过套管电阻率测井响应信号十分微弱,增强测量信号幅度对提高仪器测量精度、改善视电阻事计算结果的精确性具有重要意义;建立全空间有限厚度纵向、径向阶跃地层模型,针对近地表段为低阻、中阻和高阻三种地层模型,在MATLAB7.0环境下数值模拟分别得出了近地表段有/无水泥环封固条件下,套管上一、二阶电位差的分布;分析上、下供电模式下电位差分布特点,总结了近地表段水泥环对测井响应的影响,给出了不同地层条件下近地表段水泥封固的建议.%Because of the extremely weak signals it is important to enhance signals for improving the precision of instrument measurement and apparent resistivity calculation. Longitudinal and radial step- formation model of limited thickness in whole space is set up. Considering formation model with low, medium or high resistivity near-surface, first and second-order casing potential difference is separately obtained in MATLAB 7. 0 when there is or not cement sheath at near- surface formation. The influence of near- surface cement sheath on logging response is summarized based on the analysis for potential difference distribution feature of upper and lower power supply mode. Advices on near-surface cementing technology for different kinds of formation are proposed.
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