鄂尔多斯中部奥陶系水溶烃的分子地球化学特征

Characteristics of Molecular Geochemistry of Ordovician Dissolved Hydrocarbons in the Central Part of Ordos Basin

应用GC、GC/MS分析法 ,系统剖析了鄂尔多斯中部奥陶系马家沟组水溶烃的分子地球化学特征 ,对其生物标志物组成、成熟度和成因进行了研究。研究认为 ,鄂尔多斯中部马家沟组水溶烃系高—过成熟阶段的烃产物 ,主要来源于下古生界海相碳酸盐岩的贡献 ,并且不同井区水溶烃的有机质生源构成和成熟度等存在差异 ,从北 (陕 81井 )到南 (陕 12井 ) ,水溶烃组成中菌藻类低等生源比例增加 。

By using gas chromatography and gas chromatography-mass spectrometry, the characteristics of molecular geochemistry of dissolved hydrocarbons from Ordovician Majiagou Formation in the central part of Ordos Basin have been systemically studied in this paper. The biomarker composition, maturity and origin of these dissolved hydrocarbons have also been discussed. The results demonstrated that dissolved hydrocarbons of Majiagou Formation in the central part of Ordos basin were the product of high mature-overmature thermal evolution stage and mainly derived from lower Palaeozoic marine carbonate source rocks. There were some differences in the organic matter source and maturity of dissolved hydrocarbons of Majiagou Formation from different wells in the central part of Ordos Basin. The contribution of lower Palaeozoic marine carbonate increases with the source of bacteria and algae in Ordovician dissolved hydrocarbons from the northern well (Shan 81) to the southern well (Shan 12).