| 渝东南下志留统龙马溪组页岩岩相特征及其对孔隙结构的控制 |
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| 引用本文： | 李卓,姜振学,唐相路,王朋飞,黄璞,王国臻.渝东南下志留统龙马溪组页岩岩相特征及其对孔隙结构的控制[J].地球科学,2017,42(7):1116-1123. |
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| 作者姓名： | 李卓 姜振学 唐相路 王朋飞 黄璞 王国臻 |
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| 作者单位： | 1.中国石油大学油气资源与探测国家重点实验室, 北京 102249 |
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| 基金项目： | 中国地质调查局项目12120114046201国家自然科学基金项目41502123中国石油大学（北京）科研基金2462013YJRC044 |
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| 摘 要： | 目前对优势页岩岩相的划分尚缺乏明确的标准.另外，合理连接不同孔隙测试方法的结果，实现页岩的全孔径孔隙结构定量化表征，成为现阶段亟待解决的关键问题.基于页岩的有机质丰度和矿物组分建立了岩相划分方案，查明了渝东南下志留统龙马溪组页岩发育硅质页岩、混合质页岩和粘土质页岩3类，根据有机质丰度将每类页岩细分为富、含和贫有机质等共计9种岩相，在此基础上开展了低压N2吸附和高压压汞实验.研究区龙马溪组中富有机质页岩孔径呈现多峰分布特征，主要孔径峰值位于2~3nm、70~90nm和200~300nm，页岩的孔体积主要来源于中孔（2~0nm）和宏孔（>0nm），比表面积主要来自中孔和微孔（ < 2nm）；对于孔体积贡献，微孔最高可占12%，中孔占3%，宏孔占2%.对于孔面积贡献，微孔最高占47%，中孔占7%，宏孔占11%.随着粘土矿物含量升高，在200~400nm范围内孔体积显著升高.中孔和宏孔贡献了超过90%的孔体积，微孔和中孔贡献了超过90%的比表面积.富有机质硅质页岩微孔比例高，对比表面积贡献高，孔体积和比表面积最大，有利于页岩气富集，是最有利的页岩岩相.
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| 关 键 词： | 渝东南 龙马溪组 页岩岩相 硅质页岩 孔隙结构 石油地质 |
| 收稿时间： | 2016-11-08 |
Lithofacies Characteristics and Its Effect on Pore Structure of the Marine Shale in the Low Silurian Longmaxi Formation,Southeastern Chongqing |
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| Abstract: | The favorable facies classification for shale has not been established so far, and it is a key issue in shale gas evaluation to characterize the full scale pore size distribution by reasonable relating of different results. In this study, lithofacies classification is established based on TOC and XRD experiments on cores. There are 9 types of lithofacies, namely the Organic-rich siliceous shale (ORS), Organic-rich mixed shale (ORM), Organic-rich argillaceous shale (ORA), Organic-fair siliceous shale (OMS), Organic-fair mixed shale (OMM), Organic-fair argillaceous shale (OMA), Organic-poor siliceous shale (OPS), Organic-poor mixed shale (OPM), and Organic-poor argillaceous shale (OPA) develop in southeastern Chongqing. Low pressure nitrogen adsorption and high pressure mercury intrusion experiments are conducted to quantitatively characterize the full scale pore size distribution. It is found that spectrum of pore size distribution for ORS have multiple peaks at 2-3nm, 70-90nm and 200-300nm, and the peak shifts to the small pore size when the TOC value increases. Mesopores and macropores have the largest proportion in pore volumes, whereas mesopores and micropores take the largest part of the pore surface areas. The pore volume percentage of micropore, mesopore and marcropore is 12%, 53%, and 52% respectively, and the pore surface area percentage of micro pore, mesopore and marcropore is 47%, 57%, and 11% respectively. The volume of 200-400nm pore obviously increases when clay mineral content increases. The contribution to the surface area is over 90% for micropores and mesopores. The contribution to the pore volume is over 90% for mesopores and marcropores. The organic-rich siliceous shale, which has the largest pore volume and surface area, is the most favourable lithofacies for shale gas enrichment. |
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