裂缝性低渗透气藏垂直裂缝井产能分析

Productivity Analysis of Fractured Wells in the Low Permeability Naturally Fractured Gas Reservoir

利用椭圆流动模型和质量守恒法,建立并求解了考虑启动压力梯度影响的裂缝性低渗透气藏有限导流垂直裂缝井不稳定渗流的数学模型。绘制了产能动态曲线,同时分析了启动压力梯度、裂缝导流能力、弹性储能比和窜流系数对产能动态曲线的影响。分析结果表明:裂缝性低渗透气藏有限导流垂直裂缝井产能动态曲线可以划分为裂缝流动阶段、窜流阶段和总的系统径向流动阶段。启动压力梯度越大,产能越低;裂缝导流能力越大,产能越高;弹性储能比越大,产能越高;窜流系数越大,发生窜流的时间越早。这对深入认识裂缝性低渗透气藏有限导流垂直裂缝井的生产动态具有重要意义。

By using the elliptical flow model and the law of mass conservation, the mathematical model of unsteady percolation for wells with finite conductivity vertical fractures considering threshold low permeability naturally fractured gas reservoir was developed, and type curves of produ pressure gradient in the ctivity performance were drawn and analyzed. Influences of threshold pressure gradient, fracture conductivity, storativity ratio and interporosity flow coefficient were analyzed. Analytic results show that the type curve of productivity performance can be divided into three periods, namely, the period of fracture flow, the period of interporosity flow, the period of total radial flow. The bigger the threshold pressure gradient is, the lower the productivity is. The bigger the fracture conductivity is, the higher the productivity is. The bigger the storativity ratio is, the higher the productivity is. The bigger the interporosity flow coefficient is, the earlier the interporosity flow happens. These are of significance for in-depth understanding of the producing performance of wells with finite conductivity vertical fractures in the low permeability naturally fractured gas reservoir.