钻井液中钻柱振动分析

Analysis of vibration of drill string in drilling fluid

钻柱在钻井液中的振动一直是钻井中不能忽视的问题,它会造成钻柱的疲劳损害,缩短设备寿命,但同时也会给钻井施工带来意想不到的益处。在裸眼中钻柱与井眼之间因振动引起的碰撞还会使井眼直径过大或者形成椭圆形井眼,给后期的施工带来严重的影响,但是在水平井水平段施工或者大位移井及井斜很大的井中,钻柱振动可以适当减弱井底托压对钻井影响,也可提高井眼清洁度,减少沉砂,避免很多的复杂事故,如卡钻、钻进时扭矩出现剧烈的波动、摩阻加大、钻速变慢等。钻柱在井眼中振动的相关因素有附加质量系数和黏滞阻尼系数以及振动的固有频率。通过实验分析对振动因素的影响,提出优化建议,对以后钻井施工有指导意义。

Drilling string vibration in drilling fluid has been a problem that cannot be ignored in drilling, it will cause the drill string fa- tigue damage, reduce equipment life, but also will bring unexpected benefits to drilling construction. In naked wells, collision due to vi- bration between drill string and well borewill enlarge borehole diameter, or can form elliptical hole, which can bring great influences on late construction. But in the horizontal section of the horizontal well construction or large displacement wells and wells with large in- clined angle, the vibration of drilling string can properly reduce the bottom supporting effect on the drilling pressure, also can improve the hole cleaning, reduce the grit and avoid a lot of complex accidents. The correlation factors of the vibration of drill string in the well include the additional mass coefficient,the viscous damping coefficient and the natural frequency of the vibration. In this paper,the ex- perimental analysis were carried out on the influence of vibration factors, optimized suggestions were also put forward, and also has a guiding significance for future construction.