Research Article
Study of Radial Vibration Impact on Friction and Torque of Rotary Drill String
Table 1
Section parameters of different joints models.
| Tool model | Section parameters | Major radius a (×10−3m) | Minor radius b (×10−3m) | Ratio of major radius to minor radius of the joint elliptical section |
| Common joint | 16 | 16 | 1 | Drill pipe | 1617 joint | 17 | 16 | 1.0625 | Friction | 1618 joint | 18 | 16 | 1.125 | Reduction joints | 1619 joint | 19 | 16 | 1.1875 |
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