| 摘要 |
<p>METHOD FOR IMPROVING CUTTINGS REMOVAL IN DRILLING DEVIATED WELLBORES A rotary drilling technique for improving cuttings removal and reducing packoff and differential pressure sticking tendencies of drill strings in deviated wellbores employs a number of jets of drilling fluid which emerge from the drill string preferably near the bit in a direction axially along the borehole away from the drill bit or at specific locations up the drill string where casing size increases because of the use of a liner. The jets may be arranged to emerge entirely axially up the borehole or with an additional, radial component of velocity also. Because packoff problems generally arise in the regions where the radial width of the annulus increases, the jets are to be provided in these regions in order to maintain linear fluid velocities as well as providing additional fluid volume in this region. The drilling tool comprises a tool joint with a number of angled, radial passageways pointing in a reverse direction uphole so that the emerging fluid jets have the required components of velocity.</p> |
