低渗透气藏渗流机理不同于常规气藏，尤其是束缚水饱和度较高的低渗透气藏存在启动压力梯度，目前低渗气藏的产能方程均将由启动压力梯度引起的启动压降视为一个与产量无关的常数，实践证明目前方程存在较大误差。为此，文章基于低渗透气藏非达西低速稳定渗流微分方程，推导出启动压降的表达式，分析得出启动压降并非为绝对常数，而与测试产量有关，并以修正等时试井为例分析了目前产能方程的误差；最后通过对启动压降进行定积分的近似求解，得出考虑启动压力梯度的低渗透气藏气井新的产能方程，提出相应的修正等时试井资料的处理方法，实际应用表明，所提出的产能试井分析新方法具有实用价值。

The flowing mechanism of a low permeability gas reservoir is different from a conventional gas reservoir, especially for that with higher irreducible water saturation the threshold pressure gradient exists. At present, in all the deliverability equation, the additional pressure drop caused by the threshold pressure gradient is viewed as constant, but this method has big error in the practical application. Based on the nonDarcy steady flow equation, the limited integral of the additional pressure drop is solved in this paper and it is realized that the additional pressure drop is not a constant but has something to do with production data, and a new deliverability equation is derived, with the relevant processing method for modified isochronal test data. The new deliverability equation turns out to be practical through onsite application.