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Date:2021-10-10 View:37

Fatigue damage of oil well drill pipe

Fatigue damage is the most common type of drill pipe damage. There are three basic types of fatigue damage:

Tensile failure of oil well drill pipe

Tensile failure often occurs during the whole process of pulling and tightening the stuck drill pipe. When the tensile force exceeds the yield limit, a "fine neck" deformation will occur at the weaker part of the drill pipe wall or at a small cross section. If the pull-up resistance exceeds the limit compressive strength just now, the drill pipe will be torn off. Tensile failure generally occurs at the upper end of the drill string. Because the upper drilling tool has to bear the force and the net weight of the drill string.

Oil well drill pipe vibration, bending damage

When the drill pipe string reaches the critical speed ratio, it will cause the drill pipe to vibrate. This vibration usually causes the drill pipe to bend, excessively damage, quickly damage and fatigue damage. Especially when the drill pipe produces two kinds of vibrations (both node vibration and spring pendulum type vibration) overlapping. The critical speed ratio changes with the length of the drilling tool, the specifications of the drilling tool, the specifications of the drill collar and the borehole size.

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