Sulfur aromatic compounds as maturity parameters

Abstract

The main aim of this study was to evaluate how the distribution of sulfur compounds could be applied in correlation studies and as maturity parameters. The work was concentrated on sulfur containing aromatic compounds, using gas chromatography with dual FID/FPD for the detection of aromatic hydrocarbons and sulfur aromatic compounds. Eleven crude oils from North Sea reservoirs were analysed in addition to sediment samples from nine wells in the same area. Five of the wells were chosen in order to be able to follow the maturity related changes for relatively pure type II kerogens, all Upper Jurassic sediments. Apart from some problems that were probably due to contamination from migrated condensate range hydrocarbons, this sample set gave some relatively clear conclusions as to the maturity related changes. The other four weels contained more varied kerogen types, and the conclusions based on these results were less clear. The oil samples could be separated into two groups based on some of the sulfur aromatic ratios, these two groups being the same as previously determined from other parameters such as biomarkers. The variations in the relative distribution of dibenzothiophene (DBT) and methyldibenzothiophenes (MDBT) were seen to be applicable as maturity indicators. Some results obtained on the effect of changes in organic matter type and reported.