Abstract: A heater system may include an alternating current supply and an electrical conductor. An alternating current may be applied to one or more electrical conductors at a voltage above about 200 volts. The electrical conductors may be located in a formation. The electrical conductors may provide an electrically resistive heat output upon application of the alternating electrical current. At least one of the electrical conductors may include an electrically resistive ferromagnetic material. An electrical conductor may provide a reduced amount of heat above or near a selected temperature. Heat may be allowed to transfer from an electrical conductor to a part of the formation.

Abstract: A heater may include an electrical conductor. Applying alternating current to the electrical conductor may resistively heat the electrical conductor. The electrical conductor may include an electrically resistive ferromagnetic material. The ferromagnetic material may at least partially surround a non-ferromagnetic material. The heater may provide a reduced amount of heat above or near a selected temperature. An electrical insulator may at least partially surround the electrical conductor. A sheath may at least partially surround the electrical insulator.

Abstract: A heater system may include an alternating current supply and an electrical conductor. Alternating current may be applied to one or more electrical conductors at a frequency between about 100 Hz and about 1000 Hz. The electrical conductors may be located in a formation. The electrical conductors may resistively heat upon application of the alternating electrical current. At least one of the electrical conductors may include an electrically resistive ferromagnetic material. The electrical conductor may provide a reduced amount of heat above or near a selected temperature. Heat may transfer from the electrical conductor to a part of formation.

Abstract: Systems and methods are described for heating a subsurface formation. Alternating electrical current may be applied to one or more electrical conductors. The electrical conductors may be located in a subsurface formation. The electrical conductors may provide an electrically resistive heat output upon application of the alternating electrical current. At least one of the electrical conductors may include an electrically resistive ferromagnetic material. The electrical conductor may provide a reduced amount of heat above or near a selected temperature. Heat may be allowed to transfer from the electrical conductor to a part of the subsurface formation.

Abstract: A process may include providing heat from one or more heaters to at least a portion of a subsurface formation. Heat may transfer from one or more heaters to a part of a formation. In some embodiments, heat from the one or more heat sources may pyrolyze at least some hydrocarbons in a part of a subsurface formation. Hydrocarbons and/or other products may be produced from a subsurface formation. Certain embodiments describe apparatus, methods, and/or processes used in treating a subsurface or hydrocarbon containing formation.

Abstract: A heater may include an electrical conductor. Applying alternating current to the electrical conductor may generate resistively heat the electrical conductor. The electrical conductor may include an electrically resistive ferromagnetic material. The ferromagnetic material may at least partially surround a non-ferromagnetic material. The heater may provide a reduced amount of heat above or near a selected temperature. A conduit may at least partially surround the electrical conductor. A centralizer may maintain a separation distance between the electrical conductor and the conduit.

Abstract: An oil shale formation may be treated using an in situ thermal process. Hydrocarbons, H2, and/or other formation fluids may be produced from the formation. Heat may be applied to the formation from one or more heat sources to raise a temperature of a portion of the formation to a desired temperature. Some of the heat sources may be conductors placed within conduits. The conductors may be resistively heated so that the conductors radiantly heat the conduits. The generated heat may transfer to the formation.

Abstract: An oil shale formation may be treated using an in situ thermal process. Hydrocarbons, H2, and/or other formation fluids may be produced from the formation. Heat may be applied to the formation from one or more heat sources to raise a temperature of a portion of the formation to a desired temperature. Some of the heat sources may be conductors placed within conduits. The conductors may be resistively heated so that the conductors radiantly heat the conduits. The generated heat may transfer to the formation.

Abstract: A heater may include an electrical conductor. Applying alternating current to the electrical conductor may generate resistively heat the electrical conductor. The electrical conductor may include an electrically resistive ferromagnetic material. The ferromagnetic material may at least partially surround a non-ferromagnetic material. The heater may provide a reduced amount of heat above or near a selected temperature. A conduit may at least partially surround the electrical conductor. A centralizer may maintain a separation distance between the electrical conductor and the conduit.

Abstract: A hydrocarbon containing formation may be treated using an in situ thermal process. Hydrocarbons, H2, and/or other formation fluids may be produced from the formation. Heat may be applied to the formation from heat sources to raise a temperature of a portion of the formation to a desired temperature. Some of the heat sources may include heater elements. The heater elements may be lengths of bare metal disposed within wellbores within the formation.

Abstract: A hydrocarbon containing formation may be treated using an in situ thermal process. Hydrocarbons, H2, and/or other formation fluids may be produced from the formation. Heat may be applied to the formation from heat sources to raise a temperature of a portion of the formation to a desired temperature. Some of the heat sources may be conductors placed within conduits. The conductors may be resistively heated so that the conductors radiantly heat the conduits. The conduits may transfer heat to the formation.

Abstract: Systems and methods are described for heating a subsurface formation. Alternating electrical current may be applied to one or more electrical conductors. The electrical conductors may be located in a subsurface formation. The electrical conductors may provide an electrically resistive heat output upon application of the alternating electrical current. At least one of the electrical conductors may include an electrically resistive ferromagnetic material. The electrical conductor may provide a reduced amount of heat above or near a selected temperature. Heat may be allowed to transfer from the electrical conductor to a part of the subsurface formation.

Abstract: A heater system may include an alternating current supply and an electrical conductor. An alternating current may be applied to one or more electrical conductors at a voltage above about 200 volts. The electrical conductors may be located in a formation. The electrical conductors may provide an electrically resistive heat output upon application of the alternating electrical current. At least one of the electrical conductors may include an electrically resistive ferromagnetic material. An electrical conductor may provide a reduced amount of heat above or near a selected temperature. Heat may be allowed to transfer from an electrical conductor to a part of the formation.

Abstract: A heater may include an electrical conductor. Applying alternating current to the electrical conductor may resistively heat the electrical conductor. The electrical conductor may include an electrically resistive ferromagnetic material. The ferromagnetic material may at least partially surround a non-ferromagnetic material. The heater may provide a reduced amount of heat above or near a selected temperature. An electrical insulator may at least partially surround the electrical conductor. A sheath may at least partially surround the electrical insulator.

Abstract: An oil shale formation may be treated using an in situ thermal process. Heat may be applied to the formation from one or more heat sources to raise a temperature of a portion of the formation to a desired temperature. Hydrocarbons, H2, and/or other formation fluids may be produced from the formation. Some or all of the sources may be removable from the formation during and/or after use.

Abstract: A hydrocarbon containing formation may be treated using an in situ thermal process. Hydrocarbons, H2, and/or other formation fluids may be produced from the formation. Heat may be applied to the formation from heat sources to raise a temperature of a portion of the formation to a desired temperature. Some of the heat sources may include heater elements. The heater elements may be lengths of bare metal disposed within wellbores within the formation.

Abstract: A hydrocarbon containing formation may be treated using an in situ thermal process. Hydrocarbons, H2, and/or other formation fluids may be produced from the formation. Heat may be applied to the formation from heat sources to raise a temperature of a portion of the formation to a desired temperature. Some of the heat sources may be insulated conductors, such as mineral insulated cables. The insulated conductors may provide radiant heat to a portion of the formation.

Abstract: A hydrocarbon containing formation may be treated using an in situ thermal process. Hydrocarbons, H2, and/or other formation fluids may be produced from the formation. Heat may be applied to the formation from heat sources to raise a temperature of a portion of the formation to a desired temperature. Some of the heat sources may be conductors placed within conduits. The conductors may be resistively heated so that the conductors radiantly heat the conduits. The conduits may transfer heat to the formation.