聚焦于碰摩诱导的非规则形貌套管磨损分析

Analysis of Irregular Morphology Casing Wear Induced by Collision and Rub

由于钻磨铣作业管柱刚度低且受力情况复杂,发生涡动时不可避免会碰摩套管,诱导套管产生不连续、随机的磨损,降低井筒安全性。为研究碰摩磨损对套管安全性的影响规律,基于转子动力学理论建立了钻磨铣作业钻柱有限元动力学模型,得到钻柱涡动轨迹及钻柱涡动诱发的套管碰摩特征;同时建立了碰摩磨损体积计算模型,考察转速、钻压对碰摩诱导的套管磨损的影响规律;将碰摩磨损缺陷引入套管模型,采用应力集中比值分析碰摩磨损缺陷对套管承载性能的影响规律。研究结果表明:钻磨铣作业期间钻柱对套管的碰摩主要发生在下部钻具组合处,表现为不连续性碰摩和连续性碰摩2种形式;转速、钻压与碰摩磨损程度呈正相关关系;碰摩磨损缺陷的偏磨率、开口大小及数量会对套管承载性能产生不同的影响。研究结果可为由碰摩诱导产生的套管磨损分析及井筒完整性评价提供理论依据。

Due to the low stiffness and complex stress situation of the milling operation string,the casing is inevitability collided and rubbed when whirling motion occurs,inducing discontinuous and random wear of the casing,and reducing the safety of the wellbore.To study the influence of collision and rub wear on the safety of casing,based on rotor dynamics theory,a finite element dynamic model of the milling operation string was built to obtain the drill string whirling motion trajectory and the collision and rub characteristics of casing induced by drill string whirling motion.A collision and rub wear volume calculation model was built to investigate the influence of rotary speed and WOB on the casing wear induced by collision and rub.Finally,the collision and rub wear flaw was introduced into the casing model,and the stress concentration ratio was used to analyze the influence of collision and rub wear flaw on the bearing performance of the casing.The study results show that during the milling operation,the collision and rub of drill string on casing mainly occurs at BHA,manifested in two forms:discontinuous and continuous collision and rub.The rotary speed and WOB are positively correlated with collision and rub wear rate;and the eccentric wear rate,opening size and amount of collision and rub wear flaws would have different influences on the bearing performance of the casing.The study results provide a theoretical basis for analyzing casing wear induced by collision and rub and evaluating wellbore integrity.