考虑收发线圈半径和长度的感应测井信号分析  

Induced logging signal analysis considering radius and length of transmitting and receiving coils

作　　者：管浩嘉 沈建国 GUAN HaoJia;SHEN JianGuo(School of Microelectronics,Tianjin University,Tianjin 300072,China)

机构地区：[1]天津大学微电子学院,天津300072

出　　处：《地球物理学进展》2023年第3期1119-1131,共13页Progress in Geophysics

基　　金：国家重点研发计划“超高层建筑深基坑施工安全技术与装备研究”(2016YFC0802008)资助。

摘　　要：在计算感应测井双线圈系的感应电动势时,通常假设收发线圈半径远小于线圈之间的距离L而且线圈轴向长度可以忽略.实际的收发线圈是具有半径和长度的,那么线圈的半径和长度会对感应测井信号有多少影响,什么情况下这种影响可以忽略,就是两个重要的问题.本文采用线性数字滤波法和自适应高斯求积法,对线圈半径、线圈长度的影响,线圈半径和长度的综合影响进行了研究.结果表明,线圈半径、长度对感应电动势的影响都随着L的增大而减小;线圈半径和长度对感应电动势的综合影响小于半径和长度的单独影响中的最大者.通过定义线圈距阈值,线圈距L达到多少时线圈半径和长度的影响可以忽略这一问题得到了定量的说明.之后,给出了一个具体的仪器的计算结果和分析.考虑到实际的激励信号不可能是虚函数,本文基于虚指数函数激励的感应电动势推导了正余弦激励的感应电动势,并进行了实验验证.Electromagnetic logging method is a branch of electrical logging,which refers to a general term for a class of methods that use the principle of electromagnetic induction to detect the electrical properties of the formation.Induction logging is a frequency domain electromagnetic logging method.When calculating the induced electromotive force of an induction logging dual-coil system,there are usually two assumptions.First,the radii of the transmitting coil and the receiving coil are much smaller than the distance L between the coils.Second,the axial lengths of the two coils are negligible.The actual transmitter coil and receiver coil have specific radii and lengths,which brings two questions that are worthy of consideration.First,how much will the radii and lengths of the coils affect the induction logging signal?Second,under what conditions can this effect be ignored?In this paper,therefore,the linear digital filtering method and the adaptive Gauss quadrature method are used to study the influence of coil radius and coil length,and the comprehensive influence of coil radius and length.The relative error is defined to quantitatively express the influence of radius and length on induced electromotive force.With the relative error,it is shown that the individual effects of the coil radius and length on the induced electromotive force,and the combined effect of the coil radius and length all decrease when L increases;the combined effect of coil radius and length on induced electromotive force is less than the largest of the individual effects of coil radius and length.The paper ulteriorly defines the coil distance threshold to quantitatively indicate when the influence of radius and length can be ignored:when the coil distance L exceeds the coil distance threshold,the effects of coil radius and length are negligible.After that,the paper presents the calculation results and analysis of a specific instrument.Considering that the actual excitation signal cannot be an imaginary function,the induced electromotive force of

关 键 词：双线圈系 线圈半径 线圈长度 线性数字滤波 高斯求积 

分 类 号：P631[天文地球—地质矿产勘探]