多频电磁波传播测井信号测量系统  

Signal measurement system of multi-frequency electromagnetic wave propagation logging

作　　者：贾将 宋瑞林 赵军[1] 李永龙 汪英杰 谭锦林 黄靖浩 JIA Jiang;SONG RuiLin;ZHAO Jun;LI YongLong;WANG YingJie;TAN JinLin;HUANG JingHao(School of Geoscience and Technology,Southwest Petroleum University,Chengdu 610500,China;School of Electrical Engineering and Information,Southwest Petroleum University,Chengdu 610500,China;Southwest Geophysical Exploration Branch of CNPC Orient Geophysical Exploration Co.,Ltd.,Chengdu 610200,China)

机构地区：[1]西南石油大学地球科学与技术学院,成都610500 [2]西南石油大学电气信息学院,成都610500 [3]中国石油集团东方地球物理勘探有限责任公司西南物探分公司,成都610200

出　　处：《地球物理学进展》2022年第6期2562-2570,共9页Progress in Geophysics

基　　金：国家留学基金委国家建设高水平大学公派研究生项目(201906440082)资助。

摘　　要：大量岩石物理实验研究证实地层的复电阻率频谱信息在储层评价方面具有广阔的应用前景,开展多频电阻率测井相关技术研究有利于相应岩石物理研究成果的落地推广.本文基于电磁波传播测井原理对多频电阻率测井的信号测量技术进行了研究.信号测量系统的核心单元为数字信号处理芯片DSP,配合高频VGA(可变增益放大器)芯片和数模转换器实现了高宽频带信号的可编程增益放大.为简化系统结构并降低硬件成本,利用直接频率合成器DDS、乘法器和低通滤波单元对测量信号在不损失信号幅度和相位信息的条件下进行了降频处理,降频后的信号频率固定为50 kHz,与测量信号无关.利用高精度模数转换芯片和FIFO缓存芯片,配合的DFT算法实现了两路高频信号相位和幅度的高速采集计算.由于检波信号频率固定且与测量信号频率无关,DFT算法得以简化以提升幅相分析效率.设计了幅度比和相位差已知的刻度电路对信号测量系统在250 kHz~8 MHz频带内的测量性能进行了测试,在测试频带内的相位差测量绝对误差低于0.3°,幅度比测量绝对误差小于0.6 dB.设计的多频电磁波传播测井信号测量系统具有稳定的测量精度,研究成果对于多频电磁波传播测井的工业化研发具有推动作用.A large number of petrophysical experimental studies have confirmed that the complex resistivity spectrum of the formation has broad application prospects in reservoir evaluation.The development of multi-frequency resistivity logging technology research is conducive to the application of corresponding petrophysical research results.The research of signal measurement technology of multi-frequency resistivity logging based on the principle of electromagnetic wave propagation logging was carried in this study.The core unit of the measurement system is the DSP(Digital Signal Processor),which cooperates with the high-frequency VGA(Variable Gain Amplifier)chip and the DAC(Digital-to-Analog Converter)to realize the programmable gain amplification of the high-bandwidth signal.In order to simplify the structure of the measurement system and reduce the hardware cost,the direct frequency synthesizer DDS,multiplier chip and low-pass filter unit were used to reduce the frequency of the measured signal without losing signal amplitude and phase information.The frequency of the frequency-reduced signal is fixed at 50 kHz,which has nothing to do with the measured signal frequency.High-speed acquisition and calculation of the phase and amplitude of two high-frequency signals were realized by high-precision ADC(Analog-to-Digital Converter)and FIFO buffer chip with DFT algorithm.Since the detection frequency is fixed and independent of the measurement frequency,the DFT algorithm was simplified to improve the efficiency of amplitude and phase analysis.A calibration circuit with a known amplitude ratio and phase difference was designed to test the performance of the signal measurement system in the frequency band of 250 kHz-8 MHz.The absolute error of the phase difference measurement in the test frequency band is less than 0.3°and the absolute error of amplitude ratio measurement is less than 0.6 dB.The designed signal measurement system of multi-frequency electromagnetic wave propagation logging has stable measurement accuracy,and t

关 键 词：多频 电磁波传播测井 降频 信号处理 

分 类 号：P631[天文地球—地质矿产勘探]