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oa Thermal Maturity and Facies Variations Reflected in δ34S Values of Dibenzothiophehes - Case Study from the Eagle Ford Formation
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, IMOG 2025, Sep 2025, Volume 2025, p.1 - 2
Abstract
The variations of d34S values in organosulfur compounds (primarily benzo- and dibenzothiophenes) in naturally occurring oils, with increasing thermal maturation was noted by several studies in the past decade. Previous attempts to utilize the d34S values of dibenzothiophenes showed limited success due to secondary alteration of the oils (e.g. TSR), narrow range of thermal maturities covered and limited understanding of the genetic oils families within a given petroleum system.
In the present study we performed compounds specific sulfur isotopes analysis on a suite Eagle Ford oils and compared the isotopic data to previously published geochemical data and maturation indices for the same oils. These reservoirs were chosen as they share the same source rock, experienced no secondary processes and represent a range of thermal maturity degrees.
Our results demonstrate that variations in d34S values of 4-methyldibenzothiophene can effectively be used as a proxy for thermal maturity in oil samples that originated from a single facies from a given source rock. Our suggested thermal maturity proxy (?34S (4-methyldibenzothiophene – 4,6-dimethyldibenzothiophene)) minimizes the effect of the initial kerogen d34S value and allows thermal maturity comparison of oils generated from different facies of a given source.