霍健,王星皓,罗超,等. 2021.川南地区龙马溪组页岩储层裂缝特征[J].工程地质学报,29(1):171-182. doi:10.13544/j.cnki.jeg.2020-561. DOI: 10.13544/j.cnki.jeg.2020-561
    引用本文: 霍健,王星皓,罗超,等. 2021.川南地区龙马溪组页岩储层裂缝特征[J].工程地质学报,29(1):171-182. doi:10.13544/j.cnki.jeg.2020-561. DOI: 10.13544/j.cnki.jeg.2020-561
    Huo Jian, Wang Xinghao, Luo Chao, et al. 2021. Fracture characteristics of Longmaxi shale in southern Sichuan[J]. Journal of Engineering Geology, 29(1): 171-182. doi: 10.13544/j.cnki.jeg.2020-561.
    Citation: Huo Jian, Wang Xinghao, Luo Chao, et al. 2021. Fracture characteristics of Longmaxi shale in southern Sichuan[J]. Journal of Engineering Geology, 29(1): 171-182. doi: 10.13544/j.cnki.jeg.2020-561.

    川南地区龙马溪组页岩储层裂缝特征

    FRACTURE CHARACTERISTICS OF LONGMAXI SHALE IN SOUTHERN SICHUAN

    • 摘要: 我国页岩气资源储量巨大,四川盆地更是我国主要的页岩气产区。在页岩气勘探开发中一个重要指标便是裂缝,它承载着气体储存和运输通道两大功能。因此了解储层裂缝的微观性质对于判断储层含气量以及开采远景具有重要意义。本文以页岩气主要产区——川南地区页岩气气田泸201井的岩芯为主要研究对象,以手持显微镜、体式显微镜为主要观察工具,对岩芯进行了细观尺度下的观察,借助于图像软件对岩芯表面进行了图像重构,对储层裂缝的类别及特征、发育特征及矿物特征等进行了统计分析,并成功构建出研究区页岩岩芯二维裂缝模型。通过宏观到微观角度观察研究发现:(1)龙马溪组龙一1亚段1、2小层与五峰组页岩储层裂缝多为裂缝长度/岩芯周长小于25%的短裂缝,平均占比79.8%。(2)龙一1亚段1小层岩芯裂缝发育,其中以平行于层理的裂缝为主,龙一1亚段2小层天然微裂缝数量略低于1小层,而五峰组岩芯仅发现极少量微观可见的天然微裂缝。(3)岩芯表面观测到的主要矿物为黄铁矿、方解石。本文的主要创新点在于通过直观的方法对川南龙马溪组储层页岩的裂缝特征进行了统计分析,对于后续页岩气开采以及储层气体流动分析具有十分重要的意义。

       

      Abstract: There are huge reserves of shale gas resources in China, and the Sichuan Basin is the main production area. An important indicator in shale gas exploration and development is fracture characteristics and carries the two major functions of gas storage and transportation channels. Therefore, understanding the microscopic characteristics of reservoir fractures is of great significance for evaluating the gas content of the reservoir and the development prospects. In this paper, the main research object is the core of shale gas Well Lu 201. The well is located in the main shale gas production area in Southern Sichuan. With handheld microscope and stereo microscope as the main observation tools, observation experiments on the core were carried out. This paper also uses image software to reconstruct images of the core surface, statistically analyses the types, reservoir fracture characteristics, development characteristics and mineral characteristics, and successfully constructs two-dimensional shale fracture models. Through microscope observation this paper finds that: (1)Fractures in the 1st and 2nd sub-layers of the Longyi 1 sub-member of the Longmaxi Formation and Wufeng Formation shale reservoirs are mostly short fractures, accounting for 79.8% of the total fractures, with fracture length/core circumference less than 25%. (2)Fractures are well developed in the core of the Longyi 1 sub-member 1st small layer, and the fractures are mainly parallel to the bedding planes. The natural fracture number in the 2nd small layer of the Longyi 1 sub-member is slightly lower than that of the 1st small layer, while in the Wufeng formation only a very small number of natural fractures are observed. (3)The main minerals observed on the surface of the core are pyrite and calcite. The main innovation of this paper is the statistical analysis of the fracture characteristics of the Longmaxi Formation shale reservoir in Southern Sichuan through an intuitive method. and this research is of great significance for shale gas production and reservoir gas flow analysis.

       

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