Abstract: Cement slurry's rheological characteristic can be changed by application of physics fields for treatment such as magnetic field,electrostatic field and middle or high frequency electromagnetic field.Its apparent viscosity,plastic viscosity and fluid loss are reduced while its mobility and crushing strength are enhanced.Furthermore,if friction reducer and physics fields are used together,the amount of friction reducer may be decyesed.

Key words: drillstring, weight-on-bit, vibration, fluctuation, stability, rotary speed, frequency, parametrically excited system, dynamic bifurcation, vertical section, drilling parameters, working state

摘要： 基于弹性大变形理论,考虑到轴力沿钻柱轴线的变化及其对钻柱弯曲变形的影响等因素,将受自重作用的铅垂井段钻柱在波动钻压激励下的振动转化为一个参数激励系统,用Galerkin方法首次得到了描述此系统的Mathieu方程,并通过将方程的解展成富里叶级数的方法,得到了该振动系统的动力分岔值曲线及其所包围的动力不稳定区.当钻井作业参数落在动力不稳定区时,钻柱将发生破坏性振动.根据钻柱的物理与几何性质及钻柱的工作状态,首次推导出了参数激励系统分岔参数的计算公式,并据此开发了相应的程序模块.该模块可以根据钻井现场的实际情况,提供合理的转速和钻压等作业参数,以避开动力不稳定区,改善钻柱的工作状态,延长其工作寿命.

关键词: 钻柱, 钻压, 振动, 波动, 稳定性, 转数, 频率, 参数激励系统, 动力分岔, 铅垂井段, 工作参数, 工作状态