围压对高阶煤瓦斯吸附规律影响的LNMR实验研究

LNMR experimental study on influence of confining pressure on gas adsorption laws of high rank coal

为了深入了解围压对高阶煤瓦斯吸附规律的影响,以焦作赵固矿高阶煤为研究对象,利用低场核磁共振(LNMR)系统与围压加载系统,开展了高阶煤在不同围压下的瓦斯吸附实验。结果表明:高阶煤瓦斯吸附过程中,T2谱出现3个特征峰(吸附峰、游离峰、自由峰),其微小孔发育、中大孔不发育、渗透性差。同一围压下,随着吸附时间增加,吸附量呈现先增大后保持不变的趋势,吸附增量逐渐降低,能在7 h内达到吸附平衡。随着围压增大,吸附饱和量、吸附初速度均逐渐降低,达到吸附平衡所需要的时间增加;围压增大对中大孔孔隙结构具有明显的收缩作用,而对微小孔孔隙结构影响并不明显。

In order to understand the influence of confining pressure on the gas adsorption law of high-rank coal,the high-rank coal of Zhaogu Mine in Jiaozuo was taken as the research object and the low-field nuclear magnetic resonance(LNMR)system and the confining pressure loading system were used to carry out gas adsorption experiments of high-rank coal under different confining pressures.The results showed that three characteristic peaks(adsorption peaks,free peaks,and free peaks)appeared in the T2 spectrum during the gas adsorption process of high-order coal.It was found that the micro-pores of high-rank coals are well developed,the medium-large pores are not developed,and the permeability is poor.Under the same confining pressure,with the increase of the adsorption time,the adsorption amount increased first and then remained unchanged,the adsorption increment gradually decreased and reached the adsorption equilibrium within 7 h.With the increase of confining pressure,the adsorption saturation and initial adsorption velocity decreased gradually,and the time needed to reach adsorption equilibrium increased.The increase of confining pressure has a significant contraction effect on the pore structure of medium and large pores,but has no obvious effect on the pore structure of small pores.