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.