TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Conditions: The formation conditions are controlled by maintaining temperature of the selected section within pyrolyzes temperature range. The pressure and temperature are controlled within the selected section of formation, where the pressure is controlled as function of temperature and the temperature is controlled as function of pressure. The pressure is controlled with a valve coupled to heat source(s) or production well located in the formation. The heating is controlled so that average heating rate of selected section, is less than 1 degrees C/day during pyrolyzes. The selected section of formation is heated, such that thermal conductivity of at least a portion of selected section is greater than 0.5 W/(m degrees C). The selected volume (V) of the hydrocarbon containing formation is heated from heat source(s), such that the formation has average heat capacity (Cv), where heating pyrolyzes at least some hydrocarbons within the selected volume of formation and heating energy per day provided to the volume is equal to or less than Pwr (power). Pwr is calculated from the following equation: Pwr = hxVxCvxrhoB, where h is average heating rate of formation (less than 10 degrees C per day) and rhoB is formation bulk density. The pressure is controlled within selected section of the formation to 2 bar or more. The produced mixture has a partial pressure of hydrogen of greater than 0.5, measured when the mixture is at a production well. The controlling formation conditions comprises recirculating a portion of hydrogen from the mixture into the formation.Preferred Heater: The heat source(s) comprise at least two heat sources and superposition of heat from at least two sources pyrolyzes at least some hydrocarbons within the selected section of the formation. The heat sources comprise electrical heaters (803), surface burners, flameless distributed combustors or natural distributed combustors.Preferred Composition: The produced mixture comprises condensable hydrocarbons having American petroleum institute (API) gravity of 25 degrees or more, and non-condensable hydrocarbons. 0.1-15 weight% (wt.%) of each of condensable hydrocarbon and non-condensable hydrocarbon is olefins. The molar ratio of ethene to ethane in the non-condensable hydrocarbon is 0.001-0.15. Less than 1 wt.% of condensable hydrocarbons calculated on atomic basis, is nitrogen, sulfur or oxygen. 5-30 wt.% of condensable hydrocarbon comprise oxygen containing compounds such as phenols. Less than 5 wt.% of condensable hydrocarbons comprise multi-ring aromatics. The non-condensable component comprises 10-80 volume% of hydrogen. The mixture comprises 0.05 wt.% of ammonia which is used to produce fertilizer.