Acta Petrolei Sinica ›› 2019, Vol. 40 ›› Issue (12): 1485-1494.DOI: 10.7623/syxb201912007

• Petroleum Exploration • Previous Articles     Next Articles

Influence of different polar solvent extraction on pore structure in shale

Lin Xiaoying1,2, Huang Meixin2, Chen Hao2, Wang Jian2, Wang Ruijie3   

  1. 1. School of Water Conservancy Engineering, Zhengzhou University, Henan Zhengzhou 450001, China;
    2. School of Energy Science and Engineering, Henan Polytechnic University, Henan Jiaozuo 454000, China;
    3. College of Petroleum Engineering, China University of Petroleum, Beijing 102249, China
  • Received:2018-05-15 Revised:2019-03-08 Online:2019-12-25 Published:2020-01-04

不同极性溶剂萃取对泥页岩孔隙结构的影响

林晓英1,2, 黄美鑫2, 陈浩2, 王健2, 王瑞杰3   

  1. 1. 郑州大学水利科学与工程学院 河南郑州 450001;
    2. 河南理工大学能源科学与工程学院 河南焦作 454000;
    3. 中国石油大学(北京)石油工程学院 北京 102249
  • 通讯作者: 林晓英,女,1980年3月生,2002年获河南理工大学学士学位,2012年获中国石油大学(北京)博士学位,现为郑州大学水利科学与工程学院副教授,主要从事煤层气、页岩气、煤系气地质方面研究。Email:lxy2002199@126.com
  • 作者简介:林晓英,女,1980年3月生,2002年获河南理工大学学士学位,2012年获中国石油大学(北京)博士学位,现为郑州大学水利科学与工程学院副教授,主要从事煤层气、页岩气、煤系气地质方面研究。Email:lxy2002199@126.com
  • 基金资助:

    国家自然科学基金项目(No.41402142)、中国博士后基金项目(2015M572106)和河南省教育厅重点项目(14B44001)资助。

Abstract:

Shale's pore type and structure will directly affect the occurrence and production of gas. To discuss the effect of soluble organic matters in shale on the pore structure, different polar soluble organic matters in the shale are separated and extracted in the order of n-hexane, dichloromethane and tetrahydrofuran. Further, using the field emission scanning electron microscope (FE-SEM)and low-temperature nitrogen adsorption tests, this paper comparatively analyzes the pore structure characteristics of original sample and raffinate, and explores the effects of different polar solvent extraction on the pore structure of shale. The results show that with the increasing of organic solvent polarity, the soluble organic matters in shale are dissolved in the order of saturated hydrocarbons, aromatic hydrocarbons and non-hydrocarbon components. The original pores mainly include four types:intergranular pores, intragranular pores, organic pores and micro-cracks. After the soluble organic matters are dissolved, the pore morphology is more irregular, thus forming more dissolved pores; some intergranular pores are filled with the detached debris. Solvent polarity is enhanced, the area of hysteresis loop is reduced, and the BJH pore volume and average pore size are increased, accompanied by insignificant change in the BET specific surface area. The dissolution of soluble organic matter has the effect of "enhancing pores" and "expanding pores" on shale, with the increased pore content ≤ 2 nm and relatively decreased pore content>2 nm. In the mesopore range, the percentage content of pore volume and specific surface area is decreased in the pores of 2-10 nm, with insignificant change in the pore size range of 10-30 nm and significant increase in the pore size range of 30-50 nm. The modification process of pore morphology is as follows:the "ink bottle" hole with a relatively large aperture ratio of bottle body to bottle neck→the "ink bottle" hole with a relatively small aperture ratio of bottle body to bottle neck→wedge-type hole→parallel plate hole.

Key words: shale, soluble organic matters, pore structure, enhancing pores, expanding pores

摘要:

页岩的孔隙类型与孔隙结构直接影响着气体的赋存和产出。为了研究泥页岩中可溶有机质对孔隙结构的影响,按照正己烷、二氯甲烷、四氢呋喃的顺序依次对泥页岩中不同极性可溶有机质进行分离与抽提,利用场发射扫描电子显微镜(FE-SEM)和低温氮气吸附实验,对比分析了原始样品和萃余物的孔隙结构特征,探讨了不同极性溶剂萃取对泥页岩孔隙结构的影响。结果表明:随着有机溶剂极性的增强,泥页岩中的可溶有机质依次按照饱和烃、芳香烃和非烃组分顺序溶出;原始样品的孔隙主要为粒间孔、粒内孔、有机质孔和微裂缝4种类型,可溶有机质溶出后,孔隙形态更为不规则,出现更多溶蚀孔,部分粒间孔被脱落黏土矿物碎屑充填;溶剂极性增强,滞后圈的面积减小,BJH孔体积和平均孔径增加,BET比表面积变化不明显;可溶有机质的溶出对泥页岩具有"增孔"和"扩孔"作用,孔径≤2 nm的孔隙含量增加,孔径>2 nm的孔隙含量减少;2~10 nm孔径范围内孔体积和孔比表面积的百分含量减小,10~30 nm孔径范围内变化不明显,30~50 nm孔径范围内明显增加;对孔隙形态的改造过程为:瓶身与瓶颈的孔径比相对较大的"墨水瓶"孔→瓶身与瓶颈的孔径比相对较小的"墨水瓶"孔→楔形孔→平行板状孔。

关键词: 泥页岩, 可溶有机质, 孔隙结构, 扩孔, 增孔

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