基于化学计量法的渤海海域庙西地区原油类型划分及油源鉴别

Crude oil type classification and source rock identification in Miaoxi area of Bohai Sea area based on stoichiometric method

唐友军 付天意 杨海风 王飞龙 汤国民 孙鹏

TANG Youjun FU Tianyi YANG Haifeng WANG Feilong TANG Guomin SUN Peng

长江大学 资源与环境学院, 武汉 430100 油气资源与勘探技术教育部重点实验室(长江大学), 武汉 430100 中海石油(中国)有限公司 天津分公司, 天津 300459 长江大学 石油工程学院, 武汉 430100

College of Resources and Environment, Yangtze University, Wuhan, Hubei 430100, China Key Laboratory of Exploration Technologies for Oil and Gas Resources of Ministry of Education, Yangtze University, Wuhan, Hubei 430100, China Tianjin Branch of CNOOC (China) Co., Ltd., Tianjin 300459, China College of Petroleum Engineering, Yangtze University, Wuhan, Hubei 430100, China

渤海海域庙西地区原油类型复杂，油源及成因类型不清，多元统计分析可以综合考察多种关联数据间的交叉关系, 尤其适合于大规模数据收集的数据挖掘和区域性的油—油(源)分析。利用生物标志物指标参数体系，采用国际上常用的层次聚类分析(HCA)和主成分分析(PCA)，对渤海海域庙西地区多个层位的原油进行了油—油(源)对比。庙西地区存在3种类型原油：Ⅰ类原油成熟度较低，低的C23TT/C30H比值反映可能源自淡水湖泊，处于还原环境且有充足的陆源有机质输入，其与黄河口东洼沙一、二段烃源岩具有良好的相关性；Ⅱ类原油处于成熟阶段，C23TT/C30H和G/C30H比值低于Ⅰ类原油，但Pr/Ph、甾烷/藿烷、C19TT/C23TT比值略高于Ⅰ类原油，表明原油可能源自淡水湖泊环境，陆源有机质输入，推断其源于沙三段烃源岩，黄河口东洼与庙西南洼烃源岩对Ⅱ类原油均有贡献；Ⅲ类原油处于成熟阶段，ETR[(C28TT+C29TT)/(C28TT+C29TT+Ts)]、G/C30H、C23TT/C21TT、Pr/Ph和C23TT/C30H、C24Te/C26TT、规则甾烷C27/C29、4-甲基甾烷/C29规则甾烷参数分布范围较为广泛，反映出油源岩的沉积环境和有机质输入的类型具有较大的异向性，推断其可能为沙三段、沙四段烃源岩的混源油。利用交替最小二乘法计算显示，Ⅲ类原油主要来源于沙四段烃源岩，贡献率为85%~93%，沙三段的贡献率仅为7%~15%。

The crude oil types in the Miaoxi area of the Bohai Sea area are highly complex, and the source rocks and genetic types remain unclear. Using multivariate statistical analysis, researchers can comprehensively examine the interrelationships among multiple correlated variables, which is particularly suitable for large-scale data mining and regional oil-oil and oil-source analysis. In this study, based on the biomarker parameter index system, hierarchical cluster analysis (HCA) and principal component analysis (PCA), common methods in multivariate statistical analysis, were applied for oil-oil and oil-source correlation of crude oil from multiple layers in the Miaoxi area. Three types of crude oil were detected. Type Ⅰ crude oil are characterized by a low C23TT/C30H ratio with relatively low maturity. It may be derived from a freshwater lacustrine reducing environment with abundant input of terrigenous organic matter. This type of crude oil shows a strong correlation with the source rocks in the first and second members of the Shahejie Formation in the eastern sag of the Huanghekou Depression. Type Ⅱ crude oil is at a mature stage and features lower C23TT/C30H and G/C30H ratios compared to Type Ⅰ, but with slightly higher Pr/Ph, sterane/hopane, and C19TT/C23TT ratios. These features also indicate a freshwater lacustrine environment with terrestrial organic matter input. It is inferred that Type Ⅱ oil is mainly sourced from the third member of the Shahejie Formation, with contributions from source rocks in both the eastern sag of the Huanghekou Depression and the southern sag of the Miaoxi Depression. Type Ⅲ crude oil is at a mature stage, exhibiting a wide distribution range in multiple biomarker parameters, including ETR[(C28TT+C29TT)/(C28TT+C29TT+ Ts)], G/C30H, C23TT/C21TT, Pr/Ph, C23TT/C30H C24Te/C26TT, C27/C29 regular sterane, and 4-methyl sterane/ C29 regular sterane. These variations reflect heterogeneity in the depositional environment of oil source rocks and organic matter types. It can be concluded that type Ⅲ crude oil is mixed-source oil, likely derived from the third and fourth members of the Shahejie Formation. Alternating least squares analysis results indicated that Type Ⅲ crude oil is mainly derived from the source rocks in the fourth member of the Shahejie Formation, with a contribution rate of 85% to 93%, while the contribution from the third member is only 7% to 15%.

国家自然科学基金项目 42202163;国家自然科学基金项目 41972148

https://doi.org/10.11781/sysydz2025040820