滑块捞矛井下退出的实践与力学原理分析

以多年的滑块捞矛应用经验为基础，通过在打捞状态下对滑块、矛杆受力情况的分析，推导出了鱼腔内壁对滑块的压力与钻具对捞矛的拉力之间的函数关系式，以及倒扣或捞矛退出时，鱼腔内壁对滑块的切向摩擦力引起的扭矩与钻具对捞矛的拉力之间的函数关系式，得出通过减小捞矛拉力可以减小鱼腔内壁对滑块的压力和切向摩擦力，继而减小静摩擦扭矩，探讨了滑块捞矛井下退出的规律，为滑块捞矛的井下退出方法及操作给出了建议。

Practice and analysis of mechanical principles for the down hole exiting of the sliding block spear

On the basis of sliding block spear application experiences for many years, according to stress analysis on the sliding block and spear rod in fishing situation, the functional relation formula between the acting force of the fish cavity wall to the sliding block and the pull of drilling tools to fishing spear is presented. And the functional relation formula between the torque caused by the tangential friction of the fish cavity wall to the sliding block and the pull of drilling tools to fishing spear is also obtained when back-off or spear exiting. Through the above analysis, we come to the conclusion that the pressure and tangential friction of the fish cavity wall to the sliding block could be decreased by reducing the spear tension followed by downsizing of the static friction torque which illustrates the mechanical principles for the down hole exiting of the sliding block spear. This paper gives a brief introduction of the method and proposal on the down hole exiting about sliding block spear.