The drill collar is located at the bottom of the drill string and is the main component of the lower drilling tool assembly. Its main characteristics are a large wall thickness (usually 38-53mm, equivalent to 4-6 times the thickness of the drill pipe wall), with significant gravity and stiffness. For the convenience of drilling and tripping operations, it is possible to machine elevator slots and slip slots on the outer surface of the internal threads of the drill collar.
Chinese name drill collar
Foreign name drill collar
Function to make the drill bit work smoothly, etc
Material AISI4145H chromium molybdenum alloy steel
Device drill string
Types: Spiral drill collar, non-magnetic drill collar, integral drill collar
catalogue
Introduction to Drill Collar 1
2 Functions
3 specifications and dimensions
Introduction to Drill Collar
Made of AISI4145H chromium molybdenum alloy steel through rolling or forging, effectively controlling the chemical composition and trace element content.
(1) Apply drilling pressure to the drill bit;
(2) Ensure the necessary strength under compression conditions;
(3) Reduce the vibration, oscillation, and jumping of the drill bit to ensure smooth operation;
(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 overall drill collar is a smooth thick walled circular pipe with threaded connections at both ends.
(2) The spiral drill collar is machined with three right-handed spiral grooves on the outer cylindrical surface of the circular drill collar to reduce the contact area with the wellbore wall and effectively prevent pressure differential from jamming the drill
(3) Non magnetic drill collars are mainly used for monitoring during oil drilling processes, and have the same structure as integral drill collars. The non-magnetic drill collar is made of N1310 low-carbon alloy steel, which is forged through rigorous chemical composition analysis. The material has undergone mechanical performance testing to ensure that its hardness, toughness, impact value, and corrosion resistance meet the standards, and it has good low magnetic permeability and good mechanical processing performance.
For the convenience of drilling and tripping operations, it is possible to machine elevator slots and slip slots on the outer surface of the internal threads of the drill collar.
Grace Ma
Email: oiltools14@welongpost.com
Post time: Jun-27-2025
