alternating electric current from the power source on the ground level delivered for example through wireline 34 is made to flow through the coil which produces an oscillating magnetic field which creates heat in the base pipe in two different ways principally it induces an electric current in the base pipe which produces resistive heating proportional to the square of the current and to the electrical resistance of the pipe secondly it also creates magnetic hysteresis losses in the base pipe due to its ferromagnetic nature the first effect dominates as hysteresis losses typically account for less than ten percent of the total heat generated induction heaters are faster and more energy efficient than other electrical heating devices moreover they allow for instant control of heating energy since the induction heaters are more efficient when in the close proximity to the base pipe it is suggested that the copper wire coils are mounted on an expandable toward the pipe wall wire line tool activated when it reaches the level of the packer or the screen if the mandrel 1 is dielectric then the full effect of the heater 32 will go into the ferromagnetic particles 30 that are embedded in the element 2 and locally heat the element 2 from within preferably the particles will be randomly distributed throughout the element 2 so that the.