考虑井筒变质量流动的砾石充填水平井产能预测

Productivity prediction for gravel-packed horizontal well considering variable mass flow in wellbore

应用质量守恒和动量守恒原理推导砾石充填水平井井筒内变质量流动压降方程,并采用拟三维思想,将地层内流体在三维空间的流动分为水平面内的向垂直裂缝流和近井区域垂直平面内的径向流,建立油藏渗流模型。提出将井筒变质量流与油藏渗流耦合的数学模型及求解方法。结果表明:利用该模型计算的水平井产能与实测结果平均误差仅为3.79%,沿井筒流量分布计算值与生产测井值基本一致;越靠近水平井跟端,井筒内流体流速越大,加速度损失和摩擦损失越大,压力下降越明显;随着砾石充填层渗透率增加,产量先急剧增加,后趋于平稳,合理选择砾石充填层渗透率对提高水平井产能有重要意义。

According to the principle of mass and momentum conservation theorem,the pressure drop equations of variable mass flow in the gravel-packed horizontal well were derived.The fluid flow in 3-D space was divided into flowing towards vertical fracture in the horizontal plane and radial flowing in the vertical plane near the wellbore.Using pseudo-three dimensional idea,the reservoir seepage model was developed.The model coupling seepage in reservoir with variable mass flow in wellbore was established and the solving method was given.The results show that the calculated results of well production by this model have high precision and the average error with field data was only 3.79%.The calculated flow rate along wellbore is consistent with the logging derived flow rate.The smaller the distance from root end of wellbore,the greater the fluid velocity in wellbore,the acceleration loss,the friction loss and pressure drop.With the permeability of gravel-packed layer increasing,the production increases sharply,after stabilizing,so a reasonable choice for permeability of gravel-packed layer is important to improve horizontal well productivity.