| 摘要 |
<p>A spiral ribbed aluminum drillpipe has an intermediate portion with a plurality of ribs spiraling along its length. These ribs have active faces that are exposed by recessed areas. The active faces define incut angles relative to the pipe's outer surface for actively engaging slime/sediment material along a borehole wall. Bearings rotatably disposed on the pipe have a greater diameter than the ribbed intermediate portion or any tool joints on the drillpipe so that the bearings engage the borehole wall. The pipe's body is preferably composed of a lightweight alloy, such as aluminum alloy, whereas the bearings are preferably composed of steel and have wear resistant coating or bands.</p> |
