基于霍尔效应测量过套管地层电阻率理论及模拟实验研究

Theory and Simulation Experimental Study on Formation Resistivity Measurement through Casing Based on Hall Effect

近年来,过套管地层电阻率测量技术在气水识别、剩余油评价以及油藏流体饱和度动态监测等方面都显示出很强的实用价值和现实意义。文章在掌握过套管电阻率测量原理的基础之上,将实验与理论相结合,利用霍尔效应原理研究存在金属套管条件下管外电阻率(模拟过套管地层电阻率测量条件)测量信号的变化特点和影响因素。通过模拟实验测量,对比分析了4种理想介质条件下金属套管外电场响应特征,分析发现在磁场强度一定的条件下,测量电压信号与电流强度有明显的相关性;改变套管外电阻率值,测量电压随之发生变化,且随着管外地层电阻率值的增加,电压逐渐增大;测量电压值的大小不仅受磁场强度的影响,还与套管壁的光滑程度、水泥厚度等多种因素有关。该实验结果为后期国内过套管电阻率测井仪器的研制提供了新的思路和方法。

In recent years,the technique of through casing formation resistivity logging shows great practical value and practical significance in gas-water identification,residual oil evaluation,reservoir fluid saturation dynamic monitoring and other aspects.In this paper,based on the understanding of the resistivity measurement principle through casing,combining experiment with theory,using Hall Effect principle,the variation characteristics and influence factors of the resistivity measurement signal outside casing(simulating the resistivity measurement condition of through casing formation)under the presence of metal casing are studied.Through simulated experimental measurement,the response characteristics of external electric field of metal bushing under four kinds of ideal media conditions are compared and analyzed.It is found that there is an obvious correlation between measured voltage signal and current intensity under the condition of certain magnetic field intensity.The measured voltage changes with the change of the resistivity outside the casing,and the voltage increases gradually with the increase of the resistivity outside the casing.The measured voltage value is not only affected by the magnetic field strength,but also by the smoothness of casing wall,cement thickness and other factors.The experimental results provide a new idea and method for the development of domestic resistivity logging instrument through casing in the later period.