基于实验和数值仿真的钻具防顶卡瓦结构优化

现有技术及装备中对预防钻具上顶的研究较少，目前没有一套成熟的装置能够解决钻具在溢流关井后高套压引起的上顶问题。设计的钻具防上顶装置能够有效解决这个问题，装置所用卡瓦在工作过程中承受较大夹持力，其齿尖易发生磨损，直接影响防上顶装置的锚定性能。运用有限元和室内实验相印证的方法对卡瓦工作过程进行分析，分析了牙前角、牙顶圆角和齿顶距等参数变化对钻具应力分布的影响，通过数值模拟得到钻具Mises应力、接触压力及钻具轴向滑移量的变化趋势，优化出牙前角60°、牙尖部截面形状为圆角，且半径0.3 mm时为最合理的防上顶卡瓦牙型，并通过室内实验进行了验证。研究结果对钻具防上顶装置的卡瓦结构优化设计提供了理论依据。

Optimization of Slips Structure for Preventing Upward Sliding of Drill Pipe Based on Experimental and Numerical Simulation

There are few researches on prevention upward sliding of drill pipe,which is caused by high casing pressure after well shut-in,mature equipment to solve the problem have remained elusive.This problem can be solved effectively by the drilling pipe anti-jacking device designed in this paper.The slips used in the device bear a large clamping force during the working process,and the tooth tip is prone to wear,which directly affects the anchoring energy of the anti-jacking device.Through laboratory test and numerical simulation,this paper analyzed the working process of the slips,and analyzed the parameters such as the tooth rake angle α,tooth top round chamfer R and slips tooth tip distance d,which affect the stress distribution on the drill pipe,meanwhile,we obtained the Mises stress distribution and contact stress distribution of the drillpipe,the change law of axial displacement with each parameter.The results indicated that the tooth rake angle α=60°and tooth top round chamfer R=0.3 mm is the most reasonable slips tooth type,and this conclusion was well verified by laboratory experiments.The research results provide a theoretical basis for the optimal design of the slips structure of the anti-jacking device.