BZ油田窄河道油藏产能预测方法及应用

Productivity prediction method and application of narrow channel reservoir in BZ oilfield

为研究窄河道油藏河道边界对产能的影响,将河道边缘等效为平行不渗透边界,应用镜像反映法结合势的叠加原理,推导出窄河道油藏定向井产能公式,并利用分流量方程得到窄河道油藏比采油(液)指数计算公式,以此为基础,利用油田典型相渗曲线,得到不同含水阶段比采油(液)指数理论图版。结果表明:河道宽度对产能的影响较大,受河道边界的制约,油井供给方向减少,在相同情况下,窄河道油藏比采油指数低于常规整装油藏;随着河道宽度的减小产能逐渐降低,且降低幅度越来越大;当河道宽度为300 m时,比采油指数为平面径向流的84%,当河道宽度减小至100 m时,比采油指数仅为平面径向流的50%。实际应用证实,新方法整体误差在5%以内,能准确地评价窄河道油藏产能。

In order to study the influence of channel boundary on productivity in narrow channel reservoir,the channel edge is equivalent to parallel impermeable boundary.The productivity formula of directional well in narrow channel reservoir is derived by using image reaction method combined with potential superposition principle,and the specific oil recovery(liquid)index formula of narrow channel reservoir is obtained by combining partial flow equation.On this basis,the theoretical charts of oil recovery(liquid)index at different water cut stages are obtained by using typical relative permeability curves.The results show that the channel width has a great influence on the productivity.Restricted by the river boundary,the oil well supply direction decreases.Under the same conditions,the specific oil recovery index of narrow channel reservoir is lower than that of conventional packaged oil reservoir;with the decrease of channel width,the production capacity gradually decreases,and the reduction range is more and more large;when the channel width is 300 m,the specific oil recovery index is 84%of the plane radial flow when the degree is reduced to 100 m,the specific oil recovery index is only 50%of the plane radial flow.The practical application shows that the overall error of the new method is less than 5%,and the productivity of narrow channel reservoir can be evaluated more accurately.