钻柱失效机理分析

阐明了定向钻井过程中，钻柱由于弯曲交变循环应力而造成的疲劳损伤是可以积累的，钻柱的寿命与疲劳损伤积累有关。对钻柱进行了动载力学分析和疲劳寿命预测，提出了相应的计算模型，可以计算钻柱组合中任意钻柱单元在钻井过程中所受的疲劳损伤，预测使用寿命。对钻柱的合理使用与监控以及预防钻柱失效具有较大的参考价值。

Failure Mechanism of Drill Strings

It is presented that during a directional well drilling, drill string is subject to fatigue damage because of alternating bending cyclic stress ,from which the damage may be accumulated and its fatigue life is related with the accumulation of fatigue damage A mechanic analysis of dynamic loading and a prediction of fatigue life are conducted on the drill string,a corresponding calculation model is established and a software is developed for the calculating program By using a software,the calculation of fatigue damage and prediction of its service life are performed for random drill string unit in the string assembly In contrast with the diagram recommended in API,the software's precision is improved, which is great valuable for reasonable application and monitoring of the drill strings and prevention of their failures