有效应力对不同阶煤渗透率影响的差异性分析

 通过不同阶煤储层渗透率应力敏感性实验,对比分析了有效应力对不同阶煤渗透率影响的差异。结果显示,在相同有效应力变化范围内,低阶煤渗透率下降幅度大于中、高阶煤;低、高阶煤渗透率变化较中阶煤更符合指数函数变化规律;低有效应力阶段,低阶煤渗透率损害系数、应力敏感系数大于中、高阶煤;相同有效应力下,低阶煤割理压缩系数大于中、高阶煤;不同煤阶割理压缩系数随有效应力增加呈现下降趋势,不应将其视为常数。应力敏感性评价参数拟合结果显示,中、低阶煤渗透率损害系数、割理压缩系数符合指数函数变化规律,高阶煤渗透损害系数、割理压缩系数符合线性函数变化规律;不同阶煤渗透率应力敏感系数均符合指数变化规律。

Influence of effective stress on permeability of different rank coals

Based on the stress sensitivity experiments of various rank coals, the influence of the effective stress on the permeability of different rank coals is studied. It is shown that in the same range of the effective stress variation, the decrease of the low-rank coal permeability is larger than that of the medium-rank and high-rank coals; The permeability variations of the low-rank and high-rank coals more consistently follow an exponential law than the medium-rank coal; In the low effective stress range, the damage coefficient of the permeability and the stress sensitive coefficient of the low-rank coal are greater than those of the medium-rank and high-rank coals; Under the identical effective stress, the cleat compressibility of the low-rank coal is greater than that of the medium-rank and high-rank coals; The cleat compressibility decreases with the increase of the effective stress, and it is not constant. Fitting results of evaluation parameters of the stress sensitivity show that the damage coefficient of the permeability and the cleat comperssibility of the low-rank and medium-rank coals follow an exponential law, but for the high-rank coal, they follow a linear function; the stress sensitive coefficient of various rank coals follows an exponential law.