上击器的震击动载荷计算

应用弹性动力学分析方法， 在合理假设的基础上， 建立了震击作用动力学模型。模型将上击器震击解卡过程分为储能阶段、震击前阶段、震击阶段和震击后阶段。根据该动力学模型， 对现场某直井进行了实例计算， 结果表明， 在上击器震击解卡过程中， 只有作用在卡点的震击力才是真正起作用的震击动载荷， 如果该动载荷小于粘卡力， 则难以解卡。上击器震击时产生的震击力与上提拉力的比值不是固定值， 而是随钻柱结构变化而变化。一般而言， 上击器越靠近卡点， 解卡效果越好。

Calculation of jarring dynamic load of top jars

A dynamic model for jarring action is set up based on a rational assumption and by using the elastic dynamic analysis method. According to this model, the course of jarring and stuck freeing of a top jar is divided into four stages, and an example of calculation is given. The calculated result shows that, in the course of stuck freeing by means of top jars, it is the jarring force acted on the stuck point that functions as jarring dynamic load, if this dynamic load is smaller than the sticking force, it is difficult to carry out stuck freeing successfully. The ratio of the jarring force and pulling force changes with variation of the structure of drill stem, and the closer the top jar from the stuck point, the better the effect of stuck freeing.