水平井变孔密分段射孔井筒压降计算模型

A Model for Calculating the Borehole Pressure Drop for Variable Perforation Density and Segmental Perforation in Horizontal Wells

射孔是水平井完井的主要方式,由于流体在水平井筒内的流动为变质量流,在水平井筒内必然因流体的流动而引起压力损失,主要包括摩擦压力损失、加速压力损失以及混合压力损失。以渗流理论和流体力学相关知识为基础,考虑地层流体和井筒流体的相互耦合作用以及现场的实际需要,提出了变孔密分段射孔的概念,推导出了水平井变孔密分段射孔的井筒压降模型,并分析了孔眼密度变化对水平井井筒压降的影响,为水平井新型完井方式的井筒压降计算提供了理论依据。

Perforation is one of the major means of horizontal well perforation.Because the fluid flowing in the wellbore is variable mass flow,pressure loss would be caused by borehole flowing,which includes friction pressure loss,acceleration pressure loss and mixed pressure loss.Based on the knowledge related with the filtration theory and fluid mechanics,the concept of variable perforation density and segmental perforation is proposed in consideration of the coupling of formation fluid with borehole fluid and field demands.A model is established for calculating borehole pressure drop for variable perforation density and segmental perforation in horizontal wells and the influence of perforation density variation on pressure drop in horizontal wells is analyzed.A theoretical basis is provided for calculating the pressure drop in the new horizontal well completion.