弧角型PDC钻头切削齿布齿模式仿真分析

钻头在钻进复杂非均质地层时，由于其冠部形状的限制，钻头各部位切削齿受力不均匀，局部切削齿受到较大的冲击载荷，导致钻头发生“涡动”现象。为了解决上述问题，提出“多级力平衡”的切削齿周向布齿方案，通过建立全尺寸钻头破岩有限元仿真模型，分析顺时针、逆时针以及“多级力平衡”3种周向布齿模式下切削齿及钻头的受力特性。模拟结果表明:相对于顺时针和逆时针周向布齿，“多级力平衡”布齿模式下各刀翼载荷分布比较均匀，钻头的稳定性和攻击性均得到较大改善，钻头的破岩效率提高28%以上；顺时针布齿模式下钻头的侧向力最大，其稳定性相对最差；逆时针布齿模式下钻头的钻压最大，其攻击性相对较差，并且钻头的破岩效率最低。上述研究成果能够为指导PDC钻头切削齿的周向布齿设计提供理论依据。建议今后加强“多级力平衡”周向布齿模式下切削齿载荷沿钻头径向分布规律方面的研究，以指导防涡稳定PDC钻头的优化设计。 

Simulation of the cutter arrangement pattern of the arc PDC drill bit

When drilling in a complex heterogeneous formation, due to the limitation of bit crown shape, the cutters of each part of the bit are subjected to non-uniform force, and the cutters at the local location are subjected to large impact load, which lead to the occurrence of bit vortex. In order to solve the problem, a “multi-level force balance” cutter circumferential arrangement scheme is proposed. By establishing the rock breaking finite element simulation model of the bit, the mechanical characteristics of the cutter and the bit under three circumferential cutter distribution modes(clockwise, counterclockwise and “multi-level force balance”) are analyzed. Simulation results show that comparing with the clockwise and counterclockwise circumferential cutter arrangement modes, the load distribution of each blade is more uniform under the “multi-level force balance” cutter arrangement mode, the ability and aggression of the bit are improved, and the rock-breaking efficiency of the bit is improved by more than 28%, for the clockwise circumferential cutter arrangement mode, the lateral force of the bit is the highest and the stability of the bit is the worst; while for the counterclockwise circumferential cutter arrangement mode, the weight on bit is relatively higher, and the bit is less aggressive, the rock-breaking efficiency is the lowest. The above research results can provide a theoretical basis for the design of circumferential cutter distribution of the PDC bit. It is suggested that, in the future, the research on the cutter load distribution along the radial of the bit under the “multi-level force balance” cutter circumferential arrangement scheme should be strengthened, so as to guide the optimal design of the anti-vortex stable PDC bit.