基于井下仪器的工频噪声去除电路温度特性研究

Research on temperature characteristics of power frequency noise removal circuit based on downhole tool

为了减小井下仪器自然电位测井时50 Hz工频噪声对测量信号的影响,采用不同滤波电路对工频噪声进行滤除,经过实验测试和对比,提出一种用于地面和井下自然电位工频去噪的方法和电路。首先利用巴特沃斯低通滤波电路的方法,采用不同芯片进行对比测试和加温试验,继续优化的工频滤波电路,经过测试和加温实验,能够很好的满足160℃温度范围内减小自然电位工频噪声的测井需求。结果表明该电路和方法能够很好地减小自然电位信号中的工频噪声,可以适用于所有电法仪器(侧向类仪器、激发极化类仪器等)具有地面回路电极的工频滤波需求。

In order to reduce the influence of 50 Hz power frequency noise on the measurement signal during the spontaneous potential logging of the downhole tool, different filter circuits are used to filter the power frequency noise. After experimental testing and comparison, a method and circuit for power frequency denoising of surface and downhole SP are proposed. Using the method of Butterworth low-pass filter circuit, different chips are used for comparison and temperature test. Continue to optimize the power frequency filter circuit, after testing and heating experiments,the filter circuit can well meet the logging requirements of reducing the power frequency noise of the SP in the 160 ℃ range. The results show that the circuit and method can reduce the power frequency noise of SP signal very well. The circuit and method can be applied to all electrical tools(lateral tools, induced polarization tools, etc.) with ground loop electrodes for power frequency filtering requirements.