【作者】 蒋奇云；

【导师】 何继善；

【作者基本信息】 中南大学 ， 地球探测与信息技术， 2010， 博士

【摘要】 广域电磁法是何继善院士提出的。他针对现有可控源电磁法要求“远区”测量而导致信号微弱和一次只发送、接收一个频率的缺点,将现有可控源电磁法理论进行了创新,并发明了伪随机信号。伪随机信号包含多个振幅接近、频率在对数坐标分布均匀的多频信号,是一种理想的电磁法勘探场源。广域电磁法继承了CSAMT场源可控的优点,从而克服了MT场源随机性和信号微弱的缺点。该方法并不沿用“卡尼亚视电阻率”计算公式,而是用电磁场的全域精确公式迭代计算提取视电阻率,这样可以在“非远区”进行测量,大大拓展了人工源电磁法的观测范围,提高了观测速度、精度和野外勘探效率。广域伪随机电磁法是一种全新的独具特色的电磁勘探方法。广域伪随机电磁测深仪以广域电磁法理论为指导,在设计思路和原理上突破了一些陈旧观念,打破国外电磁法仪器一统天下的局面。它实现了自主创新,拥有自主知识产权,推动了电磁法仪器的进一步发展。广域视电阻率可以通过测量电磁场的任一分量获得,但测量电场的水平分量Ex相对简便。结合现代电磁法仪器新技术,本文研究了基于E-Ex广域电磁测深法的测量仪器系统,包括适合在深部油气藏地区实施深部三维电磁勘探的大功率伪随机信号发送机和广域电磁接收机。本文首先根据伪随机信号的基本原理,论述了伪随机信号波形产生机制和伪随机信号发送控制器的设计；详细探讨了伪随机信号发送机的功率设计、大功率整流滤波以及逆变技术和实现方法；设计了200KW大功率整流滤波器、IGBT逆变器Matlab模型并进行仿真分析；阐述了IGBT驱动与无源无损缓冲电路设计,实现了IGBT的过压、过流检测与保护电路设计；分析了发送机所用大功率半导体器件的耗散功率设计,采用新型热管散热技术为功率半导体散热,保证大功率伪随机信号发送机的可靠运行。本文还详细分析了E-Ex广域电磁有效信号和干扰信号的频率、振幅等特征；探讨了模拟、数字选频技术,实现了基于GPS同步的相干检测；提出了接收信号数字化思想,详细推导了伪随机多频信号的提取方法,用matlab进行了仿真分析,并在DSP处理器里实现了提取算法；设计了低噪声精密模拟信号调理电路,实现了高速、高分辨模数转换；阐述了基于TMS320C6713 DSP核心系统以及网络通信接口、数据采集接口和GPS接口设计；实现了DSP软件功能设计和程序编制。提出并实现了基于光纤通信的网络通信系统和基于Canopy的无线网络通信系统,实现了广域电磁三维勘探。广域电磁接收机室内电阻网络指标测试(包括一致性、稳定性等),以及广域电磁测深仪器系统(包括200KW发送机和多台接收机)在油田地区的野外试验表明：研制的广域电磁测深仪达到了设计指标,基本满足野外三维电磁勘探要求,为实现和推广广域电磁法提供了必备条件,具有重要的实际应用意义。论文获得了国家自然科学基金项目：科学仪器基础研究专项基金“广域电磁测深仪的基础研究(40827002)”的资助。更多还原

【Abstract】 The wide field electromagnetic sounding method is presented by academician He Ji-shan. He puts a theoretical innovation based on the existing CSAMT arming at weak signal caused by measurement in remote area and sending and receiving frequency one by one, associated with pseudo-random signal method which is an ideal source of electromagnetic exploration because of the near amplitude and homogeneous distribution in logarithmic scale of primary frequencies. Wide field electromagnetic method inherits the advantage of controlled source in CSAMT, then overcomes the shortcomings of random source and weak signal in MT. It doesn’t continue to use "cagniard apparent resistivity" formula, but use accurate formula of electromagnetic field to extract the apparent resistivity by iteration method to measure in non-remote area, greatly expands exploration range of controlled sources electromagnetics, and has an improvement on the observed speed, accuracy and efficiency of field exploration. Wide field Pseudo-random signal electromagnetic method is a new and unique electromagnetic method for exploring.Wide field pseudo-random electromagnetic sounding system was based on wide field electromagnetics sounding method, broke through some outdated concepts on thoughts and principles of design, broke down the foreign domination on electromagnetic instruments. It realized innovation independently and held independent intellectual property rights,which would promote the further development of electromagnetic instruments.The apparent resistivity of wide field electromagnetic sounding method can be achieved by measuring any component of the electromagnetic field, but the measurement of the horizontal component in the electric field is relatively simple. The paper researches sounding systems based on E-Ex wide field electromagnetic sounding method which integrates the hot technologies of the modern electromagnetic instruments and includes high-power pseudo-random signal transmitter and receivers for 3D EM exploration in the deep hydrocarbon reservoir, According to the theory of pseudo-random signal, the paper discusses the generating principle of pseudo-random signal waveform and the design of transmitting controller corresponding, probes the power design,, high power rectifier and filter, and inverter technology of transmitter in detail, designs the Matlab models on rectifier, filter and IGBT inverter of 200KW power, then simulates and analyzes it, describes the design of IGBT’s drive and passive lossless buffer, achieves the detection of over-voltage or over current and protection of IGBT, analyzes the wasted power of high-power semiconductor devices used in transmitter, and ensures reliable operation of transmitter by using the new heat pipe cooling technology for power semiconductor cooling.The paper analyzes the frequency and amplitude of effective signals and interference in E-Ex wide field electromagnetics, probes analog and digital frequency selection technology, realizes coherent detection based on GPS synchronization, proposes digitizing the receiving signal, deduces the process of the extraction of pseudo-random multi-frequency signal, and simulates and analyzes it in Matlab, and then achieves the extraction in DSP processor, designs low-noise precision analog signal conditioning circuit and high-speed, high-resolution analog-digital conversion, describes the core system based on TMS320C6713 DSP and network communication interface and data acquisition interface and the GPS interface, achieved software functional design and programming of DSP, proposes and achieves network communication system based on optical fiber and wireless network communication system based on Canopy, which can realize 3D exploration of wide field electromagnetics.Index tests indoor using resistor network of receivers (such as consistency and stability) and field tests in oil region of wide field electromagnetic sounding system (including 200KW transmitter and receivers) have shown that the system has achieved the prospective specifications, basically meets the requirements of 3D EM exploration, and provides the necessary condition for realizing and popularizing wide field electromagnetics, which has important practical significance.The paper won the funding of National Natural Science Foundation Project:Special Fund in Scientific Instruments Basic Research "the basic research of wide field electromagnetic sounding system (40827002) ".更多还原