A system for heating a subsurface formation is described. The system includes a plurality of elongated heaters located in a plurality of openings in the formation. At least two of the heaters are substantially parallel to each other for at least a portion of the lengths of the heaters. At least two of...http://www.google.ca/patents/US8027571?utm_source=gb-gplus-sharePatent US8027571 - In situ conversion process systems utilizing wellbores in at least two regions of a formation
