煤体中瓦斯水合固化的力学作用研究进展_中国煤炭行业知识服务平台

煤体中瓦斯水合固化的力学作用研究进展

Title

Progress in the mechanical effects of gas solidification by hydrate in coal
作者

吴强张保勇
Author

WU Qiang;ZHANG Baoyong
单位

黑龙江科技大学安全工程学院
Organization

School of Safety Engineering, Heilongjiang University of Science & Technology
摘要

为更好地完善我国煤与瓦斯突出预测与防治方法，基于煤与瓦斯突出综合作用假说，提出了瓦斯水合固化防治煤与瓦斯突出的方法。该方法核心是将煤层中瓦斯固化生成瓦斯水合物，不仅能降低瓦斯压力，而且能够提高煤体强度，以达到减弱或消除煤与瓦斯突出危险性的目的。实现了煤体中瓦斯水合物的生成以及含瓦斯水合物煤体力学性质−渗透率原位测试，提出了煤体中瓦斯水合物生成及力学性质−渗透率测试技术及含瓦斯水合物煤体三轴压缩数值建模技术。瓦斯水合固化热力学和动力学条件是防突的理论基础，煤层瓦斯水合物稳定储存是技术前提，瓦斯压力降低及煤体力学性质改善是防突关键，重点围绕水合固化煤体交叉力学问题进行总结。分析认为：① 瓦斯水合固化防突技术理论框架已经初步形成，并利用数值模拟手段初步探究了瓦斯水合固化对煤体力学特征改善的细观机理；② 现阶段已证实煤体中水合物生成不仅能降低瓦斯压力，而且能改善其力学性质，高饱和度对提高煤体峰值强度明显；③ 瓦斯水合物生成经历快速、缓慢和稳定3个阶段，且水合物的生成会造成煤体中瓦斯渗流通道阻塞，导致其渗透率降低；④ 高瓦斯压力、高CH₄体积分数不仅有助于提高水合物饱和度而且会延缓水合物分解，有助于水合物的稳定存在。需要注意的是，瓦斯水合固化技术防突的可靠度仍需大量重复试验验证，以建立普适化的数据库。综合现有研究结果，对水合固化防突研究目前仍存在的局限性与挑战进行了讨论，并且给出了进一步的研究方向。
Abstract

Aiming at the real problems such as the occurrence of coal and gas outburst and based on the hypothesis of comprehensive action of coal and gas outburst, a method of gas hydration and solidification to prevent coal and gas outburst is proposed. The core of this method is to solidify the gas in coal seam to form gas hydrate, which can not only reduce the gas pressure, but also improve the coal strength, so as to reduce or eliminate the risk of coal and gas outburst. Based on the idea of “coal and gas outburst prevention using hydrate”, the test of gas hydrate formation in coal and the in-situ test of the mechanical property-permeability of gas hydrate bearing coal have been performed, with the numerical modeling technique of the triaxial compression of the gas hydrate bearing coal proposed. The techniques are implemented by comprehensively applying the methods of theoretical analysis, development of testing equipment, indoor test and numerical analysis. In terms of coal and gas outburst prevention, the thermodynamic and kinetic conditions of gas hydrate formation are its theoretical basis, the stable storage of gas hydrate is its technical precondition, and the reduction of gas pressure and the improvement of mechanical properties are its key measures. This paper focuses on the cross mechanics related to the gas hydrate bearing coal. The results show that: ① the theoretical framework of gas solidification technology by the hydrate method for outburst prevention has been initially formed, and the meso-mechanism of improving the mechanical characteristics of coal before and after gas hydration has been preliminarily explored by means of the numerical simulation. ② At present, it has been confirmed that the hydrate formation in coal can not only reduce the gas pressure, but also improve its mechanical properties. High saturation can obviously improve the peak strength of coal. ③ Gas hydrate formation experiences three stages: rapid, slow and stable stage. Additionally, the formation of hydrate will cause the gas seepage channel in the coal to be blocked, resulting in a decrease in its permeability. ④ High gas pressure and high CH4 concentration not only help to increase the saturation but also delay hydrate decomposition, which is conducive to the stable existence of the hydrate. However, a large number of repetitive experiments are still needed to verify the reliability of the method to build up a generalized database. By analyzing current research findings, the limitations and challenges that still exist are discussed, with further research interests pointed out.
关键词

