低渗油藏的两相相对渗透率计算方法

在考虑启动压力梯度的影响，以质量守恒方程为基础，得到了低渗油藏中计算水、油两相相对渗透率的方法，编制了相应的应用软件，并给出了两个实例进行应用说明．新方法与原有的ＪＢＮ 方法类似，主要区别是：在注入能力公式中加入启动压力梯度的影响，可以看作为ＪＢＮ 方法的推广．分析表明：①以束缚水饱和度下的油相渗透率为基准渗透率时，启动压力梯度不影响油相的相对渗透率，只影响水相的相对渗透率；②油相启动压力梯度增大时，油相相渗曲线不变，水相相对渗透率减小；③由于水相的启动压力梯度远小于油相，因此水相启动压力梯度的影响可以忽略不计．

A Method for Calculating the Relative Permeabilities of Water and Oil in Low Permeability Reservoirs

A method is deduced for calculating the relative permeabilities of oil and water in low permeability reservoirs, and the application software is also made for it. Two examples are given. Compared with JBN method, the advantage of this method is that the influence of starting pressure gradient is considered.It can be thought that the method is the popularization of JBN method. The analysis results shows that, (1) if the permeability of oil at irreducible water saturation is regarded as a critical permeability, starting pressure gradient has an effect only on the relative permeability of water, and has no effect on that of oil; (2) as the starting pressure gradient of oil increase, the relative permeability of water will decrease; (3) compared with the starting pressure gradient of oil,that of water is small, so the influence of the starting pressure gradient of water can be neglected.