带旋转导向工具的底部钻具组合横向振动特性研究

为了提高旋转导向工具的井眼轨迹控制效果及作业安全性，研究了带静态推靠式旋转导向工具底部钻具组合（RSBHA）的横向振动特征。静态推靠式旋转导向工具通过控制3个导向翼肋的驱动压力实现井眼轨迹控制，可以将其等效为偏心距和偏心方位角已知的偏心稳定器；建立RSBHA的三维小挠度静力学模型，基于加权余量法确定RSBHA在钻压作用和井壁约束下的空间构形，获得上切点的位置；以上切点到钻头的距离作为横向振动的有效长度建立有限元模型，利用振型叠加法求解RSBHA的横向振动响应，分析工作参数和结构参数对其横向振动的影响。算例结果发现:转速约为138 r/min时， RSBHA的动态位移在距钻头8.20，18.10，24.60和31.60 m处较大；钻压对RSBHA最大弯曲应力的影响较小；偏心距和偏心方位角对RSBHA横向振动特性的影响较大，对于某些特定的偏心距和偏心方位角，RSBHA最大弯曲应力会明显增加。研究结果表明，结构参数和工作参数对RSBHA的横向振动影响较大，应对其进行优化设计，以确保旋转导向工具的应用效果和钻井作业安全。 

Research on Lateral Vibration Characteristics of Bottom Hole Assembly with Rotary Steerable Tool

To improve the borehole trajectory control effect and operation safety of rotary steerable tools, the analysis of the lateral vibration characteristics of rotary steerable bottom hole assembly (RSBHA) was conducted. A static push-the-bit rotary steerable tool can control borehole trajectories through its driving force produced from its three pads, and thus it can be regarded as an eccentric stabilizer with known eccentricity and eccentric azimuth. In this work, a three-dimensional statics model of RSBHA with small deflection was constructed to determine the spatial configuration of RSBHA under the weight on bit and the constraints of borehole wall by the weighted residual method, and thus to obtain the upper tangential point. Then, a finite element model was built, taking the distance between the upper tangential point and the bit as the effective length for lateral vibration. The lateral vibration responses of RSBHA could be elicited using the mode superposition method, and analysis of the influence of working and structural parameters on its lateral vibration could be made. The calculation results showed that when the rotary speed was around 138 r/min, the dynamic displacement of RSBHA was greater in the distances of 8.20 m, 18.10 m, 24.60 m, and 31.60 m away from the bit. The weight on bit had little impact on the maximum bending stress of RSBHA, while the eccentricity and eccentric azimuth had a greater impact on the lateral vibration characteristics, and the maximum bending stress would obviously increase for certain eccentricity and eccentric azimuth. The research shows that working and structural parameters have great influence on the lateral vibration of RSBHA, which should be optimized to ensure the proper application and operation safety of rotary steerable tools.