准噶尔盆地玛湖凹陷风城组泥页岩生物标志化合物特征与赋存状态研究

Characteristics and occurrence states of shale biomarker compounds in Fengcheng Formation, Mahu Sag, Junggar Basin

支东明 冷筠滢 谢安 唐勇 何晋译 何文军 李志明 邹阳 朱涛

ZHI Dongming LENG Junying XIE An TANG Yong HE Jinyi HE Wenjun LI Zhiming ZOU Yang ZHU Tao

1. 怀柔实验室新疆研究院, 乌鲁木齐 830000; 2. 中国石化 石油勘探开发研究院 无锡石油地质研究所, 江苏 无锡 214126; 3. 中国石油 新疆油田分公司 勘探开发研究院, 新疆 克拉玛依 834000

1. Xinjiang Research Institute of Huairou Laboratory, Urumqi, Xinjiang 830000, China; 2. Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214126, China; 3. Research Institute of Petroleum Exploration and Development, Xinjiang Oilfield Company, PetroChina, Karamay, Xinjiang 834000, China

准噶尔盆地玛湖凹陷二叠系风城组泥页岩不同层段生物标志化合物特征与赋存状态特征认识较为薄弱，通过采用岩石热解、气相色谱—质谱、荧光薄片和氩离子抛光电镜等实验技术，厘清不同层段烃源岩物质基础、生物标志化合物分布特征及意义、不同赋存状态页岩油，对玛湖凹陷下一步勘探部署具有重要意义。玛湖凹陷风城组泥页岩主要为中等—好烃源岩，有机质类型为Ⅱ型，处于成熟演化阶段；生物标志化合物组成特征表明具有高丰度的Pr和Ph、β-胡萝卜烷及C29重排甾烷，C27-C28-C29规则甾烷呈反“L”型分布，指示有机质以藻类等低等水生生物贡献为主；较低的Pr/Ph比值以及较高的伽马蜡烷指数，反映出沉积环境主要为咸化的还原环境；C31αβ22S/(22S＋22R)、C29M/C29H和C29ββ/(ββ+αα)等藿烷类和甾烷类成熟度参数表明烃源岩处于成熟阶段。另外，风城组二段泥页岩相对于风一段、风三段具有更大的生烃潜力，具备更好的烃源岩物质基础，同时C20/C23TT、C21/C23TT、Ga/C30H等生物标志化合物相关参数指示风二段藻类等贡献较多，更偏还原和咸化的环境；结合风二段以游离赋存状态为主，认为烃类赋存于粒间孔和粒内孔中。风二段有利于页岩油富集与保存，展现出更好的页岩油勘探开发前景。

The characteristics of biomarker compounds and their occurrence states in different layers of the Permian Fengcheng Formation shale in Mahu Sag, Junggar Basin are poorly understood. By using experimental techniques such as rock pyrolysis, gas chromatography-mass spectrometry, fluorescence thin sections, and argon ion polishing electron microscopy, the material basis of hydrocarbon source rocks in different intervals, the distribution characteristics and significance of biomarker compounds, and different occurrence states of shale oil are clarified. This is of great significance for the next step in exploration and deployment in the Mahu Sag. The shale of the Fengcheng Formation in the Mahu Sag is mainly medium to good hydrocarbon source rocks, with type Ⅱ organic matter and in a mature evolutionary stage. The composition characteristics of biomarker compounds show high abundance of Pr and Ph, β-carotane, and C29 rearranged steranes. The C27-C28-C29 regular steranes exhibit an inverted “L” distribution, indicating that the organic matter is mainly contributed by lower aquatic organisms such as algae. Lower Pr/Ph ratios and higher gammacerane indices reflect a saline reducing sedimentary environment. Maturity parameters such as C31αβ22S/(22S+22R), C29M/C29H, and C29ββ/(ββ+αα) for hopanes and steranes indicate that the hydrocarbon source rocks are in the mature stage. In addition, the shale of the second member of the Fengcheng Formation has greater hydrocarbon generation potential and better source rock material basis than that in the first and third members. Meanwhile, biomarker compound parameters such as C20/C23TT, C21/C23TT, and Ga/C30H indicate that the second member has more contributions from algae and other organisms, and a more reducing and saline environment. The hydrocarbons in the second member are mainly in a free occurrence state, residing in intergranular and intragranular pores. The study shows that the second member of the Fengcheng Formation is more favorable for shale oil enrichment and preservation, showing a better prospect for shale oil exploration and development.

新疆维吾尔自治区“天山英才”科技创新领军人才支持项目(2022TSYCLJ0070)和国家自然科学基金项目(42090022)联合资助。

https://doi.org/10.11781/sysydz202405954