Destructive Drilling Dynamics
In drilling, there are three main types of vibration: Axial – along the axis of the drill string; Lateral – in a side to side motion, perpendicular to the drill string; and Torsional – the wrapping and releasing of the drill string.
Modes of vibration:
- Stick-Slip: Torsional mode vibration; bit rotation speed cycles or negative from zero to several times average
- Bit Bounce: Axial mode vibration; bit pounds bottom of hole
- Forward or Backward BHA Whirl: Lateral mode vibration; drillstring rolls around or bangs against side of hole
- Bit Whirl: Lateral mode vibration; bit rotates unevenly
Vibration modes can couple and excite other modes of vibration.
What are the sources of vibration?
For a drill string, there are numerous excitation sources that can impart energy into or excite the drill string: cutting action of the bit, drill string rotation and stabilizer contact with the borehole wall to name a few. All drill strings will vibrate. If these vibrations become severe drilling efficiency is reduced and damaging drilling dysfunction will be induced.
Severe vibration can result in damage and failure that results in incremental equipment costs and is detrimental to drilling performance.
Challenges encountered by excessive lateral, axial, or torsional vibration:
- BHA Failures – mechanical and electrical
- Reduced bit life and severe bit damage
- NPT due to tripping for failures – more time for wellbore exposure issues
- Extremely low drilling rates
- Severe wear on BHA components or drill string
- Poor weight transfer
- Casing wear
- Twist off
- Wellbore stability issues
- Poor wellbore quality leading to excessive torque and drag
- Inability to drill to TD
Rubicon offers a wide range of technologies and expertise to help minimize problems related to both lateral and axial vibration. Enabled through our advanced Applications Engineering teams and industry leading software, we provide our customers with a better understanding of the wellbore environment. Our technology portfolio combined with our team of experienced professionals help reduce risk, mitigate unplanned costs and improve overall performance.