MCI微电阻率成像测井仪数字相敏检波的改进

Improvement of Digital Phase Sensitivity Detection in Micro-conductivity Imaging Logging Tool

介绍了微电阻率成像测井仪MCI（Micro-conductivity Imaging Logging Tool）检测系统原理及其所存在的不足，对其进行了优化处理。阐述了数字相敏检波的基本原理，给出线性逼近算法的优缺点，针对该算法精度不高的缺点提出一种线性逼近和牛顿拉夫逊相结合的新算法。给出了新算法的程序流程图以及新算法与线性逼近算法的相对误差比较结果。新开方算法能够满足测井实时计算的要求，提高信号检测的精度，从而提高微电阻率成像测井仪的成像质量。

Introduced are detection system principle and disadvantages of the micro-conductivity imaging logging tool（MCI）, and an optimization method is presented. Stated are the basic theory of DPSD（Digital Phase Sensitivity Detection）, advantage and disadvantage of the line-approaching method. In order to obtain algorithm precision, we provide a new algorithm by combining the line -approaching method and the Newton-Raphson method, and give its calculation flow chart. Rela- tive error comparison result of the 2 algorithms shows that the new algorithm is better than line- approaching method in both accuracy and linearity. Practical applications show that new algo rithm meets the requirement of real-time calculation and can boost image quality of micro-conductivity imaging log by improving signal detection precision.