西湖凹陷南部始新统烃源岩有机质碳同位素组成特征

Characteristics of Carbon Isotopic Composition of the Eocene hydrocarbon source rocks in southern Xihu Depression

随着东海盆地西湖凹陷平湖组和花港组勘探获得重大突破,始新统的勘探潜力也日益受到重视。始新统烃源岩的特征分析是烃源岩潜力研究的重要内容。采用碳同位素分析对烃源岩进行研究。烃源岩有机质碳同位素分析表明,始新统烃源岩有机质除饱和烃碳同位素均值小于-28‰外;芳烃、非烃、沥青质碳同位素值均值均大于-28‰,且平湖组比宝石组碳同位素值增长3‰以上。始新统平湖组和宝石组烃源岩有机质碳同位素组分皆存在δ^13C饱和烃<δ^13C非烃<δ^13C沥青质<δ^13C芳烃和δ^13C饱和烃<δ^13C非烃<δ^13C芳烃<δ^13C沥青质特征,呈现“逆转”现象。西湖凹陷南部始新统烃源岩有机质碳同位素主要受沉积环境和生源母质影响,存在海相陆相混源的特点。

The basement reservoirs are great breakthrough in Pinghu Formation and Huagang Formation,exploration potential of Baoshi Formation that under Pinghu Formation is attached more importance to. The feature analysis of the Eocene hydrocarbon source rocks in southern Xihu Depression is an important task for hydrocarbon source potential research. The analysis of the carbon isotope is used to study hydrocarbon source rocks. Carbon isotope analysis of Pinghu Formation and Baoshi Formation source rocks in southern Xihu Depression shows that the Carbon isotope values of saturated hydrocarbon is less than -28‰,and the Carbon isotope values of aromatic hydrocarbon、Non-hydrocarbon、asphaltene are greater than -28‰,and the Carbon isotope values of Pinghu Formation is more than the Carbon isotope values of Baoshi Formation for 3‰. Carbon isotope values of Pinghu Formation and Baoshi Formation source rocks in southern Xihu Depression shows that saturated hydrocarbon < Non-hydrocarbon < asphaltene < aromatic hydrocarbon and aturated hydrocarbon < Non-hydrocarbon < aromatic hydrocarbon < asphaltene. The carbon isotopes of the Eocene hydrocarbon source rocks in southern Xihu Depression commonly show reverse phenomenon. The carbon isotopes of the Eocene hydrocarbon source rocks in southern Xihu Depression is mainly influenced by sedimentary environment and source rocks and mixed with marine and continental source rocks.