电磁波电阻率测井的二维全参数反演  

2-D Full-Parameter Inversion of Electromagnetic Wave Resistivity Log

作　　者：康俊佐[1] 杨善德[2] 

机构地区：[1]青岛科技大学数理学院,山东青岛266061 [2]吉林大学物理学院,吉林长春130023

出　　处：《测井技术》2007年第4期314-320,334,共8页Well Logging Technology

基　　金：青岛科技大学科研启动基金资助

摘　　要：电磁波电阻率(EWR)测井仪可给出4条相位差和4条幅度比测井曲线,但它们的视电阻率值与相应的地层真值相差较大,要得到好的解释效果,还必须对它们做二维反演。在一组具有不同层厚、不同电阻率的23层数值模拟地层模型中正演计算了EWR的测井响应并分析了它们的性能,从它的8条曲线中挑选出了探测深度分布比较合理的5条。利用其中分辨率最高的P2曲线的一阶导数特征点提取的地层纵向边界数值的基础上,先对它们做纵向一维反演;利用一维反演结果作为二维反演模型的初值,采用适合于对地层几何参数和电参数同时进行反演的改进的阻尼型高斯-牛顿正则化算法,实现了EWR资料的二维全参数反演。该方法较好地重建了包括低电阻率环带在内的地层模型参数,开发了它的直观识别低电阻率环带的能力,提高了EWR的资料解释水平。The Electromagnetic Wave Resistivity （EWR） tool of the Sperry Sun outputs 4 phase difference curves and 4 amplitude ratio curves, however, the differences between their derived apparent resistivities and true resistivities of formation are rather large. It is necessary to do their 2-dimensional inversion for obtaining better interpretation effectiveness. Its logging responses are forward calculated in a simulated formation model of 23 layers with different thicknesses and different resitivities, and their performances are analyzed, then 5 logging curves with reasonable distribution of investigation depth are selected from the 8 outputs. Based on vertical boundaries of layers extracted from characteristic points of the 1st derivative of the P2 curve, which has the best vertical resolution in the 5 curves, 1-D inversions are completed with the 5 curves firstly, then utilizing the results of the 1-D inversions as the initial values of a 2-D inversion model, an improved damping regularized Gauss-Newton optimization algorithm, which is suitable to simultaneous inversion with geometry and electrical parameters of layers, is applied to complete the full-parameter inversion of EWR data. The method reconstructs parameters of layers, including parameters of low resistivity annulus, develops a capability in directly identifying low resistivity annulus, improves the EWR interpretation.

关 键 词：电磁波电阻率(EWR) 视电阻率曲线 低电阻率 二维反演 高斯-牛顿优化算法 

分 类 号：P631.84[天文地球—地质矿产勘探]