Microfacies and diagenetic alteration in a semi-deep to deep lacustrine shale: The Yanchang Formation in the Ordos Basin, China  

作　　者：Bin Bai Jing-Yue Hao Ling Fu Yu-Xi Liu Jian-Peng Wang Lan Wang Kevin GTaylor Lin Ma 

机构地区：[1]PetroChina Research Institute of Petroleum Exploration and Development,Beijing,100083,China [2]Department of Earth and Environmental Sciences,University of Manchester,M139PL,UK [3]College of Earth Sciences,Jilin University,Changchun,130061,jilin,China [4]Department of Chemical Engineering,University of Manchester,M139PL,UK

出　　处：《Petroleum Science》2024年第3期1524-1538,共15页石油科学（英文版）

基　　金：founded by National Natural Science Foundation of China(grant Nos.:42072186 and 42090025);National Science and Technology Major Project,China(grant No.:2016ZX05046001);Science and Technology Research Project of Petro China Company Limited,China(grant No.:2021DJ1806);the fund support from China Scholarship Council(No.201806440002);the International Postdoctoral Exchange Fellowship Program,China(Talent-Introduction Program,No.270152);Lin Ma wishes to acknowledge the fund support from Natural Environment Research Council,United Kingdom(NE/R013527/1)。

摘　　要：The mineralogical development and diagenetic sequence of lacustrine shales in the Chang 7 Member of the Yanchang Formation in the Ordos Basin are detailed studied.A model of their depositional system and a diagenetic diagram are proposed in this study.Through detailed petrographic,mineralogical,and elemental analyses,four distinct shale types are identified:argillaceous shale,siliceous shale,calcareous shale,and carbonate,clay,and silt-bearing shale.The main diagenetic process in argillaceous shale is the transformation of illite to smectite,negatively impacting shale porosity.Siliceous shale undergoes carbonate cementation and quartz dissolution,contributing to increased porosity,particularly in mesopores.Calcareous shale experiences diagenesis characterised by carbonate formation and dissolution,with a prevalence of siderite.In carbonate,clay,and silt-bearing shale,the dissolution of K-feldspar contributes to illitization of kaolinite.Argillaceous shale,characterised by more clay minerals and lower mesopore volume,is identified as a potential hydrocarbon seal.Siliceous shale,with the highest pore volume and abundant inter-mineral pores,emerges as a promising shale oil reservoir.These findings contribute to a comprehensive understanding of shale properties,aiding in the prediction of shale oil exploration potential in the studied area.

关 键 词：Ordos Basin Yanchang Formation Chang 7 Member DIAGENESIS MICROFACIES 

分 类 号：P618.13[天文地球—矿床学] TE311[天文地球—地质学]