锦州25-1地区烃源岩地球化学特征研究

Geochemical Characteristics of Source Rocks in Jinzhou 25-1 Area

在锦州25-1地区分布三套生油岩系,分别为沙河街组沙三段、沙一段及东营组东三段。此次研究通过对该区多口钻井的三套层系烃源岩进行地球化学特征研究,从有机碳含量、干酪根有机显微组分、镜质体反射率Ro以及生物标志化合物特征等方面,讨论了辽西低凸起三套泥/页岩地球化学特征及生烃潜力。研究认为该区烃源岩有机质丰度高,有机质显微组分显示为含壳质组组分占优势的Ⅱ1型有机质类型,为生烃能力强的油型有机质;该区Es3段烃源岩的成熟度处于成熟~生油高峰阶段,Ed3~Es1烃源岩成熟度处于未成熟阶段,可见该区主力烃源岩为Es3段,次要烃源岩层为Ed3、Es1段;该区生物标志物特征总体上表现为“4-甲基甾烷含量高,甲藻甾烷丰富”,规则甾烷为不对称V型,淡水、富沟鞭藻类沉积有机相,以低等水生生物和藻类占优势,陆源有机质为辅的混合型的母源特征。

Three sets source rocks are distributed in the Jinzhou 25-1 region, namely, the third member of Shahejie formation, the first member of Shahejie Formation and the three member of Dongying formation. This study based on the study of three sets source rocks of the drilling wells from geochemistry, from the aspects of organic carbon content, kerogen macerals, vitrinite reflectance Ro and features of biomarkers, discusses three sets mud/shale geochemical characteristics and hydrocarbon generation potential in Liaoxi low uplift. Study shows that the hydrocarbon source rocks in this region have high abundance of organic matter, organic macerals show II1 type organic matter of containing dominant exinite components , hydrocarbon generation ability for oil type organic matter;the maturity of the source rocks in the Es3 section is in the mature to oil generating peak stage, and the maturity of source rocks in the Ed3 - Es1 is in immature stage, it can be seen that the main source rocks in this area are Es3, and the secondary hydrocarbon source rocks are Ed3 and Es1;the characteristics of biomarkers in this area are characterized by “high content of 4- methyl steroids and abundance of dinoflagellate", the regular steroids are asymmetric V type, and the organic compounds are dominated by fresh water and dinoflagellate, which are dominated by lower aquatic organisms and algae, and are characterized by a mixed source parent.