Flash pyrolysis of artificially matured kerogens from the Kimmeridge Clay, U.K.

Abstract

Laboratory heating of an immature Kimmeridge kerogen (type II) at different temperatures under conditions reported to approximate to natural maturation, produced a series of kerogen residues which were characterised by flash pyrolysis gas chromatography (PY-GC) and PY-GC-mass spectrometry. The residues showed trends which were similar to those reported in natural burial sequences—for example an increase in the aliphatic nature of the pyrolysates with increased temperature or time. However, quantitative PY-GC proved that the proportion of kerogen represented by the pyrolysate decreased with increasing maturation. An examination of the sulphur-containing components of the pyrolysates revealed a sharp decrease in some compounds with increasing maturation temperature. This was illustrated by the rapid disappearance of 2-methylthiophene relative to toluene. At the highest maturation temperatures an increase in the proportion of benzothiophene relative to alkylated benzothiphenes was observed. The significance of these trends is discussed.