The ReedHycalog® V-Stab® tool, NOV Downhole’s revolutionary approach to drill string vibration damping, is an eccentric tool that acts like a lateral shock absorber. By disrupting resonance and damping lateral drillstring vibrations, NOV Downhole has been able to reduce the number of high magnitude shocks that occur during drilling, and reliably minimize damaging vibrations, maximize ROP and increase bit/BHA life.
Effective Vibration Damping
- Variable degree of lateral motion disrupts resonance
- Restricted lateral movement in direction of the blades
- Maximum movement opposite blades
- Some motion between the two at differing rates, disrupts harmonics
- Centripetal force resists off-center rotation
- Damping drill string vibrations
- Proper tool placement is key to success
- Contact your local NOV Downhole representative
Superior Reliability
- One-piece, integral blade design
- No moving/expanding parts minimizing lost in hole cost
- Compatible with fixed cutter and roller cone bits
- Improves performance of hole opening tools
Proven Results
- Dramatically reduces tool and bit damage
- More reliable, longer runs at higher ROP
- Better bit dull condition
- Better hole quality
V-Stab and ‘Friendly Whirl’
After extensive testing by NOV Downhole engineering, a new process has emerged regarding the V-Stab, and how it damps vibration.
It has been concluded that the V-Stab actually promotes ‘Forward Synchronous Whirl’. This ‘friendly whirl’ is a benign vibration mode established in preference to chaotic or backward whirl.
Forward Synchronous Whirl Backward Whirl Chaotic Whirl
- Backward and Chaotic Whirl are very damaging to BHA components with high frequency lateral vibration and reverse bending stresses
- Forward Synchronous Whirl frequency is at drillstring RPM with virtually no reverse bending stresses
Benefits of Forward Synchronous Whirl
- Benign vibration mode established in preference to chaotic or backward whirl
- First mode vibration only – at drillstring RPM
- Relatively low shock levels
- Minimal reverse bending stress – reduced fatigue
- Stick-slip natural damping (brake effect on slip phase/ low friction on stick phase)