Effects of source facies and maturity on individual carbon isotopic compositions of oil  

作　　者：Jingkun Zhang Jian Cao Baoli Xiang 

机构地区：[1]State Key Laboratory of Palaeobiology and Stratigraphy,Nanjing Institute of Geology and Palaeontology,Chinese Academy of Sciences,Nanjing 210008,China [2]MOE Key Laboratory of Surficial Geochemistry,School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023,China [3]Research Institute of Experiment and Testing,PetroChina Xinjiang Oilfield Company,Karamay,Xinjiang 834000,China

出　　处：《Geoscience Frontiers》2024年第5期210-221,共12页地学前缘（英文版）

基　　金：funded by the National Natural Science Foundation of China(Grants No.42102148 and 42230808).

摘　　要：Carbon isotopes have been used extensively in tracing the sources of oil.However,primary source facies and secondary alteration controls on oil isotopic compositions have not been well resolved,resulting in application uncertainties.A case study was undertaken for an alkaline lacustrine oil system in a lower Permian formation in the Junggar Basin,NW China.Results indicate that increasing maturity causes the carbon isotopic composition to become heavier for only short–middle-chain compounds,whereas source facies-related carbon assimilation controls the compositions of short-,middle-,and long-chain compounds.In particular,light-carbon assimilation during organic-matter degradation makes the isotopic composition lighter,whereas heavy carbon from the water mass makes it heavier.Accordingly,oils in this study area were divided into Type U and Type N oils based on individual compound carbon isotopic compositions,reflecting the difference in source facies in a highly saline and reducing stratified water environment.The results provide a better understanding of the controls on carbon isotopes in oil in sedimentary basins,reducing the uncertainty in oil–source correlation and addressing the origin of oil.

关 键 词：Carbon assimilation Water stratification Carbon isotopes Alkaline lacustrine Junggar Basin 

分 类 号：P534.53[天文地球—古生物学与地层学]