高阶煤吸附孔结构特征及其对甲烷吸附能力的影响

张黎明; 林健云; 司磊磊; 赵琼祥; 王沉; 武国鹏

doi:10.13272/j.issn.1671-251x.2024040083

高阶煤吸附孔结构特征及其对甲烷吸附能力的影响

doi: 10.13272/j.issn.1671-251x.2024040083

1.
贵州大学矿业学院，贵州贵阳　550025
2.
贵州兴安煤业有限公司，贵州兴义　561504

基金项目: 贵州省科技支撑计划项目（黔科合支撑〔2023〕一般482）；国家自然科学基金资助项目（52364010，52174072）。

详细信息

作者简介:
张黎明（1990—），女，四川巴中人，实验师，硕士，主要研究方向为煤矿瓦斯灾害防治，E-mail：lmzhang1@gzu.edu.cn

中图分类号: TD712
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- 被引次数: 0
出版历程
- 收稿日期: 2024-04-24
- 修回日期: 2024-07-23
- 网络出版日期: 2024-08-01

Features of adsorption pore structure in high-rank coal and its influence on methane adsorption capability

1.
Mining College, Guizhou University, Guiyang 550025, China
2.
Guizhou Xing'an Coal Industry Co., Ltd., Xingyi 561504, China

摘要

摘要: 孔隙结构对煤层吸附甲烷的能力有显著影响，但目前对高阶煤吸附孔结构特征及其对甲烷吸附能力的影响研究较少。以贵州兴安煤业有限公司糯东煤矿高阶煤样为研究对象，采用低温N₂吸附和低温CO₂吸附试验，结合分形理论研究了高阶煤吸附孔的孔隙结构特征，并通过高压等温甲烷吸附试验，分析了煤储层物性、孔隙结构特征和分形维数对甲烷吸附能力的影响。结果表明：① 高阶煤储层孔隙形态较为单一，多数为两端开放的平行板孔和狭缝型孔，微孔在煤的孔隙结构中占主导地位，其孔体积和孔比表面积占比均大于98%，为气体的富集提供了空间。② 以不同孔径段的孔体积占比为权重计算高阶煤孔隙的综合分形维数，微孔分形维数在综合分形维数中占主导地位；煤样孔隙结构具有明显的分形特征，孔隙非均质性较强。③ Langmuir模型能很好地描述高阶煤的吸附行为，煤储层物性、孔隙结构和分形维数对甲烷吸附能力影响显著，Langmuir体积与最大镜质体反射率、镜质组含量、灰分含量和水分含量呈线性正相关关系，与惰质组含量呈线性负相关关系；Langmuir体积与吸附孔的孔比表面积和孔体积均呈线性正相关关系，Langmuir体积与分形维数呈弱线性关系。研究结果可为黔西南地区高阶煤层气勘探开发及煤矿瓦斯灾害防治提供理论指导。
- 高阶煤 /
- 吸附孔 /
- 孔隙结构 /
- 气体吸附 /
- 孔径分布 /
- 分形特征
Abstract: The pore structure has a significant impact on the capability of coal seams to adsorb methane. But there is currently limited research on the features of adsorption pore structure in high-rank coal and its influence on methane adsorption capability. Taking the high-rank coal samples from Nuodong Coal Mine of Guizhou Xing'an Coal Industry Co., Ltd. as the research object, low-temperature N₂ adsorption and low-temperature CO₂ adsorption experiments are conducted. Combined with fractal theory, this paper studies the pore structure features of high-rank coal adsorption pores. Through high-pressure isothermal methane adsorption experiments, the influence of coal reservoir properties, pore structure features, and fractal dimension on methane adsorption capability is analyzed. The results show the following points. ① The pore morphology of high-rank coal reservoirs is relatively simple, mostly consisting of parallel plate pores and narrow slit pores with open ends. Micro pores dominate the pore structure of coal, with pore volume and pore specific surface area accounting for more than 98%, providing space for gas enrichment. ② The method calculates the comprehensive fractal dimension of high-rank coal pores based on the proportion of pore volume in different aperture segments, with micropore fractal dimension dominating the comprehensive fractal dimension. The pore structure of coal samples has obvious fractal features and strong heterogeneity of pores. ③ The Langmuir model can describe the adsorption behavior of high-rank coal. The physical properties, pore structure, and fractal dimension of coal reservoirs have a significant impact on methane adsorption capability. Langmuir volume is linearly positively correlated with maximum vitrinite reflectance, vitrinite content, ash content, and moisture content. It is linearly negatively correlated with inertinite content. The Langmuir volume is linearly positively correlated with the pore specific surface area and pore volume of the adsorption pores. The Langmuir volume is weakly linearly correlated with the fractal dimension. The research results can provide theoretical guidance for the exploration and development of high-rank coalbed methane and the prevention and control of coal mine methane disasters in southwestern Guizhou.
- high-rank coal /
- adsorption pore /
- pore structure /
- gas adsorption /
- pore size distribution /
- fractal features

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图 1 低温N₂吸附/解吸等温线

Figure 1. Low temperature N₂ adsorption/desorption isotherm

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图 2 不同煤样的低温CO₂吸附试验结果及孔径分布特征

Figure 2. Low temperature CO₂ adsorption experiment results and pore size distribution features of different coal samples

