Drill Collar

Drill Collar

The drill collar is located at the bottom of the drill string and is the main component of the bottom hole assembly. Its main features are large wall thickness (typically 38-53mm, equivalent to 4-6 times the wall thickness of drill pipe), and high gravity and stiffness. In order to facilitate the tripping operation, the external surface of the internal thread of the drill collar can be machined with elevator slots and slip grooves.