随钻电磁波测井仪器线圈系参数设计方法研究  

On Coil System Design for MWD Electromagnetic Wave Logging Tools

作　　者：赵媛[1] 顿月芹[1] 袁建生[1] 

机构地区：[1]清华大学电机工程与应用电子技术系电力系统国家重点实验室,北京100084

出　　处：《测井技术》2011年第3期224-229,共6页Well Logging Technology

摘　　要：随钻电磁波测井仪器的关键结构是发射和接收线圈系,主要包含工作频率、线圈间距和源距等3个参数,且这3个参数相互制约。在分析随钻电磁波测井基本原理的基础上,通过数值仿真研究了仪器线圈系关键参数的设计方法。在满足待测地层电导率范围、钻井液电导率、探测深度和可分辨最薄水平地层厚度等探测要求的前提下,并考虑到接收线圈测量精度要求,给出了线圈系参数的设计原则和变化特性。仿真结果表明,工作频率主要受地层电导率、介电常数和能探测的最小相位差等影响;同时,降低工作频率可以增加径向探测深度,但会减小水平薄层分辨率。线圈间距主要受地层中电磁波波长和探测最薄地层厚度等影响;同时,缩小线圈间距能够提高水平薄层分辨率,但间距过小会影响仪器对相位差的分辨。源距主要影响探测深度,增大源距能够增加径向探测深度,但源距过大会使信号衰减太大而影响接收信号。研究结果可作为工程实际中仪器线圈系设计的理论依据。The coil system with transmitting and receiving antennas at a fixed frequency is the key structure of electromagnetic logging-while-drilling tools. In this paper, the basic principles of e- lectromagnetic wave logging-while-drilling are studied. The key design parameters including the source frequency, the transmitter-receiver spacing and the receiver interval are analyzed, and the principles and steps of coil system design are given. A critical requirement in the design of the coils system is to produce different desired signals for different typical ground models. The pa- rameters must be reasonable values to achieve the desired effect. The simulation results show that the source frequency is affected by conductivity, dielectric constant and the required precision of minimum phase difference. The lower frequency can increase the investigating depth, but will reduce the investigating characteristic of thin layers. The receiver interval is affected by the mini- mum electromagnetic wavelength, the required precision of minimum phase difference and the minimum thickness of the horizontally thin-layer that can be detected. Reducing the receiver in- terval can improve investigating characteristics of thin layers, but if the spacing is too small, it will affect the resolution of the phase difference. The transmitter-receiver spacing can affect the investigating depth. It can increase the investigating depth, but too larger spacing will make the signals too small. The results provide a valuable reference for the design of electromagnetic log- ging-while-drilling tools.

关 键 词：随钻电磁波测井 线圈系 参数 设计 探测特性 

分 类 号：P631.33[天文地球—地质矿产勘探]