Research on the Characteristics of Electromagnetic Wireless Transmission Channels in Oil Wells

Downhole pressure and temperature monitoring of oil production wells is one of the effective means to ensure normal and efficient development of oil and gas wells. Aiming at the problems of the conventional ways such as downhole storage manometer, the method is proposed which transmit downhole information using wireless low-frequency electromagnetic wave. Firstly, an electromagnetic wave transmission channel model for oil wells was established based on the equivalent transmission line theory, considering factors such as tubing, casing, and annular media. Secondly, the channel model was simulated using COMSOL Multiphysics software to analyze the impact of frequency and casing contact on the transmission of electromagnetic signals in oil wells, providing a theoretical basis for the application of electromagnetic wave wireless transmission technology in oil and gas wells. The simulation results show that:(1) At the same transmission depth, as the frequency of the electromagnetic signal increases, the voltage received on the ground continuously decreases. (2) When the oil casing is in contact, the contact impedance on the coupling channel decreases due to the short-circuit effect, resulting in an increased signal amplitude received at the surface.