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现代地质 ›› 2020, Vol. 34 ›› Issue (02): 273-280.DOI: 10.19657/j.geoscience.1000-8527.2019.016

• 煤田地质学 • 上一篇    下一篇

煤岩演化程度对煤储层孔裂隙结构的控制作用

樊祺章1,2(), 蔡益栋1,2(), 贝金翰1,2, 王玮昊1,2, 张学英3   

  1. 1.中国地质大学(北京) 能源学院,北京 100083
    2.煤层气开发利用国家工程中心煤储层实验室,北京 100083
    3.中国石油 华北油田分公司,河北 任丘 062552
  • 收稿日期:2018-04-03 修回日期:2019-10-20 出版日期:2020-05-25 发布日期:2020-05-25
  • 通讯作者: 蔡益栋
  • 作者简介:蔡益栋,男,副教授,博士研究生导师,1985年出生,矿产普查与勘探专业,主要从事煤层气地质与开发研究。Email: yidong.cai@163.com
    樊祺章,男,硕士研究生,1997年出生,地质工程专业,主要从事煤层气地质与开发研究。Email: qizhangfan@163.com
  • 基金资助:
    国家自然科学基金项目(41602170)

Pore and Fracture Structure of Coal Reservoir Constrained by Coal Metamorphism

FAN Qizhang1,2(), CAI Yidong1,2(), BEI Jinhan1,2, WANG Weihao1,2, ZHANG Xueying3   

  1. 1. School of Energy Resources, China University of Geosciences, Beijing 100083, China
    2. Coal Reservoir Laboratory of National Engineering Research Center of Coalbed Methane Development & Utilization, Beijing 100083, China
    3. Huabei Oilfield Company, PetroChina, Renqiu,Hebei 062552, China
  • Received:2018-04-03 Revised:2019-10-20 Online:2020-05-25 Published:2020-05-25
  • Contact: CAI Yidong

摘要:

为研究煤岩演化程度对孔裂隙结构发育的影响,运用压汞、低温氮吸附/解吸、镜质组反射率测试和SEM、荧光显微观察等手段,分析煤岩变质程度对孔隙度、BET比表面积、BJH总孔体积、裂隙结构和密度等的影响。结果表明:随变质程度升高,煤岩孔隙度呈先增大后减小再略微增大的波动变化特征;微孔占比随煤岩镜质组反射率升高呈“U”形变化特征,小孔占比变化与之相反;煤岩BET比表面积和BJH总孔体积均随煤级升高呈“U”形变化特征;中高变质程度煤岩中B、C、D型裂隙密度随煤级的升高都呈“U”形变化,并在Ro,m=1.1%左右出现最小值,裂隙密度下降阶段中D型裂隙密度降低最快。结合镜质组反射率分析发现,煤岩孔(裂)隙的发育与煤岩演化的4次跃变有着密切关系。

关键词: 煤, 变质程度, 孔隙, 微裂隙

Abstract:

To study the effects of coal metamorphism on the structure of pores and fractures, mercury intrusion porosimetry, low temperature nitrogen adsorption/desorption, vitrinite reflectance test, scanning electron microscopic (SEM) analysis, and fluorescence microscopy observation, were conducted to investigate the influence of coal metamorphic degree on porosity, Brunauer-Emmett-Teller (BET) specific surface area, Barrett-Joyner-Halenda (BJH) total pore volume and fracture structure and density. The results indicate that with increasing coal metamorphism, the coal porosity increases first and then decreases, and finally increases slightly. Micropore volume (<10 nm) shows a U-shaped change with the increase of vitrinite reflectance, and small pores show an inverted U-shaped trend. The BET specific surface area, BJH total pore volume, and fracture density (fracture type B, C, and D) of medium- to high-grade metamorphosed coal have the same U-shaped trend. However, for type B, C, and D facture density of medium- to high-grade metamorphosed coal, the minimum values occur near Ro,m=1.1%, and the fracture density reduction of type D fractures is highest when the fracture density decreases. Integrated with the results of vitrinite reflectance, the pore and fracture development are closely related to the four abrupt changes of the coal metamorphism.

Key words: coal, metamorphic degree, pore, microscopic fracture

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