【摘要】 根据储层压力下降和煤基质收缩效应建立了渗透率变化数学模型,模型应用及参数敏感性分析结果表明:排采过程中,渗透率先减小后增加,并根据水平有效应力变化值将排采过程分为三个阶段;泊松比越大,水平有效应力变化值越趋向于增加,渗透率越趋向于衰减;极限吸附量和吸附常数越大,水平有效应力变化值越趋向于减小,渗透率越趋向于增加;实际排采时,在井底流压降至渗透率反弹点压力之前,要尽量减小排采强度,防止近井处渗透率快速下降阻碍排水降压,在降至渗透率反弹点压力之后,适当增大排采强度,使渗透率尽快反弹。更多还原

【Abstract】 Based on reservoir pressure drop and coal matrix shrinkage effect, a mathematic model was built for permeability variation. According to the application and sensitivity analysis of the model,it is concluded that,in CBM drainage,coal permeability increases firstly and then decreases,this process can be divided into three stages based on different value of effective horizontal stress change; when the Poisson ’s ratio increases, the effective horizontal stress intends to increase, when Langmuir volume and Langmuir constant increase, the effective horizontal stress tends to decrease; in CBM production,small drainage rate is recommended when reservoir pressure is larger than the pressure at permeability rebounding point and drainage rate shall be appropriately larger after reservoir pressure drops to the pressure at permeability rebounding point.更多还原