四川盆地及周缘地区龙马溪组页岩微观孔隙结构及其发育主控因素

摘要/Abstract

摘要： 以四川盆地及周缘地区下志留统龙马溪组富有机质页岩为研究对象，通过氩离子抛光—扫描电镜、低温液氮吸附/脱附实验等方法和技术，对研究区页岩储层微观孔隙结构进行系统研究，并探讨了控制纳米尺度微观孔隙结构的主要原因。结果表明：四川盆地及周缘地区龙马溪组富有机质页岩孔径范围为纳米级，孔隙类型多样，分为有机孔、粒间孔、粒内孔、晶间孔、溶蚀孔及微裂缝等，其中有机孔和粒内孔较为发育；页岩微观孔隙结构复杂，多为开放型孔隙，以管孔和两端开口的平行板孔为主；微观孔隙孔径主要分布在2～80nm，以中孔为主。通过分析控制该区页岩储层微观孔隙结构的主要因素，认为有机碳含量是控制纳米级孔隙发育的主要因素，同时也是页岩气赋存的重要物质基础。

关键词: 龙马溪组；四川盆地周缘；纳米级孔隙结构；液氮吸附/脱附；氩离子抛光&mdash, 扫描电镜

Abstract: Microscopic pore structure of the Lower Silurian Longmaxi Formation organic matter-rich shale in the Sichuan Basin and its periphery was systematically studied by using argon-ion polishing-scanning electron microscope (SEM), low-temperature liquid nitrogen adsorption/desorption and other techniques and methods. Moreover, the main factors controlling the nano-scale microscopic pore structure were discussed. The results indicate that pores in the Longmaxi Formation organic matter-rich shale in the Sichuan Basin and its periphery are in nano-scale with diverse types, such as organic matter pore, intergranular pore, intragranular pore, intercrystal pore, dissolved pore, and micro-fractures. The organic matter pore and intergranular pore are better developed. The complex microscopic pore structure of the shale is mostly composed of open pores, including cylinder pores and parallel slate pores with open ends. The radius of microscopic pores are typically 2-80 nm, suggesting as medium pores. Analysis reveals that organic carbon content is the major factor controlling the development of nano-scale pores and the important material basis for the occurrence of shale gas.

Key words: Longmaxi Formation, the Sichuan Basin and its periphery, nano-scale pore structure, nitrogen adsorption/desorption, argon-ion polishing-scanning electron microscope (SEM)

尉鹏飞, 张金川, 隆帅, 彭建龙, 邓恩德, 吕艳南, 马玉龙. 四川盆地及周缘地区龙马溪组页岩微观孔隙结构及其发育主控因素[J]. 中国石油勘探, 2016, 21(5): 42-51.

Wei Pengfei, Zhang Jinchuan, Long Shuai, Peng Jianlong, Deng Ende, L?Yannan, Ma Yulong. Characteristics and controlling factors of microscopic pore structure of Longmaxi Formation in Sichuan Basin and its periphery[J]. China Petroleum Exploration, 2016, 21(5): 42-51.

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