钻柱对地面钻孔EM-MWD信号传输影响的ANSYS模拟分析

钻柱是电磁波随钻测量（EM-MWD）信号传输的重要信道，评价EM-MWD信号传输效果，不可忽视钻柱的影响。基于此，采用ANSYS有限元软件，对EM-MWD信号传输特性进行仿真。从地面接收电压和电流密度两方面，分析了孔眼环空横截面积、钻柱横截面积、钻柱电阻率和绝缘短节位置对电磁波随钻测量信号传输的影响规律。仿真结果表明：地面接收信号随钻柱横截面积增大而增强，受孔眼环空间隙影响小；钻柱电阻率越低，接收信号越强；绝缘短节与钻头之间的距离越长，接收信号越强。

ANSYS simulation analysis on the influence of drill string on EM-MWD signal transmission of surface borehole

Drill-string is the important channel of EM-MWD (Electromagnetic measurement while drilling) signal transmission. The influence of drill-string can not be ignored when evaluating the transmission effect of EM-MWD signal transmission. Therefore, the finite element method is employed to simulate the characteristics of EM-MWD signal transmission. To analyze the influence laws of factor on EM-MWD signal transmission, which includes the cross-sectional area of annulus, the cross-sectional area of drill-string, the resistivity of drill-string and insulation nipple position through ground current density and ground receiver voltage. The simulation results show that signal intensity will be increased with the increase of drill-string cross-sectional area and the distance between drill bit and insulation nipple, but has nothing to do with annulus cross-sectional area. Signal intensity will be increased with the drill-string resistivity.