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

(1) The integral drill collar is a smooth thick-walled round tube with connecting threads processed on both ends.

(2) The spiral drill collar is machined with three right-hand spiral grooves on the outer cylindrical surface of the round drill collar to reduce the contact area with the well wall and effectively prevent differential pressure drilling from sticking.

(3) Non-magnetic drill collars are mainly used for monitoring during oil drilling, and their structures are the same as integral drill collars. Non-magnetic drill collars are made of N1310 low carbon alloy steel, which is forged through strict chemical composition analysis. The material's mechanical properties have been tested to ensure that the hardness, toughness, impact value and corrosion resistance meet standards, and it has good low magnetic permeability and good machining performance.