低渗透气藏低速非线性渗流数值模拟研究

大量实验表明，低渗气藏流体在低速渗流时不仅要克服启动压力梯度，而且还受到气体滑脱效应的影响。基于低渗气藏的这一渗流特征，建立了考虑启动压力梯度和气体滑脱效应的低渗低速非线性渗流数学模型及其有限差分方程，并编制数值模拟软件，对比研究了四种情况：(1) 不考虑启动压力梯度和气体滑脱效应；(2) 仅考虑启动压力梯度；(3) 仅考虑气体滑脱效应；(4) 考虑启动压力梯度和气体滑脱效应。数值模拟结果表明：情形(3)的累计产量最高，情形(4)次之，情形(1)第三，情形(2)最低。这一结果说明启动压力梯度和气体滑脱效应对低渗气藏的生产影响很大，由此证明了模型的正确性和适用性。

LOW-SPEED AND NON-LINEAR FLOW THROUGH POROUS MEDIA NUMERICAL SIMULATION FOR LOW-PERMEABILITY GAS RESERVOIR

A lot experiment indicates that low-speed flow through porous media in low-permeability gas reservoir should overcome not only threshold pressure gradient but also slippage effects.Abase on the characteristics，a non-linear flow through porous media mathematical model and finite difference equation with considering threshold pressure gradient and slippage effects are established and numerical simulator is developed，then four conditions are studied and compared，1，without considering threshold pressure gradient and slippage effects，2，only considering threshold pressure gradient，3，only considering slippage effects，4，considering both threshold pressure gradient and slippage effects.The numerical simulation results show that the cumulative gas production of condition 3 is the best，condition 4 is the second，condition 1 is the third，and the second is at the least.Therefore，threshold pressure gradient and slippage effects impact a big effect on the production of low-permeability gas reservoirs，so the model is validable and applicable.