海上完井封隔器新型锚定卡瓦咬入套管分析

Analysis of New Anchoring Slips of Packer for Offshore Completion

基于海上φ244.5 mm(9 5/8in)套管井内封隔器应用要求,对卡瓦进行受力分析,计算卡瓦咬入套管的深度。运用ANSYS软件建立卡瓦咬入套管二维有限元模型,研究80°、90°和100°等3种牙型角的卡瓦咬入套管深度和等效应力分布规律。研究结果表明,在相同的坐封压力、验封压力和承载情况下,80°牙型角卡瓦咬入套管深度最小,90°牙型角卡瓦咬入套管深度最大,大于90°咬入套管深度减小;随着卡瓦承受载荷的增大,卡瓦等效应力增大,验封过程中卡瓦应力均已超过材料屈服强度。卡瓦设计时除了需要优化其本身结构参数外,对选材和热处理也有特殊要求,应采用整体淬火+回火+表面渗碳处理,这样可将卡瓦表面硬度和强度提高近2倍。

According to the requirements of packers applied in offshore 0244.5 mm （95//ss in） cased hole, the stress analysis of slip is made and the biting depth of the slip is calculated. A two-dimensional finite element model for slip biting into casing is established by using ANSYS software to study the biting depth and equivalent stress distribution of the slip with the thread angle of 80°, 90° and 100°. The results show that under the same setting pressure, sealing test pressure and bearing load, the biting depth of the slip is the minimum with the thread angle of 80° and reaches the maximum with the thread angle of 90~. But the biting depth will decrease when the thread angle is larger than 90°. With bearing load increases, the equivalent stress of the slip increases. The slip stress has exceeded the material yield strength during the sealing test. Thus, in addition to structural parameters optimization, material selection and heat treatment also need to be concerned. Integral quenching ＋ tempering ＋ surface earburizing treatment are proposed to improve the slip surface hardness and strength nearly 2 times to meet onsite operational requirements.