Orthogonal Azimuthal Cross-square Arrays Electrical Resistivity Technique’s Kookiness on Detection for Angular Disposition of Electrical Anisotropy

The article gives an overview on the study that critically analysed the effect of azimuthal orientation of current electrodes on the detectability of angular disposition of vertical electrical anisotropy caused by geologic features. This is very useful in ascertaining the correct orientation of foliation plane for vertically fractured geologic system. Eight points were studied using a pair, named alpha and beta, of orthogonal azimuthal cross-square arrays by direct-current electrical soundings in order to isolate and establish the angular disposition of presumed hidden subsurface vertical fracture. The kookiness observed in the resultant field observations was in violation of the principle of reversibility of light raypath (Fermat’s Principle), upon which the electrical resistivity principle is based. Thus ultimately, the work has reviewed the correlation between theory and field observations and predicted the cause of the kookiness. The angular kookiness (deviation) was linked to dipping of plane of foliation that is in practice assumed to be zero. Moreover, the study suggests that angle of rotation of array is suppose to be much smaller than the determined angle of dip for correct evaluation of dipping angle.