复合冲击频率配合特性模拟研究

目前,对于传统的轴向冲击破岩和扭力冲击破岩机理的研究较多,而复合冲击钻井破岩机理的研究正处于起步阶段,且现有的研究成果极少。鉴于此,利用ABAQUS动力学冲击模块计算平台建立了PDC钻头单齿-岩石相互作用的动力冲击数值模型,考虑切削齿在钻压、转速、交变冲击扭矩和交变轴向冲击力等多个载荷的共同作用下,分析了复合冲击破岩方式、轴向冲击和扭向冲击频率配合方式、钻压等几个因素对复合冲击破岩效果的影响。研究结果表明:岩石单元内部拉应力与压应力破坏区域交替分布;冲击条件相同,且在轴向冲击频率为扭向冲击频率的1/2时,岩石破碎效率最高;如果冲击频率太小,而不能及时有效地破碎钻遇岩石,即发生黏滑振动;如果冲击频率太大,载荷作用时间太短,则破岩过程中冲击能量无法及时分配,冲击力微弱,因此,复合冲击频率配合数量关系存在一个冲击频率极值。复合冲击钻井技术破岩机理的研究为新型钻井工具的进一步开发和优化改进奠定了理论基础。

Simulation Study on Compound Percussion Frequency Matching Characteristics

There are many researches on the traditional axial impact rock breaking and torsional impact rock breaking mechanism.But researches on the rock breaking mechanism of compound percussion drilling are few and are still in infancy state.In view of this,the ABAQUS dynamic impact module calculation platform is used to establish the dynamic impact numerical model of the PDC single cutter-rock.Under the combined action of the multiple loads on the PDC cutter like WOB, RPM,the alternating impact torque, and the alternating axial impact force,the effects of compound percussion rock breaking mode,axial impact and torsional impact frequency matching method,and WOB on the compound percussion rock breaking effect are analyzed.The results show that the internal tensile stress and compressive stress failure area of rock unit are alternately distributed. Under the same impact condition,the maximum rock breaking efficiency is obtained when the axial impact frequency is 1/2 of the torsional impact frequency.Too low impact frequency could not timely break the rock,leading to stick-slip.While too high impact frequency results in insufficient impact time.The impact energy cannot be distributed in time,leading to weak impact force.Therefore,there is an extreme impact frequency value for the compound percussion frequency matching.The study on the rock breaking mechanism of compound percussion drilling technology lays a theoretical foundation for the further development and optimization of new drilling tools.