Molecular Geochemical Evidence for the Origin of Natural Gas from Dissolved Hydrocarbon in Ordovician Formation Waters in Central Ordos Basin

• Published in: Acta geochimica Vol. 22; no. 3; pp. 193 - 202
• Main Author: 李贤庆 侯读杰 唐友军 胡国艺 熊波
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Nature B.V 2003; Geochemistry Research Center, Jianghan Petroleum University, Jingzhou 434023, China; The State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Wushan, Guangzhou 510640, China%The Department of Energy and Geology, China University of Geosciences, Beijing 100083, China%Geochemistry Research Center, Jianghan Petroleum University, Jingzhou 434023, China%The Laboratory of Natural Gas Geology, Langfang Branch of Research Institute of Petroleum Exploration and Development, Petrochina, Langfang 065007, China
• Subjects: Biomarkers; Carbonates; Dibenzothiophene; Gases; Geochemistry; Geology; Hydrocarbons; Natural gas; Ordos盆地; Ordovician; Organic matter; Ratios; 分子地球化学; 天然气; 奥陶纪; 液化烃; Ordos Basin; China; formation water; Ordos Basin; Ordovician; molecular geochemistry; dissolved hydrocarbon; origin of natural gas
• ISSN: 1000-9426; 2096-0956; 1993-0364; 2365-7499
• DOI: 10.1007/bf02842863

Having studied the biomarker composition and maturity of dissolved hydrocarbons from Ordovician formation waters, the authors presented molecular geochemical evidence for the controversial origin of natural gases in central Ordos Basin. The dissolved hydrocarbons in Well Shah 12 and Well Shan 78 are relatively high in abundance of tricylic terpane, pregnane series and dibenzothiophene series and low in Pr/Ph ( < 2) and hopane/sterane ratios, indicating the source input of marine carbonates. In contrast, the dissolved hydrocarbons in Well Sham 81 are free from tricyclic terpane and pregnane series, with trace dibenzothiophene series and high Pr/Ph (3.27) and higher hopane/sterane ratios, which are the typical features of terrestrial organic matter. Furthermore, Well Shan 37 and Well Shan 34 are between the two situations, having a mixed source of marine carbonate and terrestrial organic matter. The maturity of biomarkers also supports the above suggestions. These results are consistent with the geological background and source rock distribution in this region.