NOVELTY - Treatment of hydrocarbon containing formation in situ, involves supplying heat from one or more heat sources to portion(s) of the formation, transferring heat from sources to selected section of formation, controlling heat from the sources such that average temperature within at least majority of the selected section of the formation is less than 375 degrees C, and producing a mixture from formation.    USE - For production of synthesis gas used for synthesizing organic and/or inorganic compounds such as hydrocarbon and ammonia, for generating electricity by combustion as a fuel, reducing the pressure of synthesis gas in turbines and/or using the temperature of synthesis gas to make steel, for energy generation unit such as molten carbonate fuel cell, solid oxide fuel cell or other type of fuel cell, for paraffins production, for production of methanol, gasoline, diesel fuel, ammonia and middle distillates.    ADVANTAGE - Spacing between the heat sources is selected to increase effectiveness of heat sources, thereby increasing economic viability of selected in situ conversion process for hydrocarbons. The superposition of heat tends to increase the uniformity of heat distribution in the section of formation selected for treatment. The heating of hydrocarbon containing formation is accomplished in an economical way. Fewer heat sources are sufficient to heat greater portion of the formation. The system configured for heating formation has longer life time. The pyrolysis of the portion by superposition of heat produces relatively high, uniform permeability through the portion, which allows for generation of synthesis gas from a significant portion of the formation at relatively low pressures. The relatively high and uniform permeability result in relatively high recovery efficiency of synthesis gas as compared to synthesis gas generation in hydrocarbon containing formation that has not been treated. Electrical energy costs associated with heating at least a portion of the formation with an electric heater is reduced and a more economical process is provided for heating the hydrocarbon containing formation. Increasing the formation pressure to increase the amount of pyrolyzation fluids in the vapor phase permits increased recovery of lighter and high quality pyrolyzation fluids. Carbon dioxide produced from the formation is used for feedstock for production of urea and/or may be reinjected into hydrocarbon containing formation for synthesis gas production and/or coal bed methane production. An oxidizing fluid is used to inhibit carbon deposition. High quality hydrogen, hydrocarbon and other products are produced.    DETAILED DESCRIPTION - Heat from one or more heat sources is transferred to selected section of formation, heat is controlled so that average temperature within at least majority of selected section is less than 375 degrees C, at least some hydrocarbons within selected section is pyrolyzed and a mixture is produced. The selected section is heated so that thermal conductivity of portion(s) of selected section is greater than about 0.5 W/(m degrees C).    INDEPENDENT CLAIMS are included for the following:    (1) In situ method for heating hydrocarbon containing formation;    (2) In situ method for producing hydrogen from hydrocarbon containing formation;    (3) Formation of heater wells in hydrocarbon containing formation;    (4) System configured to heat hydrocarbon containing formation;    (5) Mixture produced from a portion of hydrocarbon containing formation;    (6) In situ production of synthesis gas from hydrocarbon containing formation;    (7) Method of forming spent portion of formation from hydrocarbon containing formation;    (8) Sequestering method of carbon dioxide within hydrocarbon containing formation;    (9) In situ production of energy from hydrocarbon containing formation; and    (10) Production of ammonia using carbon containing formation.