煤层钻孔瓦斯流量的数值模拟

Numerical simulation of the gas flow quantity from boreholes in coal seam

煤层瓦斯流动是一个复杂的非线性物理过程,为定量模拟钻孔瓦斯流量,在分析煤层瓦斯流动基本特征的基础上,把吸附瓦斯的解吸视为游离瓦斯渗流的连续分布源,建立了煤层瓦斯流动的数学模型。通过数学变换,确定了煤层瓦斯流动数学模型的基本方程和定解条件。运用有限元方法对煤层瓦斯流动方程进行了求解,编制了FORTRAN解算程序。介绍了煤层钻孔瓦斯流量数值模拟的工程实例,将数值模拟结果与实测结果进行了对比,分析了偏差产生的原因。研究结果表明,数值模拟准确反映了煤层瓦斯流动基本规律,能够定量预测煤层钻孔瓦斯流量。

Gas flowing in coal seam belongs to a complex nonlinear physical problem. In order to simulate the gas flow quantity from boreholes, a kind of mathematical model for gas flow is set up on the basis of looking on desorbing gas as the continuous source of the infiltration of dissociative gas. Through mathematical conversion, the basic equation and its stable answer conditions of the model are obtained. Drawing on the equal parameter quadrilateral finite element method,a FORTRAN program is edited to solve the gas flow equation. An engineering example is introduced and the values of simulation and in-site measurement are compared to each other to analyze the cause of the warp. The result shows that the numerical simulation has truly reflected the basic law of gas flow and can predict gas flow quantity from boreholes in coal seam.