冲-切混合钻头工作动态分析与破岩效率研究

Working Dynamics of Impact Scraping Hybrid Drill Bits Analysis and Research on Rock Breaking Efficiency

针对现有钻头在深部复杂难钻地层的破岩效率低的问题,本文提出冲击-刮切分离式混合钻头,冲击齿与PDC齿相互独立工作。通过有限元分析得出冲击齿先对岩石预损伤,弱化岩石性质,再依靠PDC刮切岩石,钻头通过冲击-刮切的方式切削地层,仿真结果表明,冲切方式的破岩的最大轴向力和最大切削力都有所减小,平均轴向力减小34.93 N,降低12.1%,平均切向力减小26.09 N,降低9.1%,降低PDC齿破碎比功,从而提高混合钻头的破岩效率。根据混合钻头切削齿运动特点,运用复合坐标系统分析切削齿与钻头的几何关系,进而建立切削齿的速度、加速度以及动力学方程,通过MATLAB软件来模拟混合钻头的切削齿破碎岩石的动态过程,并得到混合钻头的井底形貌以及切削齿的切削截面、切削体积、切削力等参数,为新型混合钻头的研发提供了理论基础。

In order to improve the drilling efficiency of bit drilling in poor-drillability formation,the authors of this article put forward,a cutting-percussion hybrid bit,the fixed-cutting units and impact-crushing units of which are mutually independent and are able to work in parallel.Through finite element analysis,it is concluded that the impact teeth will degenerate the material and mechanical properties of the rock,and that the polycrystalline diamond compact cutters will remove the pre-damaged rock with relatively low energy consumption,The simulation results show that the maximum axial force and maximum cutting force of rock breaking by punching are reduced,the average axial force is reduced by 34.93 N,12.1%,and the average tangential force is reduced by 26.09 N,9.1%,thus improving the rock-breaking efficiency of the bit.Moreover,on the basis of the geometrical and kinematical characteristics of the hybrid bit,geometrical relationships between the teeth and the bit body,as well as the kinematics and kinetics of the teeth,are studied in compound coordinate systems.Furthermore,by programming in MATLAB,the rock-breaking process of the hybrid bit is simulated and the simulation results consist of the bottom-hole profile,cutting area,cutting volume,and cutting force of the cutters,providing the theoretical basis for the research and development of the hybrid bit.