吉木萨尔凹陷二叠系芦草沟组烃源岩有机岩石学特征及其赋存状态

综合运用岩心观察、薄片鉴定、地球化学参数分析等方法,对准噶尔盆地吉木萨尔凹陷吉32井二叠系芦草沟组烃源岩开展了有机岩石学精细研究。结果表明:综合反射光、透射光特征,烃源岩有机质赋存形式划分为有形态有机质、无形态有机质和次生有机质,有机显微组分划分为5组12组分,以腐泥组无结构藻类体和沥青质体为主,次生组含量普遍较高,镜质组和惰质组含量较低,壳质组含量极少;依据有机质组分荧光性、含量、形态等特征,有机显微组分在岩石矿物中具有5种赋存状态,有机显微组分类型及含量具有显著的非均质性,与所赋存的岩石岩性组分、结构、构造具有明显的对应关系;腐泥组无结构藻类体和无定形体等富氢有机组分与有机碳含量和生烃潜力呈正相关关系,为该区主要的生烃有机组分。

Organic petrology characteristics and occurrence of source rocks in Permian Lucaogou Formation, Jimsar sag

Based on the core observation, thin section authentication and geochemical parameters analysis, the detailed study of organic petrology was conducted for the source rocks from the Permian Lucaogou Formation in Jimsar sag of the Junggar Basin. The modes of occurrence of organic matter in these source rocks were structrurally recognized as structural maceral, amorphous maceral, and secondary maceral with the aid of reflected and transmitted light petrography, the organic macerals mentioned above were divided into five groups (sapropelineie, exinite, vitrinite, inertinite, and secondary maceral) and further twelve sub-fractions, which was dominated by unstructural algae and asphaltene, the content of secondary macerals was generally higher, while the contents of vitrinite and inertinite were relative low and exinite occurred in minute amounts. According to the fluorescence, content and shape of organic maceral, the source rocks show strong heterogeneity in the types and contents of the components with respect to rocks types with various lithologies, textures and sedimentary structures. The total organic carbon contents and hydrocarbon generation potential are strongly correlated with the amount of unstructural algae and amorphous macerals, which suggests that unstructural algae and amorphous macerals are major components for the hydrocarbon generation in the Lucaogou Formation.