A process may include providing heat from one or more heaters to at least a portion of a subsurface formation. Heat may transfer from one or more heaters to a part of a formation. In some embodiments, heat from the one or more heat sources may pyrolyze at least some hydrocarbons in a part of a subsurface...http://www.google.ca/patents/US7640980?utm_source=gb-gplus-sharePatent US7640980 - Thermal processes for subsurface formations