煤与瓦斯突出瓦斯水合固化含瓦斯水合物煤体力学性质离散元
KeyWords

coal and gas outburst;gas solidification by the hydrate method;gas hydrate bearing coal;mechanical behavior;discrete element method
基金项目(Foundation)

国家自然科学基金资助项目(U21A20111, 51974112, 51674108)
DOI

10.13225/j.cnki.jccs.ST23.1482
引用格式

吴强，张保勇. 煤体中瓦斯水合固化的力学作用研究进展[J]. 煤炭学报，2024，49(2)：720−738.
Citation

WU Qiang，ZHANG Baoyong. Progress in the mechanical effects of gas solidification by hydrate in coal[J]. Journal of China Coal Society，2024，49(2)：720−738.
相关文章

[1]十二烷基硫酸钠对瓦斯水合物生长速率的影响
[2]瓦斯水合物生成控制因素探讨
[3]晶体类型对含瓦斯水合物煤体力学性质的影响
[4]含瓦斯水合物煤体强度特性三轴试验研究
[5]卸围压条件下含瓦斯水合物煤体应力-应变特性试验研究
[6]饱和度对含瓦斯水合物煤体渗透率影响试验研究
[7]柔性边界三轴压缩条件下含瓦斯水合物煤体宏细观力学性质
[8]加卸载条件下含瓦斯水合物煤体应变及渗透率试验研究

图表

不同饱和度下含瓦斯水合物煤体接触个数、接触力、配位数以及孔隙率与轴向应变的关系[46]

Table1

温度/℃	0	5.0	10.0	20.0
压力/MPa	2.55	4.24	6.95	21.28

Table2

时间	作者	部分结论
1981	MAKOGON YF^[14]	国内外最早提出煤层中可能存在水合物
2021	VIKTOR V. Nikitin等^[15]	由于适合的温压条件及水和甲烷的丰富性，煤层中可能存在水合物
1992	俞启香^[16]	煤层瓦斯气体可能以瓦斯水合物晶体存在
2006	吴强等^[17]	在中高纬度矿区的煤层中有瓦斯水合物自然存在的可能
2006	于洪观等^[18]	煤层中存在着甲烷水合物形成的物质、储存和温压条件，可能存在水合物
2008	李祥春等^[19]	吨煤瓦斯突出量高出吨煤瓦斯含量很多，为煤层中甲烷水合物的存在提供佐证

Table3

编号	煤体瓦斯体积/m³	孔隙率\( \varphi \)/ %	不可解吸量/ m³	固化前破碎后压力P₁/MPa	饱和度 S_h/%	固化瓦斯体积/m³	固化后破碎后压力P₂/MPa	瓦斯压力降低率/%
1	8	10	0.8	0.79	20	3.28	0.43	45.57
20	6.56	0.07	91.14
2	10	10	1.0	0.98	20	3.28	0.62	36.73
20	6.56	0.27	72.45
3	15	10	1.5	1.47	40	6.56	0.76	48.30
20	13.12	0.04	97.28
4	20	10	2.0	1.97	40	6.56	0.76	61.42
20	13.12	0.53	73.10
5	25	10	2.5	2.46	60	9.84	1.38	43.90
20	19.68	0.31	87.40
6	30	10	3.0	2.95	60	9.84	1.87	36.61
20	19.68	0.80	72.88
7	40	10	4.0	3.93	80	13.12	2.60	33.84
20	26.24	1.07	72.77
8	45	10	4.5	4.42	80	13.12	2.99	32.35
20	26.24	1.56	64.71

Table4

瓦斯气样	瓦斯气样组分
G1	φ(CH₄)=99.99%
G2	φ(CH₄)=85%、φ(CO₂)=8%、φ(N₂)=5.6%、φ(O₂)=1.4%
G3	φ(CH₄)=80%、φ(CO₂)=8%、φ(N₂)=9.6%、φ(O₂)=2.4%
G4	φ(CH₄)=75%、φ(CO₂)=8%、φ(N₂)=13.6%、φ(O₂)=3.4%

