Theoretical Analysis And Experimental Study Of Underground Electromagnetic Induction Heaters

Traditional ground steam-injected type heavy oil exploitation technology is featured with large heat loss,low energy efficiency and large occupying area,which cause low composite economic results.The disadvantages of electromagnetic induction heating technology provide potentials for usage of downhole heater to exploit heavy oil.Thus,the theoretical analysis and experimental study of downhole electromagnetic induction heater were conducted in this text,and the feasibility of promoting heavy oil exploitation technology by using downhole heater was researched.Aim at the demand of heavy oil heating and viscosity reducing technique,downhole electromagnetic induction heating principle has been set forth,the influences of such factors as the distribution of heating magnetic field,magnet exciting coil and heating element on the heating results of downhole heater have been analyzed and the computational formula derivation of the power of downhole heater has been completed.Combining downhole environment,downhole heater with length of 1000mm,diameter of 70mm and flow diameter of 34mm has been designed.The confirmation of inner parameters of the heater such as the material,thread pitch,wall thickness,winding radius and height of induction coil,and the material,wall thickness,radius and length of heating element and inter-layer material have been completed.When excitation frequency is 10 kHz,the heating power of this heater can theoretically reach 23.04kW.The expansion and efficiency increase plan for heater's power has been put forward from the angle of heating element and heat exchange switching surface in this research.Multi-physics field simulation software COMSOL Multiphysics has been used to establish modules to simulate for heaters,the influences of exciting current and exciting frequency on the distribution of heating magnetic field,temperature field and eddy current field have been analyzed.Simulation results show that when exciting frequency is 10 kHz,the inner walls temperature of heating element of the heater can reach to 220 ?;Increasing heater's length can markedly improve heating results.The reasonability of theoretic calculation and structural design of the heater has been verified by setting up experimental platform,and experimental results show that the measured heating power of designed downhole electromagnetic induction heater can reach 20 kW,with heating efficiency around 90%;Steam production of the heater at temperature of 105? is 163.43kg/h.By adopting technological means of combination of theory,simulation and experiment in this paper,fundamental theoretical analysis and experimental study of downhole electromagnetic induction heater have been completed.The results achieved in this paper play certain theoretical supporting and technical guidance role for the engineering application of downhole electromagnetic induction heater in the course of heavy oil thermal recovery.