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

Abstract

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 C 14+ fraction, (2) greater amounts of H 2S, 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.