Analysis of Irregular Morphology Casing Wear Induced by Collision and Rub
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 cas-ing,and reducing the safety of the wellbore.To study the influence of collision and rub wear on the safety of cas-ing,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 colli-sion and rub wear flaw on the bearing performance of the casing.The study results show that during the milling op-eration,the collision and rub of drill string on casing mainly occurs at BHA,manifested in two forms:discontinu-ous 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 differ-ent 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.
milling operationworkoverdrill string whirling motioncollision and rubirregular morphol-ogycasing wear
万方数据
维普
