Start-up of temperature limited heaters using direct current (DC)
AssigneeShell Oil Company
InventorChester Ledlie Sandberg
Life of this patent
Estimating the term…
Abstract
Certain embodiments provide a method for heating a subsurface formation. The method includes applying direct electrical current (DC) to a heater section below a first selected temperature to provide an electrically resistive heat output. The heater section includes one or more electrical conductors electrically coupled to the electrical power supply. The heater section is configured to be placed in an opening in the formation. At least one of the electrical conductors includes ferromagnetic material. Time-varying current is applied to the heater section when a temperature of the heater section approaches or is above the selected temperature. Heat is allowed to transfer from the heater section to a part of the subsurface formation.
Claims21
A method for heating a subsurface formation, comprising:
- applying direct electrical current (DC) to a heater section below a first selected temperature to provide an electrically resistive heat output, the heater section comprising one or more electrical conductors electrically coupled to the electrical power supply and configured to be placed in an opening in the formation, at least one of the electrical conductors comprising ferromagnetic material;
- applying time-varying current to the heater section when a temperature of the heater section approaches or is above the selected temperature;
- and
- allowing the heat to transfer from the heater section to a part of the subsurface formation.
Dependencies are inferred from the claim text.