TECHNOLOGY FOCUS - MECHANICAL ENGINEERING - Preferred Method: One or more heat sources (801) comprise at least two heat sources, and superposition of heat from at least two heat sources pyrolyzes at least some hydrocarbons within the selected section of the formation. Controlling formation conditions comprises maintaining a temperature within the selected section within a pyrolysis temperature range. The method further comprises controlling pressure and temperature within at least a majority of the selected section of the formation, where the pressure is controlled as a function of temperature, or vice versa. It further comprises controlling a pressure within at least a majority of the selected section of the formation with a valve coupled to at least one of the heat sources, or coupled to a production well in the formation. It further comprises controlling the heat such that an average heating rate of the selected section is less than 1degreesC/day during pyrolysis. Providing heat from one or more heat sources to at least a portion of formation comprises heating a selected volume (V) of the hydrocarbon containing formation from one or more heat sources where the formation ha an average heat capacity (Cv), and where the heating pyrolyzes at least some hydrocarbons within the selected volume of the formation. Heating energy/day provided to the volume is equal to or less than Pwr, where Pwr = hasteriskVasteriskCvasteriskapproximatelyr-B, where Pwr is the heating energy/day; h is an average heating rate of the formation; and rho-B is formation bulk density. The heating rate is less than 10degreesC/day, allowing heat to transfer from heat source(s) to the selected section comprises transferring heat by conduction. Providing heat from heat source(s) comprises heating the selected section such that a thermal conductivity of at least a portion of the selected section is greater than 0.5 W/(m degreesC). The method further comprises controlling a pressure at least 2 bar absolute within at least a majority of the selected section of the formation. It further comprises controlling formation conditions such that the produced mixture comprises a partial pressure of H2 within the mixture greater than 0.5 bar. The partial pressure of H2 is measured when the mixture is at a production well. Controlling formation conditions comprises recirculating a portion of hydrogen from the mixture into the formation. The method further comprises altering a pressure within the formation to inhibit production of hydrocarbons from the formation having carbon numbers greater than 25. It further comprises providing hydrogen (H2) to the heated section to hydrogenate hydrocarbons within the section; and heating a portion of the section with heat from hydrogenation. It further comprises separating the produced mixture into a gas stream and a liquid stream and separating the liquid stream into an aqueous stream and a non-aqueous stream. The mixture product comprises hydrogen sulfide (H2S), or carbon dioxide (CO2), the method further comprises separating the H2S or CO2 from the non-condensable hydrocarbons. The method may comprise providing heat from heat source(s) to at least a portion of the formation; allowing heat to transfer from heat source(s) to a selected section of the formation to raise an average temperature within selected section to, or above a temperature that will pyrolyze hydrocarbons within selected section; producing a mixture from the formation; and controlling API gravity of the produced mixture to be greater than 25degrees API by controlling average pressure and average temperature in the selected section such that the average pressure in the selected section is greater than the pressure (p) in equation (I), p = (-44000divideT+67)log10, where p is in psi and T is in degreesK, or controlling a weight percentage of olefins of the produced mixture to be less than 20 wt.% by controlling average pressure and average temperature in the selected section such that average pressure in the selected section is greater than the pressure (p) in equation (II) for an assessed average temperature (T) in the selected section, where p = (-57000divideT+83)log10, or controlling hydrocarbons having carbon numbers greater than 25 of the produced mixture to be less than 25 wt.% by controlling average pressure and average temperature in the selected section such that the average pressure in the selected section is greater than the pressure (p) in equation (III), p = (-14000divideT+25)log 10, or controlling an atomic hydrogen to carbon ratio of the produced mixture to be greater than 1.7 by controlling average pressure and average temperature in the selected section such that the average pressure in the selected section is greater than the pressure (p) in equation (IV), p = (-38000divideT+61)log10, where p is in psi and T in degreesK. It may comprise providing heat to at least a portion of a hydrocarbon containing formation such that temperature (T) in a part of the heated portion exceeds 270degreesC and hydrocarbons are pyrolyzed within the heated portion of the formation; controlling pressure (p) within at least a part of the heated portion of the formation, where Pbar is greater than ((-A/F)+B-26744)log10, where p is pressure in bar absolute, T is in degreesK, A and B are parameters that are larger than 10 and are selected in relation to the characteristics and composition of the hydrocarbon containing formation and on the required olefin content and carbon number of the pyrolyzed hydrocarbon fluids; and producing pyrolyzed hydrocarbon fluids from the heated portion of the formation.Preferred Components: Heat source(s) comprise electrical heaters (803), surface burners, flameless distributed combustors, or natural distributed combustors. The well bore of the production well (825) comprises a heater to heat the formation with the heater to produce the mixture comprising a large non-condensable hydrocarbon gas component and H2.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The produced mixture comprises condensable hydrocarbons having an American Petroleum Institute (API) gravity of at least 25degrees. Preferred Composition: The produced mixture comprises condensable hydrocarbons, and 0.1-15 wt.% of the condensable or non-condensable hydrocarbons are olefins. It also comprises non-condensable hydrocarbons, and a molar ratio of ethene to ethane in the non-condensable hydrocarbons is 0.001-0.15. It comprises condensable hydrocarbons, and less than 1 wt.%, when calculated on an atomic basis, of the condensable hydrocarbons is nitrogen, oxygen, or sulfur, 5-30 wt.% of the condensable hydrocarbons comprise oxygen containing compounds comprising phenols, greater than 20 wt.% of the condensable hydrocarbons are aromatic compounds, less than 5 wt.% of the condensable hydrocarbons comprise multi-ring aromatics with more than two rings, less than 0.3 wt.% of the condensable hydrocarbons are asphaltenes, or 5-30 wt.% of the condensable hydrocarbons are cycloalkanes.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The non-condensable component comprises hydrogen at greater than 10 vol.% or less than 80 vol.% of the non-condensable component. The produced mixture comprises ammonia, which is used to produce fertilizer, and greater than 0.05 wt.% of the produced mixture is ammonia.