钻头与井壁碰撞模型的建立及分析

钻井过程中 ,钻柱的振动使钻头与井壁产生的碰撞是钻头和钻柱早期失效的主要原因。通过建立钻头与井壁的碰撞模型 ,将碰撞简化为两个圆柱筒之间的碰撞 ,利用冲量定理和实验方法获得的钻头与井壁碰撞时的恢复系数及钻头碰撞前的速度 ,可计算出钻头与岩石碰撞后的速度和碰撞时产生的碰撞力。摸清钻头与井壁之间的碰撞规律 ,为有效预防钻头与钻柱的早期失效 ,预测井眼轨迹 ,有效提高钻井效率提供了理论依据

Model of impact between rock bit and wall of well

The impact between the rock bit and the wall of well caused by drillstring vibration is the main reason of early failure of the bit and the drilling string. A model of the impact tetween the bit and the wall of well is set up.The impact is simplified as an impact of two cylinders. According to the coefficient of restitution obtained from experiment and the speed of the bit before impact,the speed of the bit after impact and the impacting force can be worked out.By finding the law of the impact between the bit and the wall of well,approaches are available to preventing the early failure of the bit and drillstring and predicting the trajectory of the borehole and improving the drilling efficiency.