金佳旭, 付彦吉, 郑旭, 等. 2022. 氧化对牛蹄塘组页岩孔隙结构影响的试验研究[J]. 工程地质学报, 30(1): 205-215. doi: 10.13544/j.cnki.jeg.2021-0101.
    引用本文: 金佳旭, 付彦吉, 郑旭, 等. 2022. 氧化对牛蹄塘组页岩孔隙结构影响的试验研究[J]. 工程地质学报, 30(1): 205-215. doi: 10.13544/j.cnki.jeg.2021-0101.
    Jin Jiaxu, Fu Yanji, Zheng Xu, et al. 2022. Experimental study on effect of oxidation on pore structure of Niutitang shale[J]. Journal of Engineering Geology, 30(1): 205-215. doi: 10.13544/j.cnki.jeg.2021-0101.
    Citation: Jin Jiaxu, Fu Yanji, Zheng Xu, et al. 2022. Experimental study on effect of oxidation on pore structure of Niutitang shale[J]. Journal of Engineering Geology, 30(1): 205-215. doi: 10.13544/j.cnki.jeg.2021-0101.

    氧化对牛蹄塘组页岩孔隙结构影响的试验研究

    EXPERIMENTAL STUDY ON EFFECT OF OXIDATION ON PORE STRUC ̄TURE OF NIUTITANG SHALE

    • 摘要: 页岩气作为一种高效、清洁能源对我国的能源结构改革具有重要意义。由于页岩具有埋深大、地应力较高、孔隙率低等特点导致页岩气开采效率极低。为了探究氧化作用对牛蹄塘页岩的反应机理及在氧化作用下孔隙结构的变化,及探究合理的试验方案进而提高页岩的渗透率和页岩气的开采效率。本文以湖南牛蹄塘组页岩为研究对象,采用30%的过氧化氢溶液对牛蹄塘组页岩试样进行分级浸泡后采用超景深显微镜观察试样表面孔隙结构变化和裂隙演化规律;采用扫描电镜观测氧化前后页岩自然断面和由于氧化作用导致断裂层理面微观结构的变化;采用压汞实验测定氧化前后试样的孔隙结构和氧化作用对页岩孔隙率的改变。结果表明:1牛蹄塘组页岩在浸泡8 h后开始逐渐反应产生大量气泡并在试样表面产生附着物,试样层理间力学性质随反应进行不断弱化,最终试样沿层理断裂。2通过扫描电镜观察到在原始页岩试样中铁元素以硫铁矿形式大面积附着在黏土表面,氧化后硫铁矿中的硫元素基本被氧元素替换。3通过压汞实验得到氧化360 h后的试样较原始试样的孔隙体积由0.041 mL·g-1提升到0.137 mL·g-1、孔隙率由9.35%提升至25.35%。由此可得,氧化对富有机质页岩的孔隙结构产生显著变化、增强了页岩气在页岩中的运移能力。

       

      Abstract: Shale gas,as efficient and clean energy,plays a significant role in the energy mix nowadays. The 30% of hydrogen peroxide is used to immerse the shale sample(Niutitang Formation,Hunan Province) in order to increase the porosity and gas transportability. The variation of microscopic pore structure is observed by the super depth of field microscope and mercury injection experiment. Also,the variations of the microstructure of natural and oxidized fractures before and post immersion determined are determined by scanning electron microscopy. The three results are found. (1)Lots of bubbles and adhesions appear on the surface of the samples leading to the reduction of mechanical strength and breakage of the sample. (2)The observation of scanning electron microscope shows that iron element is attached to the surface of clay in the form of pyrite. The sulfur in pyrite is replaced by oxygen after oxidation. (3)After immersion the pore volume is increased from 0.041 mL·g-1 to 0.137 mL·g-1 with porosity from 9.35% to 25.35%. Based on the above results,it can be concluded that oxidation can significantly change the pore structure of organic-rich shale enhancing the migration ability of gas.

       

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