煤层单相水非稳态渗流模型研究

为了得到排水过程中的非稳态渗流特征,通过相应的坐标变换,建立同时考虑各向异性及应力敏感现象的单相水非稳态渗流模型,采用近似解法并根据物质平衡原理,给出内边界定产、外边界无限大条件下的煤储层压力分布及动边界变化规律.算例分析表明:煤层排水过程中,压降漏斗以椭圆形式向外拓展,应力敏感性越强,井底流压和地层压力下降越快;初始渗透率和应力敏感系数的各向异性共同控制泄流面积的大小及形态.

Unsteady percolation model of water in coalbed

In order to get the unsteady-state flow characteristics,an unsteady flow model of water considering stress-sensitivity and anisotropy is established with coordinate transformation. The pressure distribution and the movement law of outer pressure boundary under the inner boundary of invariable output and infinite outer boundary are presented by using an approximate method and the material balance principle. The analysis results of cases show that in the draining water process of CBM wells,the pressure drop funnel extends outward in the form of ellipse in coal reservoir,the stronger the stress sensitivity of the reservoir,the more quickly the bottomhole pressure and formation pressure decline; the anisotropy of initial permeability and stress sensitivity coefficient controls the size and the shape of the discharge area of single well.