Drill string · Drilling
Drill Collars & Stabilizers
Heavy, thick walled steel tubes in the bottomhole assembly, with stabilizers between them.
What it does
The weight of the collars pushes the bit down so it can break the rock. Together with stabilizers and other tools they form the bottomhole assembly, which supplies weight on bit and gives the driller directional control.
Basics
| Collars | Weight on bit |
| Material | Usually carbon steel, sometimes nonmagnetic alloy |
| Part of | Bottomhole assembly (BHA) |
Common failures
- Hole direction drifts off plan
Troubleshooting
- Symptom
- Unplanned change in hole angle
- Likely cause
- BHA behavior not as designed
- What to check
- Review the BHA design and check weight on bit with downhole sensors