Yields of H2S and gaseous hydrocarbons in gold tube experiments simulating thermochemical sulfate reduction reactions between MgSO4 and petroleum fractions

The addition of MgSO4·7H2O, TSR can significantly enhance the yield of methane, also reflected in an increase in its δ13C value. Besides methane, the other gaseous hydrocarbons (C2, C3) in the MgSO4·7H2O series also showed some less negative δ13C values relative to the blank series, irrespective of the fraction type. Relative to the other fractions (saturated, polar and asphaltene), low yields of C1-C5 gaseous hydrocarbons derived from the aromatic fraction could be attributed to the greater stability of the benzene ring and indicate that paraffinic oils may be more susceptible to thermal or thermochemical alterations than aromatic oils under the conditions of real subsurface reservoirs.