Patent ID: 8238730
Filing Date: 2012-08-07
Classification: E21B,H05B

Abstract:
1. A system configured to heat a hydrocarbon containing formation, comprising: a heater well extending from a surface of the earth through an overburden of the formation and into a hydrocarbon containing layer in the formation; an AC supply configured to provide AC at a voltage above about 200 volts; and one or more electrical conductors located in the heater well and extending from the surface into the hydrocarbon containing layer, the electrical conductors being electrically coupled to the AC supply; at least one electrical conductor comprising one or more ferromagnetic sections, and being configured to provide an electrically resistive heat output during application of AC to the electrical conductor such that heat transfers from the electrical conductor to hydrocarbons in the hydrocarbon containing layer to at least mobilize some hydrocarbons in the layer; wherein one or more of the ferromagnetic sections provides a reduced amount of heat above or near a selected temperature during use, wherein the selected temperature is at or about the Curie temperature of the ferromagnetic section.