塔里木盆地典型来自于寒武系－下奥陶统烃源岩原油的同位素组成特征及其成因探讨

近年来在塔里木盆地发现典型来自于寒武系－下奥陶统烃源岩的原油具有富集13C的特征、其全油稳定碳同位素比值基本上集中在－28‰左右，比来自于中上奥陶统烃源岩的原油偏重3－6‰；同时原油与其母质干酪根之间稳定碳同位素分布存在倒转的特征。本工作结合塔里木盆地海相油气藏勘探研究活动中的最新问题发现，研究目标针对典型源自寒武系－下奥陶统烃源岩的原油富集13C的同位素分布特征入手，综合运用有机岩石学、有机地球化学和古生物地球化学等研究手段深入研究原油及其与烃源岩母质干酪根和无机碳酸盐稳定同位素之间的协同演化成因机制、探讨原油与母质干酪根之间稳定碳同位素倒转现象发生的制约因素。结合塔里木盆地两套海相主力烃源岩发育的具体地质演化背景，分析这些典型源自寒武系－下奥陶统烃源岩的原油富集13C同位素特征在盆地内海相油藏中的代表性，并尝试在此基础上探讨两套海相主力烃源岩针对塔里木盆地海相油藏的相对贡献。

The oils, recently found sourced from the Cambrian-Lower Ordovician strata rocks in the Tarim Basin, NW China, were characterized by enrichment in 13C, with the values of bulk oils around -28‰, which were typically heavier than those oils sourced from the Middle-Upper Ordovician strata by 3-6‰. The reversal stable carbon isotopic patterns were found between the 13C enriched oils and their mother kerogens. Based on the most recently results from the Tarim Basin, this work is aimed to probe the 13C enriched oils comprehensively by the methods of organic petrology, organic geochemistry and paleo-biogeochemistry, to investigate the synchronous variations of the stable isotopes between the oils, their mother kerogens and the inorganic minerals, and then to make the diagnostic analyses of the reversal carbon isotopic patterns between the 13C enriched oils and the kerogens. Combined with the geological background settings of the two sets of main source rocks for the marine crude oils in the Tarim Basin, whether or not the 13C enriched crude oils bear the representative nature will be scrutinized throughout the basin, and then to evaluate the relative contributions of each set of source rocks to the extensive occurring marine crude oils in the Tarim Basin, NW China.