摘要
页岩中有机质的宏微观赋存特征对于确定其成因、时空分布以及生烃机理等均具有重要的意义,而目前对于不同矿物/岩相与有机质间赋存的非均质性及模式方面的研究较为薄弱。为此,以四川盆地及周缘上奥陶统五峰组—下志留统龙马溪组页岩为研究对象,利用X射线衍射、岩心观察、扫描电镜等手段,分析微米—纳米级尺度下无机矿物成因、形态及其与有机质的接触关系,并在岩相划分的基础上,研究厘米—毫米级尺度下岩相与有机质的赋存关系,探讨有机质成因、宏微观展布及其主控因素。研究结果表明:(1)研究区页岩矿物组分以石英和黏土矿物为主,有机质为可溶有机质和不溶有机质;(2)石英、黏土矿物、碳酸盐矿物存在着3种有机质赋存样式,黄铁矿存在着4种有机质赋存样式;(3)研究区页岩可划分为富有机质硅质页岩、高有机质硅质黏土质页岩、高有机质含灰硅质黏土质页岩和低有机质粉砂黏土质页岩等4种典型岩相;(4)有机质在不同尺度上表现出赋存方式的非均质性,其中富有机质硅质页岩中有机质赋存的非均质性表现在相同或相似沉积环境下纹层内部,低有机质粉砂黏土质页岩中的有机质赋存的非均质性表现在不同沉积环境下形成的纹层间;(5)有机质赋存的主控因素包括有机质类型与演化条件、无机组分成因与形态、沉积环境等。结论认为,不同尺度下有机质赋存的非均质性影响着页岩气"甜点"的分布与预测结果的吻合度。
The Macro–micro occurrence characteristics of organic matters in shale are significant to determine their genesis,space-time distribution and hydrocarbon generation mechanism.At present,however,the heterogeneity and model of occurrence between different mineral/lithofacies and organic matters are rarely researched.In this paper,the shale of Upper Ordovician Wufeng Fm-Lower Silurian Longmaxi Fm in the Sichuan Basin and its peripheral areas was studied.The genesis and form of inorganic minerals in micrometer–nanometer scale and their contact relationships with organic matters were systematically analyzed by using X-ray diffraction,core observation,scanning electron microscopy（SEM） and so on.Then,on the basis of lithofacies division,the occurrence relationship between lithofacies and organic matters in centimeter–millimeter scale was studied and the genesis,macro–micro distribution and main control factors of organic matters were discussed.And the following research results were obtained.First,the mineral compositions of shale in the study area are mainly quartz and clay minerals and the organic matters are divided into soluble organic matter and insoluble organic matter.Second,there are three types of organic matter occurrence patterns in quartz,clay minerals and carbonate minerals,and four types in pyrite.Third,the shale in the study area can be divided into four typical lithofacies,including organic-rich siliceous shale,high total organic siliceous clayey shale,high total organic limy siliceous shale and organic-lean silty–clayey shale.Fourth,the occurrence of organic matters in the different scales is heterogeneous.The heterogeneity of organic-rich siliceous shale is presented in the laminae formed in the same or similar sedimentary environment.The heterogeneity of organic-lean silty–clayey shale is presented between the laminae formed under different sedimentary environments.Fifth,the main factors controlling the occurrence of organic matters include organic matter types and evolution conditions,genesis and morphology of inorganic components,sedimentary environment,etc.In conclusion,the heterogeneous occurrence of organic matters in different scales influences the coincidence of shale gas ＂sweet spots＂ distribution and prediction.
作者
吴靖
胡宗全
谢俊
刘忠宝
赵建华
Wu Jing;Hu Zongquan;Xie Jun;Liu Zhongbao;Zhao Jianhua(College of Earth Science and Engineering,Shandong University of Science and Technology,Qingdao,Shandong 266590,China;Sinopec Petroleum Exploration and Production Research Institute,Beijing 100083,China;Sin-opec Key Laboratory of Shale Oil/Gas Exploration ＆ Development,Beijing 100083,China;School of Geoscience,China University of Petroleum,Qingdao,Shandong 266580,China)
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2018年第8期23-32,共10页
Natural Gas Industry
基金
中国石化科技攻关项目"川东南五峰组-龙马溪组细粒沉积特征研究"(编号:P16043)
关键词
四川盆地及周缘
晚奥陶世
早志留世
页岩
有机质
宏观与微观
赋存机制
岩相/矿物
非均质性
Sichuan Basin and its peripheral areas
Late Ordovician
Early Silurian
Shale
Organic matter
Macroscopic and microscopic
Occurrence mechanism
Lithofacies/mineral
Heterogeneity
