Patent ID: 6948563

Claim:
A method of treating a hydrocarbon containing formation in situ, comprising: providing heat from one or more heaters positioned in heater wells to at least a section of the formation; allowing the heat to transfer from the one or more heaters to a part of the formation; wherein the part of the formation has been selected for heating using an atomic hydrogen weight percentage of at least a portion of hydrocarbons in the part of the formation, and wherein at least the portion of the hydrocarbons in the part of the formation comprises an atomic hydrogen weight percentage, when measured on a dry, ash-free basis, of greater than about 4.0%; pyrolyzing hydrocarbons in the part of the formation; controlling the heat such that an average heating rate of the part of the formation is less than about 1° C. per day in a pyrolysis temperature range of about 270° C. to about 400° C.; and producing a mixture from the formation.