煤层气自然解吸的煤体结构控制研究

Study on Coal Mass Structural Controlling of CBM Natural Desorption

基于典型区块柿庄煤田和安阳煤田大量实测含气量地面解吸阶段数据,运用常压下自然解吸扩散模型1和模型2推算的综合扩散系数方程,对比分析了自然解吸特征。研究结果显示,煤体结构决定其自然解吸特征。柿庄煤田煤样煤体结构较为完整,煤样解吸时间长,在3个月左右,解吸速率曲线表现为"两段式",解吸稳定阶段较长,衰减阶段不明显;安阳煤田煤体结构破碎,煤样解吸时间短,解吸时间在1个半月左右,解吸速率曲线表现为"三段式",即初始快速解吸阶段,稳定解吸阶段和衰减阶段。模型1和模型2计算的两个煤田的综合扩散系数总体随时间增加而减小,安阳煤田煤样综合扩散系数要大于柿庄煤田煤样综合扩散系数,且综合扩散系数表现出区域性,同一区域样品的综合扩散系数最终收敛在一起。

Based on a mass of measured CBM content data during surface desorption stage from typical blocks of Shizhuang and Anyang coalfields, using natural desorption diffusion models 1 and 2 computative comprehensive diffusion coefficient equation under normal pressure, contrastively analyzed natural desorption features. The result has shown that the coal mass structure dictated the natural desorption features. The coal mass structure of coal samples from Shizhuang coalfield is more complete, coal sample desorption time longer（about 3 months）, the desorption rate curves appear as＂two sector type＂, stable desorption stage longer, attenuation stage not clear.Anyang coalfield coal mass structure is broken, coal sample desorption time shorter（about 1.5 months）, desorption rate curves appear as＂three sector type＂, namely initial fast desorption stage, stable desorption stage and attenuation stage. Models 1 and 2 computed comprehensive diffusion coefficients of two coalfields decreasing along with time increasing as a whole, the coefficients of Anyang coalfield are larger than that of Shizhuang coalfield and shown as regional, comprehensive diffusion coefficients from same region finally convergence together.