Waveguide Analysis of Radiofrequency Transmission in Well Tubulars for Electromagnetic Heating of Heavy Oil

This paper presents the numerical modelling and simulation of a 2D vertical well tubular model excited by a coaxial radiofrequency transmission line placed in its annular space for the purpose of downhole RF energy transmission. The study identifies the mechanism of energy losses due to coupling between the transmission line and steel tubing and casing using resonance mode analysis. The design of a left-handed artificial power line is proposed to minimize the losses due to the right-handed properties of the coaxial transmission line. The design utilizes ideal lumped element method to determine the left-handedness of the right-handed coaxial transmission line over the industrial heating radio-frequency band. The model is developed and simulated using COMSOL multi-physics commercial simulation software. The effect of transmission line position within the annular space on the tangential magnetic field and resulting power losses along the tubing is discussed. It is observed that the resulting artificial power line improves RF power transmission over 60 m depths of the vertical oil well within the industrial heating radiofrequency band.