Analytical solution of electromagnetic field generated by induction logging tool in a fan-ring slot of drill collar while drilling  

作　　者：LIU FuPing WANG AnLing YANG ChangChun 

机构地区：[1]Beijing Institute of Graphic Communication,Beijing 102600,China [2]Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China

出　　处：《Science China(Technological Sciences)》2009年第7期2128-2137,共10页中国科学（技术科学英文版）

基　　金：Supported by the National Natural Science Foundation of China(Grant No.10705049);the Beijing Natural Science Foundation(Grant No.1083011);Fund-ing Project for Academic Human Resources Development in Institutions of Higher Learning[PHR(IHLB)]

摘　　要：Based on the structural characteristic of metal drill collar for induction logging while drilling, we have given the analytical formulae of lengthways fields Ez and Hz when the tool is located in a fan-ring shaped slot of drill collar by the boundary conditions of electromagnetic field, and derived the other components of electromagnetic field in and out the fan-ring slot from Ez and Hz. In the other intervals of formation, where the drill collar is a solid cylinder, the analytical formulae of field are educed through the method of variable coefficient. The total analytical solutions of field in whole space have been obtained. With the help of the analytical formulae, we have also given numerical examples and analyzed the distributive characteristic of electromagnetic field. From the computational results we find that the secondary scattering field Hz is in a linear relation with the conductivity of stratum. The characteristic of field is very useful for induction logging while drilling, which can be used to measure and analyze the logging responses of the stratum conductivity. This paper sets up a theoretical foundation for us to study the distrbutions of field and to direct the design of logging instruments.Based on the structural characteristic of metal drill collar for induction logging while drilling, we have given the analytical formulae of lengthways fields E z and H z when the tool is located in a fan-ring shaped slot of drill collar by the boundary conditions of electromagnetic field, and derived the other components of electromagnetic field in and out the fan-ring slot from E z and H z . In the other intervals of formation, where the drill collar is a solid cylinder, the analytical formulae of field are educed through the method of variable coefficient. The total analytical solutions of field in whole space have been obtained. With the help of the analytical formulae, we have also given numerical examples and analyzed the distributive characteristic of electromagnetic field. From the computational results we find that the secondary scattering field H z is in a linear relation with the conductivity of stratum. The characteristic of field is very useful for induction logging while drilling, which can be used to measure and analyze the logging responses of the stratum conductivity. This paper sets up a theoretical foundation for us to study the distrbutions of field and to direct the design of logging instruments.

关 键 词：drill collar LOGGING WHILE DRILLING INDUCTION LOGGING WHILE DRILLING fan-ring shaped slot 

分 类 号：TG669[金属学及工艺—金属切削加工及机床]