信号处理优化算法,给出实验结果,分析和讨论测量精度问题。本文中研究的原理样机已经完成并通过测试,取得了比较理想的效果。更多还原

【Abstract】 The measurement of parameters of oil wells such as temperature, pressure and oil liquid level is the basic task for oil industry. The liquid level is an important basis for the decision of oil pressure, the productivity of oil well and the most reasonable mode of production.At present, the main method of oil liquid level measurement is based on sound pulse signal which is produced by explosive sound source. The sound pulse propagates along the petroleum pipeline and reflexes when reaching the oil level. This signal is received by rheomicrophone and processed by microcontroller. The propagation delay time is calculated to estimate the depth of oil level. Although some filtering and correlation algorithms can be applied to improve signal to noise rate in order to recognize coupling wave and level wave better, pulse distance measuring is interfered by noise wave easily. At the same time the accuracy and depth of measuring is limited meanwhile the security can not be guaranteed. The theory of spread spectrum is lead in oil level measuring in this article in order to solve the problems, using low power density spread spectrum sound signals to measure the oil level accurately.The main content of this article includes as follows.The acoustics basic principle and the feature of sound wave propagating in the pipeline are introduced.The principle of spread spectrum especially the advantage of spread spectrum distance measuring is discussed. The parameter of m sequence and the method of modulation of sound wave carrier are analyzed.According to the environment in the pipeline, the driver circuit of sound wave transducer and high-precision echo receiving circuit are designed. The platform of FPGA embedded signal processing based on the idea of software radio is set up to achieve the architecture of system on programmable chip (SOPC).The time delay estimation model of sound wave spread spectrum system is established with the optimization of algorithm. Finally, the result of experiment is discussed and analyzed.The prototype introduced in this paper has been completed and tested, achieving some satisfactory results.更多还原