Research on simulation design of electromagnetic transmission underground based on magnetic dipole

In order to solve the engineering technical problem of real-time downhole transmission of near drill bit logging data across power drilling tools through electromagnetic waves, this article innovatively builds an electromagnetic short-range transmission proportional simulation model for the 8 1/2 “wellbore of a horizontal well based on the principle of magnetic dipole transmission. For the first time, multiple factors such as mud, formation and metal drill collar conductivity, dipole antenna and excitation signal key parameters, antenna protection cover insulation tape size, etc. are comprehensively proposed for electromagnetic transmission simulation. The simulation results show that the influence of drilling fluid medium can be ignored when the electromagnetic signal frequency is less than 500 kHz. The antenna inductance in the 500 kHz frequency band is preferably not greater than 1 mH, and the axial width of the antenna protection cover insulation tape is greater than 5 cm. The amplitude of the received signal remains basically unchanged. Design two sets of prototypes with carrier frequencies of 500 kHz and 62.5 kHz based on the comprehensive simulation results. The on-site test results of the prototype have verified that the simulation design provides clear and effective quantitative guidance for the optimization of key parameters of the electromagnetic transmission prototype.