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图 3 FHH模型分形拟合

Figure 3. Fractal fitting of frenkel halsey hill(FHH) model

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图 4 V−S模型分形拟合

Figure 4. Fractal fitting of V-S model

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图 5 分形维数与最大镜质体反射率、显微组分的关系

Figure 5. Relationship between fractal dimension and the maximum vitrinite reflectance or maceral

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图 6 甲烷吸附等温线

Figure 6. Methane adsorption isotherm

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图 7 甲烷吸附性能与煤储层物性的关系

Figure 7. Relationship between methane adsorption performance and physical properties of coal reservoirs

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图 8 甲烷吸附性能与吸附孔结构特征的关系

Figure 8. Relationship between methane adsorption performance and pore structure features

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图 9 甲烷吸附性能与分形维数的关系

Figure 9. Relationship between methane adsorption performance and fractal dimension

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表 1 煤样基础参数

Table 1. Basic parameters of coal samples

煤样	R_o,max/%	镜质组/%	惰质组/%	壳质组/%	水分/%	灰分/%	挥发分/%	固定碳/%	煤类
糯东1号	2.57	87.00	12.80	0.20	0.64	14.74	8.30	77.60	无烟煤
糯东2号	2.68	93.00	6.80	0.20	0.88	28.83	11.81	61.99	贫煤
糯东3号	2.62	89.00	10.70	0.30	0.58	14.37	8.54	77.79	无烟煤

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表 2 低温N₂吸附试验煤样孔比表面积分布特征

Table 2. Distribution features of pore specific surface area of coal samples for low temperature N₂ adsorption experiment

煤样	平均孔径/nm	BET孔比表面积/（m²·g⁻¹）	孔比表面积/（m²·g⁻¹）			孔比表面积占比/%
煤样	平均孔径/nm	BET孔比表面积/（m²·g⁻¹）	＜10 nm	10～100 nm	＞100 nm	＜10 nm	10～100 nm	＞100 nm
糯东1号	7.949	1.293	1.145	0.147	0.001	88.55	11.37	0.08
糯东2号	6.057	1.695	1.575	0.118	0.002	92.92	6.96	0.12
糯东3号	9.700	0.534	0.450	0.083	0.001	84.27	15.54	0.19

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表 3 低温N₂吸附试验煤样孔体积分布特征

Table 3. Distribution features of pore volume of coal samples for low temperature N₂ adsorption experiment

煤样	BJH孔体积/（10⁻³ cm³·g⁻¹）	孔体积/（10⁻³ cm³·g⁻¹）			孔体积占比/%
煤样	BJH孔体积/（10⁻³ cm³·g⁻¹）	＜10 nm	10～100 nm	＞100 nm	＜10 nm	10～100 nm	＞100 nm
糯东1号	2.373	1.208	1.132	0.033	50.91	47.70	1.39
糯东2号	2.232	1.320	0.850	0.062	59.14	38.08	2.78
糯东3号	1.245	0.452	0.768	0.025	36.31	61.68	2.01

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表 4 低温CO₂吸附试验煤样孔隙结构参数

Table 4. Pore structure parameters of coal samples for low temperature CO₂ adsorption experiment

煤样	孔比表面积/ （m²·g⁻¹）	孔体积/ （10⁻³ cm³·g⁻¹）	峰值点孔径/nm
糯东1号	190.520	61.900	0.524
糯东2号	146.755	51.415	0.548
糯东3号	146.943	48.145	0.599

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表 5 不同煤样吸附孔的孔隙结构参数

Table 5. Pore structure parameters of adsorption pores of different coal samples

煤样	孔体积/（10⁻³ cm³·g⁻¹）			总孔体积/ （10⁻³ cm³·g⁻¹）	孔比表面积/（m²·g⁻¹）			总孔比表面积/ （m²·g⁻¹）
煤样	0.3～1.5 nm	1.5～10 nm	10～100 nm	总孔体积/ （10⁻³ cm³·g⁻¹）	0.3～1.5 nm	1.5～10 nm	10～100 nm	总孔比表面积/ （m²·g⁻¹）
糯东1号	61.900	1.208	1.132	64.240	190.520	1.145	0.147	191.812
糯东2号	51.415	1.320	0.850	53.585	146.755	1.575	0.118	148.448
糯东3号	48.145	0.452	0.768	49.365	146.943	0.450	0.083	147.476

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表 6 不同煤样的分形维数

Table 6. Fractal dimension of different coal samples

煤样	10～100 nm孔径段（低温N₂吸附）		1.5～10 nm孔径段（低温N₂吸附）		0.3～1.5 nm孔径段（低温CO₂吸附）		综合分形维数D_z
煤样	D₁	R²	D₂	R²	D₃	R²	综合分形维数D_z
糯东1号	2.489	0.825	2.651	0.995	2.453	0.998	2.457
糯东2号	2.562	0.876	2.758	0.987	2.476	0.999	2.483
糯东3号	2.647	0.676	2.506	0.996	2.492	0.999	2.494

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表 7 甲烷吸附拟合结果

Table 7. Fitting results of methane adsorption

煤样	R_o,amx/%	V_L/（cm³·g⁻¹）	P_L/MPa	R²
糯东1号	2.57	25.534	1.703	0.995
糯东2号	2.68	32.590	1.371	0.994
糯东3号	2.62	28.314	1.198	0.996

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