油基泥浆测井仪多通道采集模块设计

发布时间：2017-12-26 18:16

本文关键词：油基泥浆测井仪多通道采集模块设计　出处：《电子科技大学》2016年硕士论文　论文类型：学位论文

【摘要】：近年来国内外正争相研发具有自主知识产权的油基泥浆测井仪,因为油基泥浆相比于常规的水基泥浆具有耐高温、耐腐蚀、增强井眼稳定性、提高钻井效率等优点,且能够适应水基泥浆的测井环境。多通道采集模块是油基泥浆测井仪最为关键的功能模块之一,其主要作用是检测流经纽扣电极的电流信号,并且完成小信号的提取、放大、滤波、采集和数据运算等功能,接收处理模块下发的命令并进行数据传输。采集模块的性能直接决定了测井仪对地层电阻率测量的精确度。由于多通道采集模块采集的是极微弱的电流信号,本文对油基泥浆测井仪采集模块的噪声进行了全面的分析,建立了噪声的数学模型,并且根据数学模型采取了在算法和电路设计上抑制噪声的方法。在多通道采集模块的后续的模拟电路设计及数字逻辑设计上考虑并遵循抑制噪声,提高信噪比的原则,有助于油基泥浆测井仪更精确地测量地层的电阻率。并且建立采集模块的电流输入模型,通过数学推导,分析了采集模块信号提取电路内电阻阻值对地层阻抗测量的干扰程度。本文主要涉及的内容有电阻热噪声分析,运放固有噪声分析,模数转换器固有噪声分析,模拟开关串扰噪声分析,模拟开关切换噪声分析及线上串扰噪声分析,考虑杂散电容时ADC外围电路设计,接地分割及跨地系统信号的处理,微弱电流信号提取、调理电路设计,锁相环同步方案设计等,并且在算法上应用了能够提高测量精度的数字相敏检波算法。最后根据多通道采集模块的指标要求,通过一系列实验验证了模块设计的合理性与正确性。其中测井周期时间实验验证了测井时间满足指标要求,通道内校准实验验证了内校准通道设计的合理性,电流电压采集同步实验验证了锁相环同步方案的正确性,高温实验验证了模块在高温下工作的性能,电流采集电路噪声抑制试验验证了采集模块对噪声的抑制能力,小电流实验验证了采集模块电流检测能力,井下实地测井实验验证了采集模块符合整支仪器的测井需求。
[Abstract]:In recent years at home and abroad are scrambling to develop the oil base mud logging instrument with independent intellectual property rights, because the oil base mud compared to conventional water base mud has the advantages of high temperature resistance, corrosion resistance, enhance wellbore stability, improve drilling efficiency, and can adapt to the environment of water base mud logging. Multi channel data acquisition module is one of the most important functional modules of oil based mud logging instrument, its main function is to detect electrical signals through the button, and complete the function of extraction, amplification, signal filtering, data acquisition and calculation, receiving and processing module issued orders and data transmission. The performance of the acquisition module directly determines the accuracy of the logging instrument to measure the resistivity of the formation. Because of the multi-channel acquisition module is the current extremely weak signal, the noise of oil based mud logging acquisition module is analyzed. The mathematical model is established according to the mathematical model of noise, and adopted a method to suppress the noise in the circuit design and algorithm. In the subsequent analog circuit design and digital logic design of multi-channel acquisition module, the principle of suppressing noise and improving signal-to-noise ratio is considered and followed, which helps oil well mud logging tool to measure resistivity of formation more accurately. And the current input model of the acquisition module is set up. The interference degree of the resistance value in the signal acquisition circuit of the acquisition module to the formation impedance measurement is analyzed by mathematical deduction. In this paper, the main contents are the analysis of resistance thermal noise, analysis of the inherent noise amplifier, analog-to-digital converter analysis of inherent noise analysis, analog switch crosstalk noise, noise analysis and simulation analysis of switching line crosstalk noise, ADC peripheral circuit design considering the stray capacitance, grounding system and cross signal segmentation, extraction, weak current signal the design of the regulating circuit, PLL design, and the application can improve the measurement accuracy of the digital phase sensitive detection algorithm in the algorithm. Finally, according to the requirements of the multi-channel acquisition module, the rationality and correctness of the module design are verified through a series of experiments. The cycle time logging experiments verify the logging time meet the requirements, the channel calibration experiments verify the rationality of the design of internal calibration channel, current and voltage acquisition synchronization experiment verified the correctness of PLL synchronization scheme, high temperature experiments verify the performance module work under high temperature, verify the inhibition ability of the module of collection of noise the current collecting circuit inhibition test, small current experiments verify the current acquisition module detection ability, downhole logging field experiments with a log collection module demand instrument.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TP274.2

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