井下封堵球密封副密封性能理论分析

Theory Analysis on Sealing Property of Downhole Ball Sealer

封堵球密封副是石油钻采施工中常用的井下工具密封形式,目前其设计缺乏理论指导。建立密封副接触应力(比压)和接触宽度的理论模型和有限元模型,分别采用理论计算方法和有限元模拟方法分析几何参数和材料特性对密封副密封性能的影响规律。结果表明:在一定的施工工况下,井下封堵球的密封性能主要受球座锥面半锥角以及材料特性的影响;采用小半锥角设计可以同时增大密封比压和接触宽度,而选用较高弹性模量的封堵球材料在提高密封比压的同时却减小了接触宽度,因此,当以提高密封副密封性能为目标进行优化设计时,应选用较小的半锥角,同时选择合适弹性模量的封堵球材料,以达到密封效果最优。采用理论模型和有限元分析对封堵球密封副密封性能的分析结果相近。

Ball sealer is a kind of sealing method commonly used in petroleum downhole operation. However at the design is short of theory guide. Theory model and finite element analysis （FEA） model for predicting the sealing present specific pressure and contact width were built. The effects of geometry parameters and ball material on sealing property were ana- lyzed, by using separately the theoretical calculation method and FEA method. The result shows that, under certain opera- tion conditions, the sealing property of ball sealer is mainly depended on seat angle and material properties. Both sealing specific pressure and sealing contact width can be increased by smaller seat angle. The sealing specific pressure can be in- creased by higher elastic modulus of material of ball sealer, but the sealing contact width is decreased. Therefore, for the purpose of improving sealing effect, smaller seat angle and certain materials with suitable elastic modulus of the ball sealer should be chosen. The results obtained by theory model analysis to the sealing performance of ball sealer are similar as that by FEA model.