刘宇, 彭平安. 不同矿物组分对泥页岩纳米孔隙发育影响因素研究[J]. 煤炭学报, 2017, (3). DOI: 10.13225/j.cnki.jccs.2016.0580
引用本文: 刘宇, 彭平安. 不同矿物组分对泥页岩纳米孔隙发育影响因素研究[J]. 煤炭学报, 2017, (3). DOI: 10.13225/j.cnki.jccs.2016.0580
LIU Yu, PENG Ping-an. Research on the influences of different mineral compositions on the development of nanopores in shales[J]. Journal of China Coal Society, 2017, (3). DOI: 10.13225/j.cnki.jccs.2016.0580
Citation: LIU Yu, PENG Ping-an. Research on the influences of different mineral compositions on the development of nanopores in shales[J]. Journal of China Coal Society, 2017, (3). DOI: 10.13225/j.cnki.jccs.2016.0580

不同矿物组分对泥页岩纳米孔隙发育影响因素研究

Research on the influences of different mineral compositions on the development of nanopores in shales

  • 摘要: 选择四川盆地长宁双河镇上奥陶统五峰组—下志留统龙马溪组新鲜露头剖面样品,通过化学方法去除其中碳酸盐、硅酸盐及黄铁矿,利用低温二氧化碳和氮气吸附法对各处理阶段样品的纳米孔隙结构进行测定,通过等温线和NLDFT分析,对孔隙结构进行表征并分析不同矿物组分对原岩样品孔隙结构的影响。结果表明,对微孔部分而言,去除碳酸盐造成微孔体积减小,而去除硅酸盐和黄铁矿过程导致微孔体积增加,说明碳酸盐提供了页岩内部分微孔体积,可能来自于溶蚀孔的影响;对介孔-大孔部分而言,孔体积随着去矿物过程深入持续增加,说明矿物组分对这部分孔隙贡献较小。去矿物过程对样品不同尺度孔隙比例分布未产生明显影响,显示了介孔占据主要孔体积部分,微孔提供主要的表面积的特征。就孔径分布而言,微孔部分孔径分布受去矿物过程影响较大,而介孔-大孔部分孔径分布受去矿物过程影响较小。全岩样品微孔隙总体上体现了有机质孔隙发育特征,不同矿物组分在一定程度上由于和有机质处于包裹、填充、被填充的状态,对有机质原始孔隙信息,尤其是微孔部分起到更加明显的掩盖作用。总的来说,有机质是控制泥页岩微孔隙发育的最重要因素。

     

    Abstract: In order to characterize the pore structure and analyze the influences of different mineral components on the pore structure of shale,some chemical methods were used to remove carbonate,silicate and pyrite in the samples col- lected from fresh outcrop sections of Wufeng-Longmaxi Formation located at Shuanghe Town,Changning County in Si- chuan Basin. The nanopores structure of samples at the different stages of processing were measured by carbon dioxide and nitrogen adsorption and analyzed by isotherms and NLDFT method. The results show that for micropores,the re- moval of carbonate reduces the volume of micropores,while the removal of silicate and pyrite results in an increase of the volume of micropores. This phenomenon indicates the dissolved pores in carbonate provide some micropores for the shale. For the meso-macropores,the pore volume shows an increasing trend during the processes of removing the minerals,indicating the minor contribution of minerals for these types of pores. The proportional distributions of pores in different scales have no changes during the processes of removing minerals,showing a characteristic that the mesopores and micropores provide the pore volume and surface area,respectively. The pore size distribution of micropore has a more obvious influence by the mineral constituent than that of meso-macropore. The nanopores in the whole rock show the characteristic of pores in organic matter,the minerals in shale cover the original information of organic matter,es- pecially for the micropore,this is due to the minerals are in packed,fill or filled conditions with the organic matter. In summary,the organic matter is the most important factor in controlling the evolution of nanopores in shales.

     

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