同层分支水平气井不稳定产能分析

多分支水平井能够数倍地增加储集层泄油气面积,有效提高气井产量。基于气体不稳定渗流理论,应用Newman 乘积原理和Green 函数,得到与x 轴平行的水平气井的压降解析解,结合坐标旋转,推导出与x 轴成α 角的水平气井不稳定产能方程,进而运用压降叠加原理,导出分支水平气井不稳定产能预测模型。分析结果表明:(1)气藏中分支水平井产量随分支数的增加而增加,但随着分支数的增加各分支间干扰作用加强,产量增加幅度减少,分支数存在一个最优值;(2)根据最优分支数,得到其产量随时间的增加而不断减小,后趋于一定值,流动达到拟稳态。

Analysis of Transient Deliverability of Multi-Branch Horizontal Gas Wells

Using multi-branch horizontal wells can greatly increase the drainage area of reservoirs and effectively raise gas production. Based on gas transient flow theory, the pressure drop analytical solution of the horizontal gas well in parallel with x-axis is concluded according to Newman's product principle and Green function. Combined with rotation of axes, the transient deliverability equation for horizontal gas well is derived with α angle to the x-axis. And then the transient deliverability forecasting model for multi-branch horizontal gas wells is presented based on the principle of pressure drop superposition. The analysis result shows that: (1) the production of multibranch horizontal wells in gas reservoirs increases with the increasing of number of the branches, but interference effect strengthens, production growth range decreases when the number increases, indicating that there is an optimal value of the number of branches; (2) according to the optimal number of branches, the production is declining with time, followed by tending to a certain value, and the flow reaches pseudo-steady state.