一种新的趋肤效应校正方法

A New Method of Skin Effect Correction

趋肤效应影响使感应测井测量值低于地层真电导率。根据均匀地层感应测井视电导率实部与频率和地层电导率的函数关系提出了一种双频率校正与归一化校正相结合的趋肤效应校正新方法。该方法先用2个频率计算视电导率随不同频率平方根变化的一阶导数,补偿高频信号的趋肤效应影响实现双频率趋肤效应校正。以此为基础设计了一种兼顾低、中、高宽地层电阻率范围的三频率趋肤效应校正方法。高频保证高电阻率地层中测量信号大、稳定;低频考虑低电阻率地层中趋肤效应影响不能太大;中频选择兼顾高低频信号。仪器实现中,要求发射线圈同时发射3个频率信号,所有子阵列都接收3个频率信号。测量数据处理时,分别用高、中频率和中、低频率进行双频率趋肤效应校正,得到2组校正后的数据,使感应测井仪器适应较宽范围的地层电阻率测量。双频率趋肤效应校正后,视电导率的非线性得到了极大改善,进一步采用归一化趋肤效应校正方法可以消除残余的误差。可用于新型感应测井仪器设计中。

Due to skin effect,the measurement of induction logging is lower than the true formation conductivity.Put forward is a new method of skin effect correction based on function relationship between the real part of apparent conductivity against frequency and true formation conductivity in uniform formation condition.The first step of the new method is to correct skin effect by first order derivative of apparent conductivity to square root of frequency with two frequencies.In the second step,the residual error is further corrected by a normalization method.According to the method,a new skin effect correction scheme using 3-frequency is designed.It is suitable to a wide formation conductivity range from low to high.Testing result shows that this new method is effective,simple and easy to be calculated and implemented.This scheme can be used in design of a new type of array induction logging tool.