基于煤岩割理正交各向异性的煤层气渗流模型研究

考虑煤岩面割理和端割理两个方向不同渗流性质,建立了煤岩割理正交各向异性数学模型,通过引入煤岩弹性模量折减系数有效地解决了渗透率模型中煤岩割理刚度较难确定的问题。基于该模型对鄂尔多斯盆地东部煤层单井产能进行了模拟计算,分析了割理渗透率正交各向异性系数、煤层厚度、煤层孔隙度和含气量等参数对煤层单井产能的影响规律。计算结果表明：煤层气单井产能随着渗透率正交各向异性系数、煤层厚度和含气量增加而增大,随着煤层孔隙度的增加而减小。

Coalbed Methane Seepage Model Study with the consideration of the Orthotropic Permeability of Coal Seam

According to the basis of the orthotropic physical properties of coal cleats and different seepage characteristics in the orientation of the face and butt cleats, the orthotropic permeability model of coalbed methane output forecasting is established. By introducing the elastic modulus reduction factor, the difficulty for the determination of the cleat stiffness is solved effectively. The numerical simulations of well in Ordos basin are carried out basing on the orthotropic permeability model. The calculating results are compared to verify the precision of the proposed model. The influences of the permeability orthotropic coefficient, thickness, porosity, gas content, and etc on the coalbed methane output forecasting are studied. The examples show that the gas rates increase with the increase of the permeability orthotropic coefficient,the thickness and gas content,whereas it decreases with the increase of porosity.