瓦斯吸附热效应作用下渗透率回弹和恢复演化

doi:10.12068/j.issn.1005-3026.2025.20230306

摘要/Abstract

摘要：

气体吸附/解吸所释放/吸收热量对煤层渗透率回弹和恢复特性演化存在显著影响，基于热-流-固(THM)多物耦合理论探究了单/多重瓦斯吸附热因素耦合作用下渗透率回弹和恢复现象在时间尺度上的演化特征，并进一步获取吸附热效应对煤层气开采特性的影响.结果表明：单一因素作用下，渗透率回弹和恢复时间与吸附热强度呈正相关趋势，同样其对Langmuir常数的响应特征与前者类似，且当吸附性能参数超过临界值后趋于稳定；多因素耦合作用下，瓦斯吸附热强度对渗透率回弹和恢复现象时间尺度的控制作用表现为促进，而空间尺度上则不易受吸附热影响.此外，若未考虑瓦斯吸附热效应将会高估回弹和恢复带来的瓦斯流量增量.

关键词: 煤层气, 渗透率回弹, 渗透率恢复, 瓦斯吸附热效应, 抽采量

Abstract:

The thermal quantity released/absorbed during gas adsorption/desorption significantly influences the evolution of permeability rebound and recovery in coal seams. Based on the thermo-hydro-mechanical （THM） coupling theory， this study investigates the temporal evolution of permeability rebound and recovery under single/multiple gas adsorption thermal effects and further assesses their impact on coalbed methane （CBM） extraction. Results indicate that under a single-factor influence， permeability rebound and recovery time exhibit a positive correlation with adsorption heat intensity， and its response to Langmuir’s constant is characterized similarly to the former and tends to stabilize when the adsorption performance parameter exceeds the critical value. Under multi-factor coupling， adsorption heat enhances permeability rebound and recovery on the temporal scale while the spatial scale is less susceptible to adsorption heat. Furthermore， neglecting adsorption thermal effects may lead to an over-estimation of the gas production increase induced by permeability rebound and recovery.

Key words: coalbed methane, permeability rebound, permeability recovery, gas adsorption thermal effects, extraction capacity

中图分类号:

TD 712

刘正东, 林晓松, 白刚, 孙晨. 瓦斯吸附热效应作用下渗透率回弹和恢复演化[J]. 东北大学学报（自然科学版）, 2025, 46(5): 103-112.

Zheng-dong LIU, Xiao-song LIN, Gang BAI, Chen SUN. Evolution of Permeability Rebound and Recovery Under the Influence of Gas Adsorption Thermal Effects[J]. Journal of Northeastern University(Natural Science), 2025, 46(5): 103-112.

图/表 16

图1 现场测试数据与模拟结果的匹配结果

Fig.1 Matching results between field test data and simulation results

图2 渗透率回弹与恢复时间示意图

Fig.2 Schematic diagram of permeability rebound and recovery time

表1 数值模型所需参数[10,14,20-22]

Table 1 Parameters required in the numerical simulation model

参数	值	参数	值
煤层初始压力p₀/MPa	6.6	吸附时间τ/s	844 345
杨氏模量E/MPa	2 713	CH₄摩尔质量M_c/(kg·mol^-1)	0.016
基质杨氏模量E_m/MPa	8 139	CH₄动力黏度μ/Pa·s	1.08×10^-5
煤层压缩系数C_f/MPa^-1	0.139 2	CH₄导热系数 $λ$ _g/(W·m^-1·K^-1)	0.031
煤层密度ρ_c/(kg·m^-3)	1 250	煤骨架导热系数 $λ$ _s/(W·m^-1·K^-1)	0.191
气体常数R/(J·mol^-1·K^-1)	8.314	CH₄等量吸附热q_st/(J·mol^-1)	2 100
极限吸附量n_m/(m³·t^-1)	20	Langmuir 压力常数b/MPa^-1	1
煤骨架比热容c_s/(J·kg^-1·K^-1)	1 350	Langmuir 应变常数ε_L	0.126 6
泊松比v	0.35	CH₄比热容c_L/(J·kg^-1·K^-1)	2 160
初始渗透率k₀/cm²	4.935×10^-12	内部膨胀系数f	0.1
初始裂隙率ϕ_f	0.005	初始孔隙率ϕ_m	0.05

