物探冲旋钻头破岩机理仿真研究

Research on Rock Breaking Mechanism of Geophysical Prospecting Hammer Bit

冲旋钻井技术已广泛应用于油气资源勘探领域,但仍存在一些不足,比如钻具损坏严重、能量传递效率低、破岩效率有待进一步提高等。因此,有必要进一步揭示物探冲旋钻井中钻头与岩石的互作用机理,为优化设计冲旋钻头提供理论依据。利用显式动力学分析软件LS-DYNA建立了物探冲旋钻头破碎岩石的有限元模型,并进行了计算机仿真,得到了钻头中心齿、第2排齿、边齿、钻头端面的应力时程图和应力波在钻头中的传播图。仿真结果表明:钻头破岩过程中,各个牙齿的应力变化非常大,第2排齿的应力峰值最大,其次是中心齿,再次是边齿;钻头喷嘴处的应力远大于钻头中心端面和排屑槽的应力;应力波在钻头中传播,危险区域经历了从钻头尾部到钻头喷嘴再到牙齿的过程。

Percussion drilling has been widely used in oil and gas exploration,while there are still some problems,such as severe damages to drilling tools,low energy transfer efficiency and low rock breaking efficiency. Thus it is necessary to further reveal the hammer bit rock interaction mechanism in geophysical percussion drilling to provide theoretical basis for the structural optimization. Using explicit dynamic analysis software LS-DYNA,a finite element model of rock breaking for geophysical prospecting hammer bit is established. The stress-time curves of the centre teeth, second-row teeth and peripheral teeth, and the stress wave propagation in bit were obtained using simulation. Simulation results indicate that the stress of each tooth changed significantly during rock breaking. The stress of second-row teeth is the greatest, followed by the centre teeth, and then the peripheral teeth. The nozzles＇stress is much greater than that of the centre-head face or the junk slot. When the stress wave propagated in the bit, the hazardous area passed from drill bit to nozzles and then to teeth.