Maturity and depositional controls on compound-specific sulfur isotope values of saline lacustrine source rocks in the north Dongpu Depression, Bohai Bay Basin

Ke, Changwei ¹Li, Sumei ¹Greenwood, Paul ²He, Nannan ²Grice, Kliti ²Xu, Tianwu ³Zhang, Hanjing¹

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作者信息

1. China Univ Petr
2. Curtin Univ
3. SINPEC Zhongyuan Oilfield Co
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Abstract

Source rocks and oil sands from the northern Dongpu Depression have been analyzed by gas chromatography multicollector inductively coupled plasma mass spectrometry (GC-MC-ICP MS) to investigate the compound-specific sulfur isotope (delta S-34) values of saline lacustrine source rocks. The samples were also subject to more traditional organic geochemical analyses including hydrocarbon biomarker detection by gas chromatography/mass spectrometry (GC/MS), carbon and oxygen isotopic analysis by isotope ratio mass spectrometer, and major and trace inorganic element analysis. delta S-34(OSCs) values measured for a limited number of organic sulfur compounds (OSCs) showed a quite large range (5.16 parts per thousand-44.73 parts per thousand). The source rocks and oil sands could be separated into two groups with delta S-34 values above or below 25.00 parts per thousand. The first group with delta S-34 25.00 parts per thousand, were primarily the Weicheng source rocks, which also typically showed an increase in delta S-34 values with increasing alkylation. The second group had delta S-34 < 25.00, the delta S-34 of dibenzothiophenes showed a positive correlation with the concentration of the saturated hydrocarbon fraction of rocks, and a negative correlation with the polar (resin + asphaltene) fraction. The delta S-34(OSCs) show obvious positive correlation with gammacerane/C-31 hopane and C-35/C-34 hopanes and excellent correlation with contents of minerals and ratios of trace elements, reflecting a S-34 enrichment in closed evaporative environment (conducive to the sulfurisation of organic matter) and relative S-34 depletion in terrestrial environments. These trends identify the depositional environment of the source rocks as one of controls on delta S-34(OSCs) values. Thermal maturity was also observed to influence delta S-34(OSCs) values, becoming heavier with increasing maturity. There was a good result of oil-source rock correlation by delta(SOSC)-S-34 in this study. This study demonstrates the contribution delta S-34(OSCs) data can make to oil-oil and oil-source rock correlations as well as providing further evidence of their sensitivity to depositional environments and thermal maturity.

Key words

Dongpu depression/Saline lacustrine/Isotopes of organic sulfur compounds/Major and trace elements/Maturity/Depositional environment/THERMOCHEMICAL SULFATE REDUCTION/ORGANOSULFUR COMPOUNDS/THERMAL MATURATION/SHAHEJIE FORMATION/ALBERTA BASIN/OILS/SEDIMENTARY/EXPLORATION/RESERVOIR/HISTORY

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出版年

2022

Journal of Petroleum Science & Engineering

ISSN：0920-4105

被引量4

参考文献量60

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