循环微波辐射下含水煤体的孔隙结构演化机制

doi:10.16265/j.cnki.issn1003-3033.2024.11.0347

摘要/Abstract

摘要：

为更好利用微波增透技术安全高效地抽采煤层瓦斯,探究循环微波条件下煤体含水量变化对增透效果的影响,首先,通过核磁共振(NMR)技术获得表征煤样孔隙结构特征的横向弛豫时间(T₂)谱和纵向弛豫时间(T₁)-T₂谱;然后,利用T₂数据得到核磁特征参数,进一步明确循环微波辐射下煤体孔隙结构演化随含水量变化的情况;最后,基于循环微波增透机制,揭示不同含水煤体的孔隙结构演化机制。结果表明:循环微波辐射下,不同含水饱和度煤体的孔隙结构均得到明显改善,其中75%含水饱和度煤样具有比其他试验煤样更佳的增透效果。循环微波辐射促使孔隙向更大孔径演化过程中,煤体由于发生热破裂而出现孔隙堵塞现象,提高含水饱和度可以减少此现象出现;循环微波增透主要依靠热应力和气压驱动,随着煤体透气性的改善,微波增透效果有所减弱,煤体含水量的影响随之减弱。

关键词: 煤层瓦斯, 循环微波辐射, 含水煤体, 孔隙结构, 核磁共振(NMR)

Abstract:

In order to better use microwave antireflection technology to safely and efficiently extract coal seam gas, and to explore the influence of coal moisture content change on the antireflection effect under cyclic microwave conditions, firstly, the transverse relaxation time (T₂) spectrum and longitudinal relaxation time (T₁) -T₂ spectrum characterizing the pore structure characteristics of coal samples were obtained by NMR technology. Then, the characteristic parameters of nuclear magnetic resonance were obtained by using T₂ data, and the change of pore structure evolution with water content under cyclic microwave radiation was further clarified. Finally, based on the mechanism of cyclic microwave permeability enhancement, the pore structure evolution mechanism of different water-bearing coal bodies was revealed. The results show that the pore structure of coal with different water saturation is obviously improved under cyclic microwave radiation, and the coal sample with 75% water saturation has a better antireflection effect than other test coal samples. In the process of cyclic microwave radiation promoting the evolution of pores to larger pores, pore blockage occurs due to the thermal fracture of coal, and increasing water saturation can reduce this phenomenon. The cyclic microwave anti-reflection mainly relies on thermal stress and air pressure. With the improvement of coal permeability, the effect of microwave anti-reflection is weakened, and the influence of coal water content is weakened.

Key words: coal seam gas, cyclic microwave radiation, water-contained coal, pore structure, nuclear magnetic resonance(NMR)

中图分类号:

X936

李贺, 蒋训祁, 鲁义, 施式亮, 路洁心, 曹洁艳. 循环微波辐射下含水煤体的孔隙结构演化机制[J]. 中国安全科学学报, 2024, 34(11): 99-107.

LI He, JIANG Xunqi, LU Yi, SHI Shiliang, LU Jiexin, CAO Jieyan. Evolution mechanism of pore structure of water-bearing coal under cyclic microwave radiation[J]. China Safety Science Journal, 2024, 34(11): 99-107.

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孔隙类型	含水饱和度/%	T₂谱面积				总增幅程度/%
孔隙类型	含水饱和度/%	原煤	循环1次后	循环2次后	循环3次后	总增幅程度/%
吸附孔	0	2 025.836	1 937.267	1 884.41	1 871.838	-7.60
	25	1 865.448	1 887.79	1 880.006	1 880.845	0.83
	50	2 023.991	1 959.765	1 934.842	1 915.345	-5.37
	75	2 005.109	1 767.157	1 917.584	1 908.728	-4.81
	100	1 941.281	1 902.382	1 873.722	1 854.638	-4.46
渗流孔	0	956.843	1 199.496	1 241.696	1 332.215	39.23
	25	1 341.829	1 396.15	1 456.57	1 501.088	11.87
	50	1 071.94	1 193.319	1 202.64	1 363.123	27.16
	75	983.021	1 287.142	1 432.735	1 454.605	47.97
	100	1 010.553	1 235.637	1 306.645	1 359.339	34.51
总孔隙	0	2 982.679	3 136.763	3 126.106	3 204.053	7.42
	25	3 207.277	3 283.94	3 336.576	3 381.933	5.45
	50	3 095.931	3 153.084	3 137.482	3 278.468	5.90
	75	2 988.13	3 054.299	3 350.319	3 363.333	12.56
	100	2 951.834	3 138.019	3 180.367	3 213.977	8.88