Abstract: An insulated electrical conductor (MI cable) may include an inner electrical conductor, an electrical insulator at least partially surrounding the electrical conductor, and an outer electrical conductor at least partially surrounding the electrical insulator. The insulated electrical conductor may have a substantially continuous length of at least about 100 m. The insulated electrical conductor may have an initial breakdown voltage, over a substantially continuous length of at least about 100 m, of at least about 60 volts per mil of the electrical insulator thickness (about 2400 volts per mm of the electrical insulator thickness) at about 1300° F. (about 700° C.) and about 60 Hz. The insulated electrical conductor may be capable of being coiled around a radius of about 100 times a diameter of the insulated electrical conductor. The outer electrical conductor may have a yield strength based on a 0.2% offset of about 100 kpsi.

Abstract: A method for forming an insulated conductor heater with a final cross-sectional area includes reducing a cross-sectional area of an insulated conductor assembly to form an insulated conductor heater with a final cross-sectional area. The insulated conductor assembly may have been previously treated with at least one combination of a cold working step and a heat treating step. Reducing the cross-sectional area of the insulated conductor assembly to form the insulated conductor heater with the final cross-sectional area may include cold working the insulated conductor assembly to further reduce the cross-sectional area of the insulated conductor assembly by at most about 20% of the cross-sectional area of the insulated conductor assembly after the at least one combination of the cold working step and the heat treating step has been completed.

Abstract: A method for forming an insulated conductor heater includes placing an insulation layer over at least part of an elongated, cylindrical inner electrical conductor, placing an elongated, cylindrical outer electrical conductor over at least part of the insulation layer to form the insulated conductor heater; and performing one or more cold working/heat treating steps on the insulated conductor heater, reducing the cross-sectional area of the insulated conductor heater by at most about 20% to a final cross-sectional area. The cold working/heat treating steps include cold working the insulated conductor heater to reduce a cross-sectional area of the insulated conductor heater; and heat treating the insulated conductor heater at a temperature of at least about 870° C. The insulation layer includes one or more blocks of insulation.

Abstract: A method for accommodating thermal expansion of a heater in a formation includes flowing a heat transfer fluid through a conduit to provide heat to the formation and providing substantially constant tension to an end portion of the conduit that extends outside the formation. At least a portion of the end portion of the conduit is wound around a movable wheel used to apply tension to the conduit.

Abstract: A method for forming an insulated conductor heater includes placing an insulation layer over at least part of an elongated, cylindrical inner electrical conductor. An elongated, cylindrical outer electrical conductor is placed over at least part of the insulation layer to form the insulated conductor heater. One or more cold working/heat treating steps are performed on the insulated conductor heater. The cold working/heat treating steps include: cold working the insulated conductor heater to reduce a cross-sectional area of the insulated conductor heater by at least about 30% and heat treating the insulated conductor heater at a temperature of at least about 870° C. The cross-sectional area of the insulated conductor heater is then reduced by an amount ranging between about 5% and about 20% to a final cross-sectional area.

Abstract: An insulated electrical conductor (MI cable) may include an inner electrical conductor, an electrical insulator at least partially surrounding the electrical conductor, and an outer electrical conductor at least partially surrounding the electrical insulator. The insulated electrical conductor may have a substantially continuous length of at least about 100 m. The insulated electrical conductor may have an initial breakdown voltage, over a substantially continuous length of at least about 100 m, of at least about 60 volts per mil of the electrical insulator thickness (about 2400 volts per mm of the electrical insulator thickness) at about 1300° F. (about 700° C.) and about 60 Hz. The insulated electrical conductor may be capable of being coiled around a radius of about 100 times a diameter of the insulated electrical conductor. The outer electrical conductor may have a yield strength based on a 0.2% offset of about 100 kpsi.

Abstract: A method includes coupling a core of a heating section to a core of an overburden section of an insulated conductor. A diameter of the core of the heating section is less than a diameter of the core of the overburden section. A first insulation layer is placed over the core of the heating section such that at least part of an end portion of the core of the heating section is exposed. A second insulation layer is placed over the core of the overburden section such that the second insulation layer extends over the exposed portion of the core of the heating section. A thickness of the second insulation layer is less than a thickness of the first insulation layer and an outer diameter of the overburden section is substantially the same as an outer diameter of the heating section.

Abstract: An insulated conductor heater may include an electrical conductor that produces heat when an electrical current is provided to the electrical conductor. An electrical insulator at least partially surrounds the electrical conductor. The electrical insulator comprises a resistivity that remains substantially constant, or increases, over time when the electrical conductor produces heat. An outer electrical conductor at least partially surrounds the electrical insulator.

Abstract: A method for forming an insulated conductor heater includes placing an insulation layer over at least part of an elongated, cylindrical inner electrical conductor, placing an elongated, cylindrical outer electrical conductor over at least part of the insulation layer to form the insulated conductor heater; and performing one or more cold working/heat treating steps on the insulated conductor heater, reducing the cross-sectional area of the insulated conductor heater by at most about 20% to a final cross-sectional area. The cold working/heat treating steps include cold working the insulated conductor heater to reduce a cross-sectional area of the insulated conductor heater; and heat treating the insulated conductor heater at a temperature of at least about 870° C. The insulation layer includes one or more blocks of insulation.

Abstract: An insulated conductor heater may include an electrical conductor that produces heat when an electrical current is provided to the electrical conductor. An electrical insulator at least partially surrounds the electrical conductor. The electrical insulator comprises a resistivity that remains substantially constant, or increases, over time when the electrical conductor produces heat. An outer electrical conductor at least partially surrounds the electrical insulator.

Abstract: An insulated conductor heater may include an electrical conductor that produces heat when an electrical current is provided to the electrical conductor. An electrical insulator at least partially surrounds the electrical conductor. The electrical insulator comprises a resistivity that remains substantially constant, or increases, over time when the electrical conductor produces heat. An outer electrical conductor at least partially surrounds the electrical insulator.

Abstract: An insulated conductor heater may include an electrical conductor that produces heat when an electrical current is provided to the electrical conductor. An electrical insulator at least partially surrounds the electrical conductor. The electrical insulator comprises a resistivity that remains substantially constant, or increases, over time when the electrical conductor produces heat. An outer electrical conductor at least partially surrounds the electrical insulator.