Table5

编号	指标	计算方法	参数
1	渗透率^[47]	\( {k}{=}\dfrac{{2}{\mu}{{P}}_{{0}}{LQ}}{{A}{{(}{P}}_{{1}}^{{2}}{–}{{P}}_{{2}}^{{2}}{)}} \)	μ为测量温度下气体黏度系数；P₀为大气压力；P₁为进气压力；P₂为出气压力；L为试样长度；A为试样横截面面积；Q为瓦斯流量
2	渗透率变化率^[48]	\( {{B}}_{{{\mathrm{P}}}}{=}\dfrac{{{k}}_{{1}}{–}{{k}}_{{{\mathrm{m}}}}}{{{k}}_{{1}}} \)	k₁为第1个瓦斯压力下的渗透率；k_m为瓦斯压力变化过程的渗透率
3	瓦斯压力敏感系数^[48]	\( {{C}}_{{{\mathrm{P}}}}=-\dfrac{{1}}{{{k}}_{{1}}}\dfrac{{\partial k}}{{{\partial P}}_{{{\mathrm{m}}}}} \)	k₁为第1个瓦斯压力下的渗透率；\( {\partial k} \)为煤体渗透率变化量；\( {{\partial P}}_{{\mathrm{m}}} \)为瓦斯压力变化量
4	滑脱效应影响率^[49]	\( {{M}}_{{{\mathrm{k}}}}{=}\dfrac{{k}{–}{{k}}_{{0}}}{{k}} \)	k为试验渗透率；k₀为绝对渗透率
5	渗透率损失率^[50]	\( {{L}}_{{k}}{=}\dfrac{{{k}}_{{0}}{–}{{k}}_{{1}}}{{{k}}_{{0}}} \)	\( {{k}}_{{0}} \)为初始渗透率；k₁为应力加载至第1个应力点对应的渗透率
6	渗透率损伤率^[50]	\( {{D}}_{{k}{1}}{=}\dfrac{{{k}}_{{1}}{–}{{k}}_{{1}{x}}}{{{k}}_{{1}}} \)	k₁为加载过程第1个应力点对应的渗透率；k_1x为卸载过程应力恢复至第1个应力点对应的渗透率
注：变量含义仅适用于对应公式。

Table6

拟合类型	拟合参数	拟合度R²
指数函数	\( {k}={153.82{\mathrm{exp}}(- 4.10}{{P}}_{\text{m}}{)+2.79} \)	0.99
幂函数	\( {k}={4.38}{{P}}_{\text{m}}^{{0.69}} \)	0.87
二次函数	\( {k}={2.20}{{{P}}_{\text{m}}^{{2}}{-8.47}{P}}_{\text{m}}{+10.92} \)	0.95

Table7

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应力路径	拟合类型	拟合公式	拟合度R²
轴向应力加载过程	指数函数	\( {k}{=2.56}{{\mathrm{exp}}(}{-}{{\sigma }}_{{{\mathrm{e}}}}{/39.52)}{-}{1.45} \)	0.99
	幂函数	\( {k}{=}{4.25}{\sigma }_{{{\mathrm{e}}}}^{{–0.90}} \)	0.98
	二次函数	\( {k}{=}{6.32}{\sigma }_{{{\mathrm{e}}}}^{{2}}–{{0.06}\times {{10}}^{{-}{4}}{\sigma}}_{{{\mathrm{e}}}}{+1.10} \)	0.99
轴向应力卸载过程	指数函数	\( {k}{=}{1.43}\times {{10}}^{{5}}{\mathrm{exp}}(-{{\sigma}}_{{{\mathrm{e}}}}{/0.54)+0.45} \)	0.91
	幂函数	\( {k}{=}{0.91}{\sigma }_{{{\mathrm{e}}}}^{{–0.30}} \)	0.76
	二次函数	\( {k}{=}{0.01}{\sigma }_{{{\mathrm{e}}}}^{{2}}{–}{{0.10}{\sigma}}_{{{\mathrm{e}}}}{+1.03} \)	0.82