偏轴钻具在窿9井轨迹控制中的应用分析

针对偏轴钻具在窿9井中的轨迹控制问题,采用非线性动力学分析方法,综合考虑钻具与井壁的不确定性边界条件、井底对钻头的反向激励、钻柱的屈曲等力学要素,建立了偏轴钻具组合的动力学模型,对模型进行了求解,获得了钻头运动轨迹。计算结果表明,原有钻井参数下,偏轴钻具组合的钻头多在第四象限运动,使切削该方位井底岩石的力度加大,即钻头将朝向该方向偏斜,从而使井斜增加;调整钻井参数后,显著提高了偏轴钻具的防斜能力,也提高了钻头运动的平稳性。

Application and Analysis of Offset-axes Assembly in Trajectory Control in Well Long 9

In light of the trajectory control problem with offset-axes assembly in Well Long 9,the dynamic model of offset-axes assembly was established adopting the nonlinear dynamic analysis which took into consideration the indeterminate boundary conditions of the assembly and the sidewall,the bottomhole reverse excitation to the drill bit and the drill stem buckling.The model was solved and the movement path of the bit was obtained.The calculation shows that under the original drilling parameters the bit of the assembly tends to move within the fourth quadrant,causing the force become greater which cuts the bottomhole rocks of the direction.In other words the bit deflects to the direction so as to increase hole deviation.The anti-deflection capacity of the assembly has been improved remarkably after regulating drilling parameters and the stability of the bit movement has also been improved.