表1 数值模型所需参数[10,14,20-22]

Table 1 Parameters required in the numerical simulation model

参数	值	参数	值
煤层初始压力p₀/MPa	6.6	吸附时间τ/s	844 345
杨氏模量E/MPa	2 713	CH₄摩尔质量M_c/(kg·mol^-1)	0.016
基质杨氏模量E_m/MPa	8 139	CH₄动力黏度μ/Pa·s	1.08×10^-5
煤层压缩系数C_f/MPa^-1	0.139 2	CH₄导热系数 $λ$ _g/(W·m^-1·K^-1)	0.031
煤层密度ρ_c/(kg·m^-3)	1 250	煤骨架导热系数 $λ$ _s/(W·m^-1·K^-1)	0.191
气体常数R/(J·mol^-1·K^-1)	8.314	CH₄等量吸附热q_st/(J·mol^-1)	2 100
极限吸附量n_m/(m³·t^-1)	20	Langmuir 压力常数b/MPa^-1	1
煤骨架比热容c_s/(J·kg^-1·K^-1)	1 350	Langmuir 应变常数ε_L	0.126 6
泊松比v	0.35	CH₄比热容c_L/(J·kg^-1·K^-1)	2 160
初始渗透率k₀/cm²	4.935×10^-12	内部膨胀系数f	0.1
初始裂隙率ϕ_f	0.005	初始孔隙率ϕ_m	0.05

图3 物理模型及其边界条件

Fig.3 Physical model and boundary conditions

表2 单因素条件下模拟方案

Table 2 Simulation scheme under single factor condition

方案	n_m/(m³·t^-1)	b/MPa^-1	q_st/(J·mol^-1)
1	20	1	2 100
	40
	60
2	20	1	2 100
		2
		3
3	20	1	2 100
			2 600
			3 100

图4 不同等量吸附热条件下监测点处渗透率演化规律

Fig.4 Permeability evolution patterns at monitoring points under different isochoric adsorption heat conditions

图5 渗透率回弹和恢复时间与等量吸附热的关系(a)—回弹时间; (b)—恢复时间.

Fig.5 Relationship between permeability rebound and recovery time and isochoric adsorption heat

图6 不同等量吸附热条件下监测点A处的回弹值

Fig.6 Rebound value at monitoring point A under different isothermal adsorption conditions

图7 A点处渗透率随时间变化(a)—极限吸附量; (b)—Langmuir压力常数.

Fig.7 The change of permeability with time at point A

图8 渗透率回弹时间演化(a)—极限吸附量； (b)—Langmuir压力常数.

Fig.8 Permeability rebound time evolution

图9 渗透率恢复时间演化(a)—极限吸附量; (b)—Langmuir压力常数.

Fig.9 Permeability recovery time evolution

表3 多因素耦合条件下模拟方案

Table 3 Simulation scheme under multiple factor coupling condition

方案	n_m/(m³·t^-1)	b/MPa^-1	q_st /(J·mol^-1)
1	20	1	2 100
2	40	2	4 200
3	60	3	6 300

图10 监测点A处渗透率演化差异

Fig.10 Differences in permeability evolution at monitoring points A

图11 监测点A解吸量及应变量差异(a)—解吸量; (b)—应变.

Fig.11 Differences in desorption and strain at monitoring point A

图12 不同监测点处回弹和恢复时间差异(a)—回弹时间; (b)—恢复时间.

Fig.12 Differences in rebound and recovery time at different monitoring points

图13 考虑与未考虑吸附热效应抽采量差异

Fig.13 Difference of extraction capability with and without adsorption thermal effect

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