Artificial maturation of Monterey kerogen (Type II-S) in a closed system and comparison with Type II kerogen: implications on the fate of sulfur

Closed system pyrolysis was performed on a Monterey sulfur-rich kerogen (Type II-S) in the temperature range 300–500°C using varying pyrolysis times. Compared to a typical Type II marine kerogen (Toarcian) the Monterey kerogen decomposes at a faster rate. Significant differences in maturation characteristics of Monterey kerogen are: (1) earlier generation of the C14+ fraction, (2) greater amounts of H2S, and (3) dominant organic sulfur moieties in the pyrolysis extracts (alkylthiophenes). The results show that the rate of generation of alkylthiophenes is higher than the rate of generation of n-alkanes for this sulfur-rich kerogen. The alkylthiophenes may be produced during the pyrolysis of sulfur-rich organic matter.