下扬子地区幕府山组陆缘海-台地黑色细粒沉积岩系沉积学和孔隙结构特征  

Sedimentology and Porosity Structures of the Epicontinental Sea-PlatformFine-Grained Deposits of Mufushan Formation in Lower Yangtze Area

作　　者：张玉玺[1,2,3] 周江羽[1] 陈建文 张银国[2,3] 张悦[1] 刘甜怡 万雪芳[1] Zhang Yuxi;Zhou Jiangyu;Chen Jianwen;Zhang Yinguo;Zhang Yue;Liu Tianyi;Wan Xuefang(Key Laboratory of Tectonics and Petroleum Resources,Ministry of Education,School of Earth Resources,China University of Geosciences,Wuhan 430074,China;Qingdao Institute of Marine Geology,CGS,Qingdao 266071,China;Key Laboratory of Marine Hydrocarbon Resources and Environmental Geology,Qingdao 266071,China)

机构地区：[1]中国地质大学资源学院,构造与油气资源教育部重点实验室,湖北武汉430074 [2]中国地质调查局青岛海洋地质研究所,山东青岛266071 [3]海洋国家实验室海洋矿产资源评价与探测技术功能实验室,山东青岛266071

出　　处：《地球科学》2021年第1期186-199,共14页Earth Science

基　　金：中国地质调查局“南黄海油气地质调查”专项(No.DD20180152);国家自然科学基金项目(Nos.49972026,41372112,41572109).

摘　　要：黑色细粒沉积岩系沉积学和孔隙结构研究对于沉积环境恢复、页岩气储层评价和有利储层预测具有重要意义.利用下扬子地区最新完钻的XYZ⁃1钻井资料,综合钻井岩心、岩石薄片、XRD分析、氩离子−场扫描电镜等手段,开展幕府山组细粒沉积岩系的沉积学和孔隙结构研究.结果表明,幕府山组岩性组成以块状、纹层状深色(碳质)泥岩、浅灰色纹层状泥质灰岩、泥晶灰岩为主,夹泥灰岩、云灰岩、陆屑灰岩和白云岩、安山岩、角砾岩等,以含硅质粘土质混合页岩相和含硅质粘土质页岩相为主,属于下扬子海盆的陆架浅海碳酸盐岩台地−深水海湾−潮坪环境.幕府山组黑色细粒沉积岩孔隙类型多样,有机孔为2~200 nm,面孔率为2.86%~15.90%,孔隙分布较均匀,但总体连通性较差,部分与脆性矿物或粘土矿物共生的有机孔分布不均匀.无机孔以粒内孔、粒间孔、溶蚀孔为主,部分为晶间孔和矿物层间孔.除黄铁矿晶间孔外,大部分无机孔均大于2μm,最大可达50μm.细粒沉积岩中的微裂缝广泛发育,构造微裂缝形态复杂,缝宽一般20~500μm,常常被方解石和石英充填.成岩微裂缝长度一般大10μm,缝宽50~200 nm.幕府山组顶部深水海湾相和底部泥坪−蒸发台地相黑色细粒沉积岩TOC含量为2.66%~21.27%,平均值为6.30%,有机孔、无机孔和微裂缝发育,粘土矿物和脆性矿物含量较高,具备优质页岩气储层发育的有利条件.The study of sedimentology and pore structure of black fine⁃grained sedimentary rock series is of great significance for environment,shale gas reservoir evaluation and favorable reservoir prediction.Using the newly drilled XYZ⁃1 well data in the Lower Yangtze area,based on systematic coring identification of Lower Cambrian Mufushan Formation,rock thin section,XRD(X⁃Ray Diffraction)analysis,and argon ion⁃field emission⁃scanning electron microscopy(Ar⁃FE⁃SEM),the sedimentology and pore structures of the fine⁃grained deposits series arestudied in this study.The results show that the lithologic composition of the Mufushan Formation is dominated by dark(carbonaceous)mudstone,light gray argillaceous limestone and cryptite,interbeded with marl,dolomitic limestone,terrigenouslimestone and dolomite,Andesite,breccia,etc.,mainly composed of siliceous clay⁃mixed shale facies and siliceous clay⁃like shale facies.It is belong to the continental shelfshallow⁃sea carbonate platform⁃deep⁃water bay⁃tidal flat environment of the lower Yangtze ocean basin.The black argillutite(mud shale)of the Mufushan Formation has various pore types,the organic pores are 2−200 nm,the surface porosity ratio is 2.86%⁃15.90%,the pore distribution is relatively uniform,but the overall connectivity is poor,and some organic pores are inhomogeneity symbiotic with the brittle mineral or clay mineral.The inorganic pores are mainly intragranular,intergranular pores and dissolution pores,and some are intercrystalline pores and intermetallic pores.Except for the intercrystalline pores of pyrite,most of the inorganic pores are larger than 2μm and the maximum is 50μm.The micro⁃cracks in the shale are widely developed,and the micro⁃cracks of tectonic origin are complex in shape,and the slit width is generally 20⁃500μm,generally filled with calcite and quartz.The length of diagenetic micro⁃cracks is generally greater than 10μm and the slit width is 50 to 200 nm.The black mud shale in the upper deep⁃water bay facies an

关 键 词：细粒沉积岩系 沉积充填序列 沉积环境 孔隙结构 幕府山组 下扬子 

分 类 号：P168.13[天文地球—天文学] P581[天文地球—岩石学]