(1) Apply weight on bit;
(2) Ensure the necessary strength under compression conditions;
(3) reduce the vibration, swing, and beat of the drill to make the drill work smoothly;
(4) Control well inclination.

Drill collars are generally divided into three types: spiral drill collars, non-magnetic drill collars, and integral drill collars.

(1) The whole drill collar is a smooth thick wall round pipe, and the two ends are processed to connect the thread.
(2) The spiral drill collar processes 3 right-turn spiral grooves on the outer cylinder of the round drill collar to reduce the contact area with the well wall and effectively prevent the differential pressure sticking
(3) Non-magnetic drill collar is mainly used for monitoring in the oil drilling process, and the structure is the same as the whole drill collar. Non-magnetic drill collars are manufactured using N1310 low-carbon alloy steel, which is forged through rigorous chemical composition analysis. The mechanical properties of the material can be tested to ensure that the hardness, toughness, impact value and corrosion resistance meet the standards, with good low permeability and good machining properties.

In order to facilitate the trip work, the hanger groove and slip groove can be machined on the outer surface of the inside thread of the drill collar.

Implementation standard: SY5144-2007.API7-1