Patent ID: 7841401

Claim:
A method for treating a subsurface treatment area in a formation, comprising: forming a low temperature barrier around at least a portion of a perimeter of the treatment area; providing heat to the subsurface treatment area in the formation from one or more heaters in the treatment area; introducing a sweep fluid into the formation from a plurality of wells offset from the heaters and between the low temperature barrier and the heaters in the treatment area to inhibit outward migration of formation fluid from the treatment area; and providing additional heat to at least a portion of the formation adjacent to at least one well of the plurality of wells, wherein at least one additional heat source is positioned in the well of the plurality of wells, and wherein the heat source is configured to provide the additional heat without raising an average temperature of the portion of the formation above a pyrolysis temperature of hydrocarbons in the formation or a dissociation temperature of nahcolite in the formation.