有效应力对煤吸附特性影响的试验研究

为了研究煤岩吸附特性受有效应力影响的机制，结合压汞试验所测定的孔隙率和孔径分布情况，利用自制的原煤等温吸附装置，分别在不同有效应力条件下对山西潞安煤样进行了CH4等温吸附试验。结果表明：①恒温条件下，随着有效应力的增加，煤对CH4吸附量呈下降趋势，气体压力越高时这种变化趋势越明显；②Langmuir方程吸附常数a与有效应力呈负相关关系、吸附常数b则呈正相关关系，分析认为这与原煤内部部分微孔隙封闭和化学势差变化有关；③根据试验数据拟合得出考虑有效应力影响的Langmuir方程形式，所得结果对于煤层气资源评价和开采具有较大的参考价值。

Experimental study of influence of effective stress on coal adsorption performance

In order to investigate the influence mechanism of effective stress on the adsorption property of coal, a series of isothermal adsorption experiments of coal from Lu’an coal mine are designed and conducted. Combining the porosity and pore size distribution law determined by mercury injection test and using the self-made testing apparatus, the difference of methane adsorption law are confirmed under the different effective stress conditions. The results show that: ①When temperature is constant, CH4 adsorption amount decreases as the effective stress increases; and the larger the gas pressure is the stronger such change tendency becomes. ②The Langmuir equation constant a has a negative correlation with effective stress and the constant b has a positive correlation with effective stress. It is related to the closure of a portion of micropores and the change of chemical potential difference. ③According to the fitting results of experiments, the Langmuir equation takes the influence of effective stress into account is proposed. The research results have some reference significance to the reservoir evaluation and development of coalbed methane.