基于ANSYS的接地发射电极对双向EM-MWD下传信号的影响分析

接地发射电极作为双向EM-MWD信号下传系统的必要组件，其合理参数设置可提高信号下传效果，但目前关于其对下传信号的影响规律认知甚少。基于双向EM-MWD工作机理，结合电流场理论，应用ANSYS有限元软件，建立双向EM-MWD信号下传三维仿真模型，研究接地发射电极的发射距离、长度、直径和电阻率对下传信号传输的影响。结果表明:下传信号接收效果与接地发射电极直径及长度呈现正相关关系；接地发射电极电阻率小于10-4 ?·m时，其电阻率变化对下行信号传输的影响小，常规金属材料即可满足对电阻率的要求；随着双向EM-MWD地面发射距离的增加，下传信号接收强度先快速增强，超过一定距离后，信号强度趋向定值。 

Analysis on influence of ground transmitting electrode on bidirectional EM-MWD signal transmission based on ANSYS

The grounded emitter electrode is a necessary component of the bidirectional EM-MWD signal downlink system, and its reasonable parameter setting can improve the signal downlink effect, but at present, little is known about its influence on the downlink signal. This paper is based on the bi-directional EM-MWD working mechanism, combined with the current field theory, using ANSYS finite element software, establishes a three-dimensional simulation model of bidirectional EM-MWD signals, and analyzes the emission distance, length, diameter and resistivity of the ground transmitting electrode versus the downlink signal. The simulation results show that the downlink signal reception effect is positively correlated with the diameter and length of the ground transmitting electrode; when the grounded emitter electrode resistivity is less than 10-4 ?·m, its resistivity change has little influence on the downlink signal transmission, the conventional metal material can meet the requirement of resistivity; as the transmission distance of the bidirectional EM-MWD increases, the received signal strength of the downlink signal increases rapidly first, after exceeding a certain distance, the signal strength tends to be fixed.