Abstract:

The principle of array lateral sonde and the fast forward calculationsimulation of the cylindrical electrode with a point source were first introduced  and the characteristics of the responses were analyzed and summarized based on the forward calculation of different models. The nonlinearity between the shallowest mode’s response(ρ_a0) and the mud resistivity(ρ_m)dropped off with the increasing of borehole diameter and the true resistivity(ρ_t  ). The responses of the lowinvasion model increased, and that of the highinvasion model disordered, with the changing of invasion radius under different borehole diameters. The responses near the interface sometimes oscillated for the model with shoulder layer and invasion. These characteristics can beused as a priori information to study of the logging interpretation and inversion, and also as a theoretical basis to analyze the loggingresponses.

Key words: array lateral logging;forward response; characteristic analysis