Biological origin and depositional environment of crude oils in the Qiongdongnan Basin:Insights from molecular biomarkers and whole oil carbon isotope

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外文摘要：Molecular biomarker and whole oil carbon isotope(δ13Coil)analyses were conducted on eleven typical crude oils from the Qiongdongnan Basin to investigate their biological sources and depositional envi-ronments.Saturated hydrocarbon biomarkers in most samples are characterized by angiosperm-derived compounds,with aromatic compounds dominated by the naphthalene,phenanthrene,biphenyl,and fluorene series.The related source rocks of these oils were mainly deposited under oxic condition,but a subanoxic-suboxic and enclosed water column condition in the Central Depression during Oligocene.The identification of simonellite and related compounds in the aromatic fractions provides reliable ev-idence for the input of coniferous gymnosperms.Cadalene may also have a potential association with gymnosperms since it shows a strong positive correlation with simonellite.Evidence from density,n-alkanes,short-chain alkylbenzenes and secondary brine inclusions indicates that the unique crude oil B13-1 may have suffered from thermal alteration.These crude oils(excluding B13-1)can be classified into four types based on the δ13Coil values and molecular biomarkers.Type A oil(solely S34-3)is char-acterized by non-angiosperm plants,with minor dinoflagellates and increasing contribution from conifer gymnosperms than others.Type B oils(L17-2,L18-1,L25-1,and L25-1W)show heavy δ13Coil(-24 ‰to-25 ‰)and mixed contributions from both angiosperms and marine algae,with the marine algae contribution increasing.Type C oils(L13-2 and B21-1)share similar biological sources with Type B,but the moderately δ13Coil(-25‰ to-26‰)and high level of terrestrial biomarkers suggesting a pre-dominant contribution of angiosperms.Type D oils(Y13-1a,Y13-1b,and Y13-4)possess the lightestδ13Coil(mainly below-26‰)and are primarily derived from angiosperms,with mangrove vegetation playing an important role.Spearman correlation analysis among 14 source biomarker parameters withδ13Coil and geological setting of related source rocks implied that the marine algae should be responsible for the heavy δ13Coil in the Type B.The contribution of marine algae in the Central Depression may have been neglected in the past,as it is usually covered by remarkable angiosperm biomarkers.

外文关键词：

Gas chromatography-mass spectrometryMolecular biomarkerSimonelliteBiological sourceDepositional environment

作者：

Zi-Ming Zhang、Du-Jie Hou、Xiong Cheng、Da-Ye Chen、Gang Liang、Xia-Ze Yan、Wei-He Chen

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作者单位：

School of Energy Resources,China University of Geosciences,Beijing 100083,China

Key Laboratory of Marine Reservoir Evolution and Hydrocarbon Accumulation Mechanism,Ministry of Education,Beijing 100083,China

Beijing Key Laboratory of Unconventional Natural Gas Geological Evaluation and Development Engineering,Beijing100083,China

School of Energy Resources,China University of Geosciences,Beijing,100083,China

Key Laboratory of Marine Reservoir Evolution and Hydrocarbon Accumulation Mechanism,Ministry of Education,Beijing,100083,China

Beijing Key Laboratory of Unconventional Natural Gas Geological Evaluation and Development Engineering,Beijing,100083,China

China Coal Research Institute,Beijing 100013,China

Exploration and Development Resource Institute,Hainan Branch of China National Offshore Oil Corporation,Haikou,570300,Hainan,China

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出版年：

2024

DOI：

10.1016/j.petsci.2024.05.026

石油科学(英文版)

中国石油大学（北京）

石油科学(英文版)

影响因子：0.88

ISSN：1672-5107

年,卷(期)：2024.21(5)