准噶尔盆地东北缘上石炭统巴山组烃源岩沉积环境分析及物源示踪——来自泥岩地球化学的证据

Research on sedimentary environment and provenance for hydrocarbon source rocks of Upper Carboniferous Batamayineishan Formation in northeastern Junggar Basin: evidences from the geochemistry of mudstones

蔡倩茹 王金铎 张关龙 宋智华 王圣柱 熊峥嵘 倪胜利

CAI Qianru WANG Jinduo ZHANG Guanlong SONG Zhihua WANG Shengzhu XIONG Zhengrong NI Shengli

1. 中国石化 胜利油田分公司 勘探开发研究院, 山东 东营 257000; 2. 中国石化 胜利石油管理局 博士后科研工作站, 山东 东营 257000

1. Exploration and Development Research Institute of SINOPEC Shengli Oilfield Branch Company, Dongying, Shandong 257000, China; 2. Postdoctoral Research Workstation of SINOPEC Shengli Petroleum Management Bureau, Dongying, Shandong 257000, China

烃源岩分布规律和生烃潜力是制约准噶尔盆地东北地区油气勘探的关键因素之一，而沉积背景和环境变化是控制烃源岩成因、分布以及有机质类型的主要因素，沉积岩中的主微量元素、稀土元素等在沉积过程中往往受古气候、古水体化学条件、古环境以及古物源的影响。因此，通过对沉积岩中元素分布规律的全面分析，有助于确定沉积环境和演变过程。对准噶尔盆地东北缘富蕴地区上石炭统巴山组暗色泥岩样品的主微量元素、稀土元素进行地球化学特征分析，结合样品的岩石学特征，揭示古沉积环境和物源区构造背景，为烃源岩形成和发育条件提供地质约束。泥岩的化学风化作用指标、元素含量和元素比值的综合分析表明，巴山组沉积期的古气候条件温暖湿润、水体属氧化条件下的半咸水—淡水，且水体较浅、沉积速率相对稳定。主微量元素特征指示母岩类型主要为沉积岩和长英质火山岩，物源来自卡拉麦里岛弧酸性火成岩区的风化产物，反映了后碰撞阶段由挤压向伸展的构造转变。沉积环境和构造背景控制陆源高等植物输入增多，烃源岩有机质丰度中等，具有一定的生烃潜力。

The distribution rules and hydrocarbon potential of source rocks are the major factors which determine oil and gas exploration in the northeastern Junggar Basin. Sedimentary background and environmental changes are the main factors controlling the genesis, distribution, and organic matter types of hydrocarbon source rocks. The main and trace elements and rare earth elements in sedimentary rocks are often influenced by palaeoclimate, paleo water chemical conditions, palaeoenvironment, and palaeosource during sedimentation process. Therefore, a comprehensive analysis of the distribution patterns of elements in sedimentary rocks can help to determine sedimentary environment and evolution process. The geochemical characteristics of major and trace elements and rare earth elements for mudstones of the Upper Carboniferous Batamayineishan Formation from outcrops of the north- eastern Junggar Basin were studied to reveal the sedimentary environment and the tectonic setting of the provenance, which can provide geological constraints for the origin and development conditions of hydrocarbon source rocks. According to a comprehensive analysis on chemical weathering indicators, element contents, and ratios between various major and trace elements, the mudstones of Batamayineishan Formation were deposited in a warm and humid paleoclimate background, and the deposition process was relatively stable in a shallow water with brackish-fresh features under oxidizing environment. Major and trace elements of mudstones indicate that the parent rocks are sedimentary rocks and felsic volcanic rocks and their provenance is derived from the weathering products of acidic igneous rocks of the Karamaili Island Arc, reflecting the tectonic transition from compression to extension during the post collision stage. The depositional environment and tectonic setting controlled the increased input of terrestrial higher plants, resulting in the medium abundance of organic matter with good hydrocarbon generating potential.

中国石化科技攻关项目(P21077-1)和中国石化胜利油田博士后项目(YKB2301)联合资助。

https://doi.org/10.11781/sysydz202401146