修正的低渗透气藏产能方程

在低渗透气藏开发过程中，由于启动压力梯度、应力敏感的存在，使得气体的渗流不符合经典的达西定律。在考虑启动压力梯度、应力敏感和滑脱效应的综合影响基础上，对气体的流速方程进行了修正，并结合渗流力学基本原理得到修正的低渗透气井产能方程。应用修正产能公式对某气田的实际数据进行了计算，得到如下结论：应力敏感的存在将使气井的产能大幅度下降，最大可下降14%；启动压力梯度的存在将使气井的产能下降，不过下降幅度较小；由于气体黏度远小于油，故低渗透气井中应力敏感对产能的影响比启动压力梯度的影响要大；黏度越大启动压力梯度对产能的影响越大。建议低渗透气藏开发中必须充分考虑应力敏感的影响。

The modified deliverability equation of low permeability gas reservoirs

The gas percolation is inconsistent with the Darcy law in the development of low permeability gas reservoir because of existence of starting pressure gradient and stress sensitivity. Based on considering the comprehensive influences of starting pressure gradient, stress sensitivity and slippage effect, gas flow velocity equation is modified and the improved deliverability equation of low permeability gas reservoir is given in combination with the basic theory of seepage mechanics. It is drawn a conclusion after calculating the actual data of a certain gas field by use of the modified deliverability equation that the existence of stress sensitivity forces gas well deliverability to decrease sharply by maximum 14% while the existence of starting pressure gradient also makes it decrease but to a smaller extent. So, the effect of stress sensitivity on deliverability is bigger than that of starting pressure gradient on deliverability in low permeability gas well because gas's viscosity is far less than oil's and the larger the viscosity is, the bigger the influence of starting pressure gradient on deliverability is, which suggests that the influence of stress sensitivity should be taken into full consideration in the development of low permeability gas reservoirs.