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The difference between drill collars and drill rods

release time：2023-12-19

source： network

The drill collar is attached to the drill pipe and plays a role in overall weighting to prevent deviation. The inner diameter of the drill collar is smaller than that of the drill pipe and the weight is larger than that of the drill pipe. During the drilling process, the drilling pressure is formed by the weight of the drill string (connected by the drill pipe), so the lower part of the drill string is subjected to compressive stress. When drilling, the drilling pressure value is generally greater than the stable critical value of the drill string, so the lower compressed part of the drill string will bend under its own weight. A bent drill string will cause alternating stress during rotation, leading to fatigue failure of the drill string. In order to reduce the degree of fatigue damage, bending stress should be reduced. This requires minimizing the length of the compression section and increasing its rigidity as much as possible. Therefore, the compressed part at the lower end of the drill string does not use drill rods and instead uses drill collars.

The role of petroleum drill rods

Precautions for using non-magnetic drill collars

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The role of petroleum drill rods

Precautions for using non-magnetic drill collars

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