射孔水平井产能分段数值计算

水平井开采时流入剖面不均匀，传统的产能解析公式或恒生产指数的计算方法难以准确预测其产能。假设地层均质，将射孔完井水平井筒分为多个井简单元段，采用拟三维思想，把流体在三维空间的流动分为垂直裂缝流、近井区径向流和孔眼汇聚流，并考虑地层伤害的影响，建立井简单元段的油藏渗流模型。根据孔眼注入对水平井筒中流体流动的影响，将井筒压力损失分为摩擦损失和加速损失两部分，基于质量、动量守恒原理，建立井筒流动压力损失模型。将油藏渗流与井筒流动耦合计算，开发了应用软件，井壁流入剖面计算结果表明，从水平井筒末端到跟端，井壁注入量逐渐增大；水平井产能计算结果与油井实际产量吻合较好。图1表2参14

A segmentally numerical calculation method for estimating the productivity of perforated horizontal wells

Owing to the non-uniform inflow profile,it was difficult to estimate the productivity of horizontal wells accurately by traditional analytical equations or calculation methods with constant production index.The well is partitioned into many segments on the assumption of homogeneous formation.The whole three-dimension flow is divided into three parts using the pseudo-three-dimension method: flow from infinite boundary into a vertical fracture,radical flow around the well bore,and convergent flow through perforations.Taking the influence of formation damage into account,a correlation equation between reservoir flow rate and pressure difference is obtained for each segment.According to the influence of perforation inflow on the main flow,the pressure drop along the horizontal well is attributed to friction and acceleration losses.A general pressure-drop expression is established based on the principles of conservations of mass and momentum.The resulting models,coupled together,are validated by the close match between numerical calculation results and field data.The calculation results also show that the perforation-influx rate increases gradually from the toe to the heel of the horizontal well bore.