Study on oil-source correlation by analyzing organic geochemistry characteristics： a case study of the Upper Triassic Yanchang Formation in the south of Ordos Basin, China

• Published in: 中国地球化学学报：英文版 Vol. 35; no. 4; pp. 408 - 420
• Main Author: Delu Li Rongxi Li Baoping Wang Zhi Liu Xiaoli Wu Futian Liu Bangsheng Zhao Jinghua Cheng Wenbin Kang
• Format: Journal Article
• Language: English
• Published: 2016
• Subjects: 三叠系延长组; 上三叠统延长组; 有机地球化学; 气相色谱-质谱法; 氧化还原环境; 油源分析; 特征对比; 鄂尔多斯盆地南部
• ISSN: 1000-9426; 1993-0364

In the south of the Ordos Basin, the oil source of the Upper Triassic Yanchang Formation is confused all the time, which affects further exploration. In this study, oil sources from the oil layers of Ch6, Ch8 and Ch9 are all analyzed and confirmed. Through their carbon isotope value and biomarkers, characteristics of crude oils from the Yanchang Formation are analyzed. Then, the oil-source relation is discussed, with the source rocks＇ features. Finally, the oil-source relation is calculated through cluster analysis. It is believed that the oils from the Yanchang Formation deposit in a similar redox environment, with weak oxidation-weak reduction, and have all entered maturity stage. Ch9 crude oil is more mature than crude oils from Ch6 and Ch8, and has more advanced plants and fewer algae. Gas chromatography （GC） and gas chromatography-mass spectrometry （GC-MS） analysis show that crude oils from Ch6 and Ch8 may come from Ch7, and Ch9 crude oil may not. Cluster analysis displays that crude oils from Ch6 and Ch8 have closer squared Euclidean distance with Ch7 source rocks than Ch9 crude oil does, indicating crude oils from Ch6 and Ch8 stem from Ch7 source rocks. And Ch9 crude oil has rather close squared Euclidean distance with Ch9 source rocks, illustrating Ch9 crude oil may be from Ch9 source rocks. This research may provide the theoretical basis for the next exploration deploy in the south of Ordos Basin.