The comparisons between the improved numerical mode-matching method (NMM) and the traditional NMM using for resistivity logging

Abstract

Based on the analysis and comparison of existing numerical mode-matching method (NMM), an improved NMM is proposed in this paper. A new type of recursive formulas is derived by setting the proper positions for the unknown variables, and recursive formulas are unified to one form for the layers above and under source, avoiding the disadvantage of the traditional NMM to deduce the recursive formulas for the layers above and under source respectively. It is easy to understand and has concise physical meaning. But the incremental factor in the recursive formulas can’t be eliminated thoroughly, which may affect the calculation accuracy and stability. Finally, the merits and demerits of the improved method and the traditional one are summarizes.