气体钻井中钻柱力学性能及冲蚀实验研究

由于在破岩过程中受到冲击，气体钻井中的钻柱产生了交变应力，而钻柱旋转加剧了交变应力的变化，同时气体携带岩屑对钻柱产生冲蚀，加速了钻柱的失效。钻柱主要失效形式为疲劳断裂，这跟钻柱所受应力大小及变化密不可分，因此，开展气体钻井过程中钻柱力学性能和冲蚀研究，掌握钻柱应力变化规律及岩屑对钻柱的冲蚀规律，是减小和防止钻柱失效的基础工作，对增加气体钻井过程中的安全性和降低钻井成本有十分重要的意义。通过使用一种已开发出的可同时模拟气体钻井钻具振动和冲蚀的装置，进行了不同钻具组合情况下，气体钻井钻柱同时受振动和冲蚀实验。实验结果表明，气体钻井过程中，配置扶正器将使钻柱所受交变应力值变化范围降低40% 以上，扶正器和减振器的配合使用将使交变应力值变化范围下降50%，因此，扶正器和减振器的配合使用，将大幅降低钻柱所受交变应力，并延长交变应力作用周期，从而降低钻柱失效的概率。

Experimental Research on Mechanical Properties and Erosion of the Drill String in Gas Drilling

The drill sting for the gas drilling is impacted in the process of crushing rock,so the alternating stress occurre.Alternating stress changes is aggravated by the rotating drill string,and the drill string is also erosion by debris,so the failure is accelerated.The main failure form of drill string is fatigue fracture,which is inseparable from the drill string,so the research on mechanical properties and erosion of the drill string in gas drilling,mastering the drill string stress change rules and erosion law of drill string are the basic work to reducing and preventing the drill string failure.This work has very important meaning for increasing the safety and reducing the cost in gas drilling.The drill string of gas drilling in the situation of vibration and erosion in the case of different combination drilling tools by using an experiment device which can simulate the situation is studied in this paper.The experiment shows that using centralizer will reduce the alternating stress value range up to 40%,and using centralizer and shock absorber at the same time will reduce the alternating stress value range up to 50%.The centralizer and the shock absorber used together will reduce the alternating stress greatly and extend the alternating stress function cycle,thus the probability of failure of the drill string will be reduced.