利用分离变量法计算电磁波电阻率仪器的测井响应

研究随钻电磁波电阻率仪器中线圈系电磁响应的计算方法,对于测井数据的快速反演具有重要的意义。从Maxwell方程出发,导出了修正磁矢位满足的泊松方程,并采用分离变量法和电磁场边界条件导出了圆电流环在径向分层介质中的磁矢位的解析解,该方法形式简洁,易于编程,精度高。利用上述方法对随钻电磁波电阻率测量仪器进行了建模和计算,并分析了钻铤刻度曲线和井眼校正方法,所得到的结论对于随钻电磁波电阻率测量仪器的研制具有重要的理论价值和实际意义。

Calculating the logging response of electromagnetic-wave resistivity instrument by using separation of variables

Researching on the computational methods of the electromagnetic response to the coil system in the electromagnetic wave resistivity(EWR) logging-while-drilling(LWD) tool had great significance in the fast inversion of log data.Starting from the Maxwell’s equations,the Poisson’s equation for the modified magnetic vector potential is derived,and the analytical solution of the magnetic vector potential due to the circular current loop in the radially stratified media is obtained by using the method of separation of variables and boundary condition of the electromagnetic field.This method is simple,easy to be programmed,and with high precision.The logging-while-drilling(LWD) tool for electromagnetic wave resistivity(EWR) measurement is modeled and calculated,and the scale-curves of the drilling collar and borehole correction method are analyzed.These results have important theoretical value and practical significance in designing LWD tools for EWR measurement.