Patent ID: 8200072

Claim:
A system configured to heat at least a part of a hydrocarbon containing formation, comprising: an opening extending from a surface of the earth into a hydrocarbon containing layer in the formation; an AC power supply; one or more electrical conductors configured to be electrically coupled to the AC power supply and located in the opening and extending from the surface into the hydrocarbon containing layer, wherein at least one of the electrical conductors comprises a heater section at least partially in the hydrocarbon containing layer, the heater section comprising an electrically resistive ferromagnetic material configured to provide an electrically resistive heat output when AC is applied to the ferromagnetic material, and wherein the heater section is configured to provide a reduced amount of heat near or above a selected temperature during use due to the decreasing AC resistance of the heater section when the temperature of the ferromagnetic material is near or above the selected temperature; and wherein the system is configured to allow heat to transfer from the heater section such that heat transfers from the heater section to hydrocarbons in the hydrocarbon containing layer to at least mobilize some hydrocarbons in the layer.