石油学报 ›› 2020, Vol. 41 ›› Issue (6): 723-736.DOI: 10.7623/syxb202006007

• 地质勘探 • 上一篇    下一篇

富镜质组和富惰质组高阶煤纳米孔隙结构特征

单长安1,2,3, 张廷山4, 梁兴5, 胡冉冉5, 赵卫卫1   

  1. 1. 西安石油大学地球科学与工程学院 陕西西安 710065;
    2. 油气藏地质及开发工程国家重点实验室(成都理工大学) 四川成都 610059;
    3. 陕西省油气成藏地质学重点实验室 陕西西安 710065;
    4. 西南石油大学地球科学与技术学院 四川成都 610500;
    5. 中国石油浙江油田公司 浙江杭州 310023
  • 收稿日期:2019-03-30 修回日期:2020-02-17 出版日期:2020-06-25 发布日期:2020-07-11
  • 通讯作者: 单长安,男,1985年11月生,2009年获西南石油大学学士学位,2016年获西南石油大学博士学位,现为西安石油大学讲师,主要从事非常规油气储层微观机理相关研究工作。
  • 作者简介:单长安,男,1985年11月生,2009年获西南石油大学学士学位,2016年获西南石油大学博士学位,现为西安石油大学讲师,主要从事非常规油气储层微观机理相关研究工作。Email:shanca@xsyu.edu.cn
  • 基金资助:

    油气藏地质及开发工程国家重点实验室（成都理工大学）开放基金项目（PLC20190503）、陕西省自然科学基础研究计划项目（2019JQ-100）、陕西省教育厅科研计划项目（18JK0620）、国家科技重大专项（2017ZX05039-001-002）和国家自然科学基金项目（No.41702127）资助。

Nanopore structure characteristics of high-rank vitrinite- and inertinite-coal

Shan Chang'an1,2,3, Zhang Tingshan4, Liang Xing5, Hu Ranran5, Zhao Weiwei1   

  1. 1. School of Earth Sciences and Engineering, Xi'an Shiyou University, Shaanxi Xi'an 710065, China;
    2. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(Chengdu University of Technology), Sichuan Chengdu 610059, China;
    3. Shaanxi Key Laboratory of Petroleum Accumulation Geology, Xi'an Shiyou University, Shaanxi Xi'an 710065, China;
    4. School of Geoscience and Technology, Southwest Petroleum University, Sichuan Chengdu 610500, China;
    5. PetroChina Zhejiang Oilfield Company, Zhejiang Hangzhou 310023, China
  • Received:2019-03-30 Revised:2020-02-17 Online:2020-06-25 Published:2020-07-11

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摘要：

针对四川盆地南部筠连地区煤层气井挑选了16个镜质组含量大于75%和7个惰质组含量大于75%的高阶煤样，进行了扫描电镜、低温氮气吸附实验和核磁共振物性测试分析，对富镜质组和富惰质组高阶煤的纳米级孔隙结构特征进行了系统的定性和定量对比研究。研究结果表明：惰质组相对于镜质组原生孔（植物组织孔）更为发育，而后生孔（气孔）和外生孔（角砾孔和破裂孔）在镜质组中更为发育；富镜质组和富惰质组高阶煤均具有复杂的纳米级孔隙结构，然而富惰质组高阶煤孔隙形态更为复杂特殊（墨水瓶状孔更为发育）；富镜质组和富惰质组高阶煤的吸附曲线形态在初始阶段（p/p0<0.05）存在明显的差异，富惰质组煤样的吸附曲线在初始阶段（p/p0<0.05）均出现快速上升的现象，而富镜质组煤样在该阶段均呈现出缓缓上升的特点，由此得出惰质组中含有更多孔径小于0.64 nm的分子级孔；富惰质组高阶煤中平均孔比表面积、平均孔体积及氮气吸附量均大于富镜质组高阶煤，二者纳米孔隙平均孔径相近；富镜质组和富惰质组高阶煤中对孔比表面积起到主要贡献的孔径均分布在2~4 nm，可推测两种煤中小于4 nm的孔隙在各级孔中所占比例最大；富镜质组高阶煤中平均孔径对孔容具有明显贡献的主要为大于10 nm的孔，而惰质组中平均孔径从2 nm开始便具有了明显贡献，由此得出2~10 nm的纳米孔在惰质组中更为发育；镜质组和惰质组中的孔隙度、渗透率和束缚水饱和度的值接近，且孔隙度与渗透率之间具有非常明显的指数正相关关系；富镜质组高阶煤中束缚水饱和度与孔隙度之间没有明显的相关关系，而束缚水饱和度与渗透率之间具有较好的负相关性；富惰质组高阶煤中束缚水饱和度与孔隙度和渗透率均具有较为明显的负相关性。

关键词: 富镜质组, 富惰质组, 高阶煤, 纳米孔隙结构, 差异性

Abstract:

Sixteen high-rank coal samples with the vitrinite content greater than 75% and seven high-rank coal samples with the inertinite content greater than 75% were selected from coalbed methane wells in the Junlian area in the southern Sichuan Basin. Using scanning electron microscopy, in combination with low temperature nitrogen adsorption experiment and physical property test analysis based on nuclear magnetic resonance, this paper systematically, qualitatively and quantitatively compare and study the nanopore structure characteristics of high-rank vitrinite- and inertinite-rich coal. The results show that primary pores (vegetable tissue pores) are more developed in the inertinite than in the vitrinite, while epigenetic pores (stomata) and exogenous pores (breccia pores and fracture pores) are more developed in the vitrinite. Both the high-rank vitrinite- and inertinite-rich coal has a complex nano-scale pore structure, but the pore morpholohy of high-rank inertinite-rich coal is more complex and special (the ink bottle-shaped pores are more developed). There are significant differences in the forms of the adsorption curves of high-rank vitrinite- and inertinite-rich coal at the initial stage (p/p0<0.05). The adsorption curve of the inertinite-rich coal samples showed a rapid increase at the initial stage (p/p0<0.05), and that of the vitrinite-rich coal samples rose slowly at this stage. Thus, the inertinite contains more molecular pores with a pore size of less than 0.64 nm. The average pore specific surface area, average pore volume and nitrogen adsorption of high-rank inertinite-rich coal are larger than those of the high-rank vitrinite-rich coal, and their average pore diameter of nanopores is nearly the same. The pore diameters of 2-4 nm play a major role in the pore specific surface area of high-rank vitrinite- and inertinite-rich coal. It can be speculated that pores with the pore diameter less than 4 nm account for the largest proportion of pores at all levels in those two kinds of coal. Pores with the average pore diameter larger than 10 nm in high-rank vitrinite-rich coal have a significant contribution to pore volume, while those with the average pore diameter greater than 2 nm have an obvious contribution. It is concluded that the nanopores with a pore diameter between 2 nm and 10 nm are more developed in the inertinite. The porosity, permeability and irreducible water saturation in the vitrinite and inertinite are nealy the same, and the porosity is exponentially positively correlated with the permeability. There is no obvious correlation between the irreducible water saturation and the porosity in high-rank vitrinite-rich coal, but there is a good negative correlation between the irreducible water saturation and the permeability. There is an obvious negative correlation between the irreducible water saturation, porosity and permeability in high-rank inertinite-rich coal.

Key words: vitrinite-rich, inertinite-rich, high-rank coals, nano-scale pore structure, difference

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