阵列侧向测井正演响应的特性分析

在介绍阵列侧向电极系工作原理及点源模拟柱状电极快速正演算法的基础上,基于不同模型的正演计算,分析总结其响应特性。随井径和目的层电阻率ρ_t的增大,最浅探测模式的响应ρ_a0与泥浆电阻率ρ_m之间的非线性减弱;不同井径下随侵入半径的变化,低侵模型各模式(由浅探测至深探测)的响应有递增关系,而高侵模型的响应出现乱序;对有围岩有侵入模型,层界面附近的响应有时存在震荡现象。这些特性可用于阵列侧向测井响应的解释和反演研究,同时也为测井工程师分析测井响应提供了理论基础。

Characteristic analysis of the forward response of array lateral logging

s: The principle of array lateral sonde and the fast forward calculation simulation 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 calcula-tion of different models. The nonlinearity between the shallowest mode's rcsponse(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 berehole diameters. The responses near the interface sometimes oscillated for the model with shotdder layer and invasion. These characteristics can be used as a prio-ri information to study of the logging interpretation and inversion, and also as a theoretical basis to analyze the logging responses.