利用微米X射线显微镜研究陆相延长组页岩孔隙结构特征  

Investigation on Pore Structures of Yanchang Formation Shale Using Micro X-ray Microscopy

作　　者：王羽[1,2] 汪丽华 王建强 王彦飞[4] WANG Yu;WANG Li-hua;WANG Jian-qiang;WANG Yan-fei(Key Laboratory of Interfacial Physics and Technology,Shanghai Institute of Applied Physics,Chinese Academy of Sciences,Shanghai 201800,China;University of Chinese Academy of Sciences,Beijing 100049;Shanghai Synchrotron Radiation Facility,Shanghai Advanced Research Institute,Chinese Academy of Sciences,Shanghai 201204,China;Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China)

机构地区：[1]中国科学院上海应用物理研究所微观界面物理与探测重点实验室,上海201800 [2]中国科学院大学,北京100049 [3]中国科学院上海高等研究院上海同步辐射装置,上海201204 [4]中国科学院地质与地球物理研究所,北京100029

出　　处：《岩矿测试》2020年第4期566-577,共12页Rock and Mineral Analysis

基　　金：国家自然科学基金青年科学基金项目(Y915031031);中国科学院王宽诚率先人才计划“卢嘉锡国际团队”项目(GJTD-2018-10)。

摘　　要：页岩孔隙结构是决定储层储集与运移能力的关键,对完善我国陆相页岩气产能评估方法和压裂技术具有重要意义。本文选取鄂尔多斯盆地陆相延长组7段页岩,利用氩离子抛光-扫描电镜和微米X射线显微镜方法研究其孔隙结构特征与三维空间分布特征。扫描电镜结果表明,延长7段页岩中主要发育粒间孔(300~600nm)和微裂缝,是页岩气的主要储集空间。微裂缝多由黏土矿物沉淀形成,以平直状为主,易引发井壁坍塌等严重问题。有机孔发育较少,一般与有机黏土矿物共存,绝大部分有机质呈致密状。微米X射线显微镜测试进一步表明,长7段页岩在三维空间具有微米级纹层结构,其中有机质纹层厚10~20μm,揭示了延长组7段页岩层具有较强塑性,不利于水平压裂。该研究成果将为构建延长7段页岩气渗流模型、改进压裂技术提供重要数据支持。BACKGROUND:Shale pore structure is the key to determine reservoir storage and migration capacity.It is of great significance for improving the productivity assessment of continental shale gas in China,and fracturing technology.OBJECTIVES:To investigate the pore structure and three dimensional distribution mode of the seventh member of Yanchang Formation shale and its controlling factors.METHODS:Ar-ion milling SEM and synchrotron micro X-ray microscopy were used to characterize the pore structures.RESULTS:The SEM results indicated that the interparticle pores(300-600nm)and micro-fractures were the main reservoir space of the seventh member of Yanchang Formation shale gas.Most of the micro-fractures were formed by the precipitation of clay minerals and presented as a flat shape,which likely caused collapse of borehole walls.Organic pores were less developed and mainly associated with organic clay minerals.The micro X-ray microscopy showed that the seventh member of Yanchang Formation shale had laminated structures at micro-scale with organic matter laminations of 10-20μm in thickness.The results indicated that the seventh member shale had strong plasticity,which was against horizontal fracturing.CONCLUSIONS:The results can provide significant data support for developing a percolation model and improving fracturing technology of shale gas.

关 键 词：微米X射线显微镜 氩离子抛光 微纳孔隙 三维结构 纹层结构 陆相延长组页岩 

分 类 号：P575.5[天文地球—矿物学]