Thermal processes for subsurface formations

摘要

A subsurface heating system configured to heat a hydrocarbon containing formation is described. The system comprises: a heater well extending from a surface of the earth into the hydrocarbon containing formation; and one or more electrical conductors configured to be placed in the heater well, at least one of the conductors extending from the surface into the hydrocarbon containing formation. At least one electrical conductor has an electrically resistive portion configured to provide a heat output when an alternating current is applied through the electrically resistive portion. At least one of the electrically resistive portions is configured to provide a reduced heat output that is about 20% or less of the heat output provided at about 50° below the selected temperature when above or near a selected temperature. The system is configured to provide heat to the hydrocarbon containing formation such that sufficient heat transfers from at least one of the electrical conductors to hydrocarbons in the hydrocarbon containing formation to at least mobilize some hydrocarbons in the formation.