川东北地区二叠系烃源岩沉积环境及控制因素——以城口木瓜口剖面为例

Sedimentary environments and controlling factors of Permian source rocks in northeastern Sichuan Basin：A case study of Muguakou profile in Chengkou

彭金宁 张敏 刘光祥 潘文蕾

Peng Jinning Zhang Min Liu Guangxiang Pan Wenlei

长江大学 地球环境与水资源学院, 武汉 430100 2. 中国石油化工股份有限公司 石油勘探开发研究院 无锡石油地质研究所, 江苏 无锡 214126

Department of Geochemistry, Yangtze University, Wuhan, Hubei 430100 2. Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214126, China

基于前人研究资料和野外露头剖面详细观测及样品实测数据，以川东北城口木瓜口二叠系剖面为例，通过常量元素（氧化物）、微量元素等参数进行古环境条件恢复，分析了古环境与烃源岩发育的相关性，并探讨了烃源岩纵横向分布的主控因素。研究认为：（1）在横向上，研究区二叠系深水陆棚相、台盆相烃源岩最发育，有机质丰度也相对高，台内洼地亚相烃源岩丰度较低；（2）在纵向上，二叠系烃源岩主要发育于海侵半旋回中，最大海泛时期烃源岩有机质丰度指标最好；（3）古生物生产力和有机质保存是控制烃源岩有机质丰度的主要因素，并且只有当古生产力高，有机质保存好时，源岩的有机质丰度最好，两者缺一不可。

Based on previous analyses as well as filed outcrop observations and sample tests, a case study of the Permian profile in the Chengkou area of the northeastern Sichuan Basin was carried out. Palaeoenvironment was restored according to the parameters of macroelement (oxidizing material) and microelement, and the relationship between palaeoenvironment and source rock development was analyzed. The controlling factors for the vertical and horizontal distributions of source rock were discussed. Several conclusions were made as followed. 1) On plane map, the source rocks of deepwater marine shelf and interplatform basin facies had the highest organic matter abundance and were most widespread in Permian in the study area. The source rocks of innerplatform depression subfacies had lower organic matter abundance. 2) Vertically, the Permian source rocks mainly developed in transgressive hemicycle, and reached the highest organic matter abundance during the maximum flooding period. 3) Organic matter abundance was controlled by ancient biological productivity and organic matter preservation condition. Both of the 2 factors were necessary for high organic matter abundance.

中国石化科技部项目“四川盆地二叠系烃源岩及其资源潜力研究”（P08065）资助。

https://doi.org/10.11781/sysydz201401095