The difference between drill pipe and drill collar
The drill collar is located at the lower part of the drill string and is the main component of the lower drill assembly. Its main feature is that the wall thickness is large (generally 38~53mm, which is equivalent to 4~6 times the wall thickness of the drill pipe), and it has greater gravity and rigidity. Drill collars are generally divided into 3 types: auger collars, non-magnetic drill collars, and integral drill collars.
Drill pipe is a steel pipe with a thread at the end, which is used to connect the surface equipment of the drilling rig and the drilling and grinding equipment or bottom hole device at the bottom of the well. The purpose of the drill pipe is to transport the drilling mud to the drill bit and together with the drill bit raise, lower or rotate the bottom hole device.
Difference: The drill collar is thicker than the drill pipe wall, and the weight per unit length is heavier. The lower part of the drill collar is connected with the drill bit, and the upper part is connected with the drill pipe. The functions are similar. The drill pipe mainly transmits motion and power. The drill collar is stronger than the drill pipe and directly drives the drill bit to work.