Evaluation of Extraction and Enhancement of Response due to Target Inhomogeneities for Resistivity Interpretation

Abstract

The future effectiveness of the resistivity method depends upon its ability to interpret field data obtained under more complex geological structure environments. Generally, the effects of nontarget surroundings such as weathered overburden layers, vertical contacts, faults, fracture zones, deep bed rocks or host rocks, near-surface lateral or local inhomogeneities and topography are noises for exploration, and only the response due to the target is a signal. In these various resistivity environments, it is very important to know how to reduce the nontarget inhomomeneity effects. Also, one must be careful when applying the homogeneous medium interpretation techniques to actual field data processing. In this paper, the following points are discussed ; ( 1 ) Normalization of the noises caused by geologic structures in order to extract and enhance the response (signal) due to the target inhomogeneities. ( 2 ) Significance of expression procedure in an evaluation of resistivity interpretation process and results. ( 3 ) Sensitivity distribution newly developed by using the FEM 2D-3D algorithm in the case of nontarget inhomogeneities. Also, the sensitivity difference of its application that is effective to evaluate the extraction and enhancement of the response (signal) due to the target inhomogeneities in various surroundings.