ELECTRICALLY ISOLATING INSULATED CONDUCTOR HEATER

摘要

A heating system for a subsurface formation includes an electrical conduc tor and an insulation layer at least partially surrounding the electrical co nductor. A jacket that includes ferromagnetic material at least partially su rrounds the insulation layer. The outside surface of the jacket is configure d to be at little or no electric potential while the electrical conductor is conducting electricity and while the jacket is at temperatures below the Cu rie temperature of the ferromagnetic material.