塔西南山前南缘甫沙8井原油与二叠系普司格组烃源岩的地球化学亲缘关系

Geochemical oil and source correlation between crude oil of well Fusha 8 and source rocks of Permian Pusige Formation in southern margin, piedmont of southwestern Tarim Basin

王祥 葛祝时 张慧芳 孙迪 王张虎 谢小敏 孟强 陈果 肖七林

WANG Xiang GE Zhushi ZHANG Huifang SUN Di WANG Zhanghu XIE Xiaomin MENG Qiang CHEN Guo XIAO Qilin

1. 中国石油 塔里木油田分公司, 新疆 库尔勒 841000; 2. 中国石油天然气集团有限公司天然气成藏与开发重点实验室, 河北 廊坊 065007; 3. 新疆超深油气重点实验室, 新疆 库尔勒 841000; 4. 中国石油天然气集团有限公司碳酸盐岩储层重点实验室, 新疆 库尔勒 841000; 5. 长江大学 资源与环境学院, 武汉 430100; 6. 国家能源碳酸盐岩油气重点实验室, 新疆 库尔勒 841000

1. PetroChina Tarim Oilfield Company, CNPC, Korla, Xinjiang 841000, China; 2. Key Laboratory of Gas Reservoir Formation and Development, CNPC, Langfang, Hebei 065007, China; 3. Xinjiang Key Laboratory of Ultra-deep Oil and Gas, Korla, Xinjiang 841000, China; 4. Key Laboratory of Carbonate, CNPC, Korla, Xinjiang 841000, China; 5. College of Resources and Environment, Yangtze University, Wuhan, Hubei 430100, China; 6. State Energy Key Laboratory of Carbonate Oil and Gas, Korla, Xinjiang 841000, China

为进一步拓展塔西南山前南缘油气勘探领域，以该区甫沙克里阳构造带甫沙2井、阳1井二叠系普司格组烃源岩和新发现井——甫沙8井原油为主要研究对象，开展了有机地球化学亲缘关系研究。通过岩石热解、镜质体反射率测试、气相色谱、气相色谱—质谱、正构烷烃单体烃同位素分析，从烃源岩基础地球化学性质、分子标志化合物和单体烃碳同位素组成等方面刻画普司格组不同层段源岩地球化学特征，揭示不同层段烃源岩生烃潜力的差异性，初步探讨甫沙8井原油的来源。研究区普司格组上段上部和中段有机质丰度较低，为Ⅲ型有机质，难以作为有效源岩，同时可能存在深部运移烃侵染；普司格组上段下部和下段有机质丰度相对较高，为Ⅱ1—Ⅲ型有机质，处于低熟—成熟阶段。普司格组上段下部沉积于偏氧化的浅湖环境，有机质为陆源高等植物和水生生物混合来源；下段沉积于还原性较强的深湖—半深湖环境，水生生物贡献相对较高。甫沙8井下侏罗统产出原油的Pr/Ph、C24Te/C26TT和甾烷/藿烷比值较高，C19-C23TT/C30H比值较低，相对富含C29规则甾烷、芴和氧芴，正构烷烃单体碳同位素值介于-32.0‰～-29.0‰之间，这与普司格组上段下部源岩生物标志化合物和单体烃碳同位素组成相一致，证实两者具有较好的亲缘关系。

To further expand the oil and gas exploration in the southern margin of the piedmont of the southwestern Tarim Basin, this study focuses on the newly discovered oil from well Fusha 8 and source rocks from wells Fusha 2 and Yang 1 in the Permian Pusige Formation of the Fusha-Keliyang structural belt. Organic geochemical oil and source correlation research was conducted. Through pyrolysis, vitrinite reflectance testing, gas chromatography (GC), GC-Mass Spectrometry (MS), and n-alkane monomer hydrocarbon isotope analysis, the geochemical characteristics of different layers of source rocks in the Permian Pusige Formation were characterized from aspects such as basic geochemical properties, molecular biomarkers, and monomer hydrocarbon carbon isotope compositions. The study revealed variations in hydrocarbon generation potential across different layers of source rocks from the Pusige Formation. Also, oil sources in well Fusha 8 were preliminarily explored. Results showed that the upper part of the upper section and the middle section of the Pusige Formation had low organic matter abundance, containing type Ⅲ organic matter, and were unlikely to serve as effective source rocks. Also, these source rocks may be contaminated by migrated hydrocarbons from the deeply buried reservoirs. The lower part of the upper section and lower section of the Pusige Formation had relatively higher organic matter abundance, featuring type Ⅱ1 to Ⅲ organic matter in the low mature to mature stages. The lower part of the upper section of the Pusige Formation was deposited in a mildly oxidizing shallow lake environment, and the organic matter inputs were mixtures of terrestrial higher plants and aquatic organisms. Its lower section was deposited in a more reducing deep to semi-deep lake environment, with a higher content of aquatic organisms as inputs. The crude oil from the Lower Jurassic of well Fusha 8 had higher Pr/Ph, C24Te/C26TT, and sterane/hopane ratios and lower C19-C23TT/C30H ratios. It was rich in C29 regular steranes, fluorene, and dibenzofuran, with n-alkane monomer carbon isotope values ranging from -32.0‰ to -29.0‰. These characteristics are consistent with the biomarker and monomer hydrocarbon carbon isotope compositions of the lower part of the upper section of source rocks in the Pusige Formation, confirming a strong geochemical oil and source correlation between them.

国家自然科学基金项目(42073066)和中国石油科技专项子课题(2023ZZ14YJ01)联合资助。

https://doi.org/10.11781/sysydz2025020372