Abstract:

A new type of numerical mode-matching (NMM) theory is applied into numerical simulation of common resistivity logs. In analytical section, by the continuity of interface between the adjacent layers in electromagnetic field, the traditional reflection and transmission matrixes is improved, and relationship between up-going and down-going wave is derived. A new transition formula is firstly presented. The improved NMM method, avoiding complicated matrix inverse, is easy to understand and has concise physical meaning. Furthermore, according to reciprocal theory, the calculating speed for B-A-M is one time faster than that for A-M-N. By the experiments for two-layer and three-layer homogeneous media, this method is verified to be highly precise and effective comparing with FEM method and the previous NMM method. The core concept of new NMM is helpful to 3-dimension NMM and other geophysics method in stratum media.

Key words: numerical mode-matching method；transition matrix；resitivity logs, reciprocal theory