基于凝析气相变的凝析油聚集规律研究

Research of condensate accumulation based on phase change of gas condensate

在凝析气藏衰竭开发过程中,当压力低于露点压力时反凝析油会在井筒附近聚集,堵塞凝析气的渗流通道,降低气相有效渗透率,导致产能降低,且两相流动区和凝析油堵塞区将随着生产的延续不断向远井处扩展。根据Fevang和Whitson等对凝析油气的流动分区,利用物质平衡原理和拟稳态渗流理论,对凝析气藏衰竭开发过程中的3区变化规律进行了严格推导,得到凝析气藏衰竭开发过程的3区扩展模型。利用3区在凝析气藏中扩展和缩小的规律,能够准确预测凝析油气两相流动区和凝析油堵塞区变化规律,为正确评价凝析气井的产能提供理论依据。实例计算表明,新模型预测的3区扩展模型是正确的。

For condensate gas reservoirs producing below the dew-point pressure, condensate accumulates near wellbore, blocking flow channels of condensate gas and decreasing gas effective permeability and productivity. With the continuing of the production, two-phase flow area and condensate blocking area extend outwards. Based on the flow regimes division of Fevang, Whitson, et al, the extension models of the 3 zones in the condensate gas reservoirs under depletion development were derived using the material balance theory and the pseudosteady percolation theory. The alteration of the two-phase flow area and condensate blocking area can be accurately predicted with the models, providing theoretical basis for the reasonable evaluation of the condensate gas productivity. The case study proves the accuracy of the models.