电阻率剖面法对称四极装置视电阻率曲线分析

各向同性均匀半空间中球体异常的电阻率对称四极剖面法视电阻率曲线,当极距较大时,低阻球体正上方会出现一个极小值,高阻球体正上方会出现极大值,前人文献基本上是这样描述的。但是当供电极距减小到2.5倍球体半径以下时,类似偶极装置的视电阻率曲线,低阻球体在球心地面映射点不会出现极小值,而是出现一个局部极大值,视电阻率最小值在球心两侧对称出现;高阻球体在球心地面映射点上不会出现极大值,而是出现一个局部极小值,视电阻率最大值在球心两侧对称出现。

Analysis of Apparent-resistivity Curve of Collinear Symmetrical Four-electrode Arrays Profiling Method

In the case of sphere anomaly body is in the homogeneous half_space, previous studies describe apparent-resistivity curve of collinear symmetrical four-electrode arrays profiling method, when span of current electrode is wider, the least apparent-restivity value appears above the center of the sphere when the restivity of sphere is less than wallrock’s, the largest apparent-restivity value appears above the center of the sphere when restivity of sphere is larger than wallrock. However, when the span of current electrodes reduces to less than 2.5 times of radius of sphere, collinear symmetrical four-electrode arrays profiling method’s apparent-restivity curve is similar with dipole device’s, a local maximum appears above the center of sphere,and one minimum appears at each side of sphere center along the survey line symmetrically when the restivity of sphere is less than wallrock; a local minimum appears above the center of sphere, and one maximum appears at each side of sphere center along the survey line symmetrically when the restivity of sphere is larger than wallrock.