减振器安装位置对钻柱纵向振动影响的研究

从2004年至2005年初,在塔里木油田共发生了6起石油减振器断裂失效事故,其中花键筒母扣根部断裂占了4起,油缸母扣根部断裂1起,芯轴断裂1起.针对上述事故,通过研究建立减振器安装位置不受限制、钻杆和钻铤长度可任意变化的整体钻柱纵向振动分析数学模型,确定了该模型的计算方法;拟定出计算用钻具组合及计算用井深;由计算机模拟分析得到在不同转速和减振器在不同安装位置情况下的计算值,由此得出结论:减振器安装在钻头上方不同的位置,可达到不同的减振效果和变化的钻头破岩冲击动载,进而确定出减振器的最佳安装位置;减振器安装在最佳位置,减振效果将提高几倍至十几倍,同时在不加大钻压的情况下可提高钻头的破岩能力.减振器最佳安装位置的钻柱新组合在塔里木油田大北3井现场试验获得成功,表明其研究具有广阔的应用前景.

Influence of Shock Absorber Installation Position on the Drill String Longitudinal Vibration

6 petroleum shock absorber breaking accidents happened from 2004 to the beginning of the 2005 in Tarim oil field, in which, there were 4 times of flower bond box thread root breaking, 1 cylinder box thread root breaking and 1 mandrel breaking. In view of the above accidents, the authors of the paper establishe the analytical mathematical model of integral drill string longitudinal vibration in which the installation position of the shock absorber is not limited and the length of the drill rod and the drill collar is flexible, figure out the calculation method of the model, draw up the drill string assembly and the well depth used in the calculation, obtain the calculation value by computer simulation at different rotational speeds and different installation positions of the shock absorber. So the authors deduce the conclusion: the different installation positions of the shock absorber on the bit can get different damping effects and variable rock breaking dynamic loads. When the shock absorber is at the optimum installation position which is determined by the damping effect and the rock breaking dynamic load, the shock absorber effect can be enhanced from several to more than 10 times and the ability of rock breaking can be enhanced on the condition that it doesn't add drill pressure. The new drill string assembly with the optimum installation position of shock absorber is successful in the Da Bei 3 well belonging to Tarim oil field, which indicates that the research has wide application prospect.