【摘要】 目前模拟煤层气开采过程数学模型主要分为三类 ,即经验模型、平衡吸附模型和非平衡吸附模型 ,其中非平衡吸附模型是一种较为完善 ,能客观反映煤层气开采动态的双孔隙模型。不少文献已经建立了煤层气扩散渗流非平衡吸附数学模型 ,但往往存在模型假定过于简化、个别关键参数难于获取以及采用IMPES方法求解可能引起不收敛现象等不足之处。文章发展了一个煤层气储层模拟器用来模拟煤层甲烷气的开采过程 ,该模拟器采用双重介质网格系统的气水两相数学模型 ,考虑了煤层气从基质表面进入开采井筒所经历的解吸、扩散和渗流三个过程。基于Fick、Darcy定律以及连续性方程建立了数学模型 ,对数学模型进行差分离散数值求解 ,方程中系数项和产量项采用显式处理 ,求取参数及基质与割理系统质量交换量采用隐式格式处理求解。此外 ,编写了程序源码建立计算机模型 ,最后进行实例分析对比 ,验证了该模型的可靠性和合理性更多还原

【Abstract】 At present,the mathematical models of simulating coalbed methane production behavoir may be mainly devided into three types,i.e.empirical model,equilibrium adsorption model and non-equilibrium adsorption model,in which the non-equilibrium adsorption model can objectively describe coalbed methane production behavoir,being a relatively perfect dual-porosity reservoir model.The non-equilibrium adsorption mathematical models of describing coalbed methane diffusion percolation flow have been found in many literatures,in the models,however,there are some shortcomings,such as oversimplified assumptions,single key parameter’s being obtained difficultly and non-convergence’s being caused in adopting IMPES method for solving,etc.In the paper,a coalbed methane reservoir simulator developed for simulating methane producing process is a diphase (gas-water) mathematical model of applying dual grid system,and three processes,i.e.desorption,diffusion and percolation flow,undergone by coalbed methane from matrix surface into wellbore are considered in the simulator.On the basis of Fick’s law.Darcy’s law and continuty equation,a mathematical model was established and numerically solved by use of differential discrete method;the coefficient term and production term in the equation were explicitly dealt with;and the implicit format treatment and solution were adopted to acquire the parameters and the amount of mass exchange of matrix-cleat system.In addition,the program source code was written;and through analyzing and contrasting an example,it is proved that the simulator is reliable and reasonable.更多还原