声电瞬变电磁测井方法研究

发布时间：2018-02-25 02:06

本文关键词： 声波瞬变电磁场实轴积分法地层电阻率　出处：《天津大学》2015年硕士论文　论文类型：学位论文

【摘要】：用于激发振动的压电管或压电片在高电压的冲击性下产生振动时还伴随有瞬变电磁场。该瞬变电磁信号在井中传播,接收探头得到的瞬变电磁信号携带地层的电导率信息。该瞬变电磁信号过去被当成干扰信号屏蔽掉,本文对该信号中所包含的地层电阻率信息进行了研究。首先分析了压电换能器的瞬态响应波形,归纳出了阶跃函数和高斯函数两种激发波形;其次详细推导了裸眼井中压电管激发的瞬变电磁响应计算公式——实轴积分法,并实现了相应的算法,获得了两种激发波形的响应;最后分析了Ez、H和Er的响应波形,结果发现Ez的幅度与地层电导率关系密切,随地层电导率变化很大,从其波形幅度中可识别出地层的电导率。在近源距Ez波形的最大值与地层电阻率呈近似的线性关系;地层电阻率之差与对应的Ez响应之差的最大值也呈近似的线性关系。随着源距的增加,以上的线性关系不再成立。通过Ez的测量可以直接获得地层电阻率。设计了阵列声波测井信号采集系统、发射系统和深度采集系统。信号采集系统实现了对接收探头感应信号的滤波放大、A/D转换、数据传输、数据处理和保存以及对采集到的波形实时显示等功能,可对毫伏级信号实现采集。深度采集系统实现了对光电编码器正反转的判断以及转动圈数计数。信号发射系统由深度采集系统给出的两个I/O口控制场效应管IFR460的导通与关断,从而实现发射信号的发射与停止。为进一步验证声电组合测井仪器提供了理论和实验基础。
[Abstract]:The piezoelectric tube or piezoelectric plate used to excite vibration is accompanied by a transient electromagnetic field when it is vibrated under high voltage impact. The transient electromagnetic signal propagates in a well. The transient electromagnetic signal received from the probe carries the conductivity information of the formation. The transient electromagnetic signal was used to be shielded as an interference signal. In this paper, the formation resistivity information contained in the signal is studied. Firstly, the transient response waveform of piezoelectric transducer is analyzed, and two excitation waveforms, step function and Gao Si function, are summed up. Secondly, the calculation formula of transient electromagnetic response induced by piezoelectric tube in open hole is deduced in detail, and the corresponding algorithm is realized, and the response of two excitation waveforms is obtained. Finally, the response waveforms of Ezh and er are analyzed. The results show that the amplitude of Ez is closely related to the formation conductivity, and the electric conductivity of anywhere layer varies greatly. The formation conductivity can be identified from the amplitude of the waveform, and the maximum value of the Ez waveform is approximately linear with the formation resistivity at near source distance. The difference between the resistivity and the maximum value of the corresponding Ez response is also approximately linear. The above linear relationship is no longer true. The formation resistivity can be obtained directly by measuring Ez. An array acoustic logging signal acquisition system is designed. Transmitting system and depth acquisition system. The signal acquisition system realizes the functions of filtering, amplifying and amplifying the sensing signal of the receiving probe, transmitting data, processing and saving the data, and displaying the acquired waveform in real time. It can collect millivolt level signal. The depth acquisition system can judge the positive and inverse rotation of photoelectric encoder and count the number of rotation coils. The signal transmitting system is controlled by two I / O ports of depth acquisition system to control the conduction and turn-off of FET IFR460. It provides theoretical and experimental basis for further verification of sonoelectric logging tools.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P631.811

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