| 摘要 |
<p>Assembly system for improving rotary drilling operations comprises a weighting rod for connecting to a drilling pipe, having a female thread at one end as well as an annular groove of reduced dia. on its external surface near the threads at least at one end, the reduction of dia. being such that the Moment of Inertia is 50-80% of that of the initial right section of the rod.</p> |
