Micro dogleg occurs in areas where there are several corrections in inclination and azimuth and it most likely happens in hard/soft interbedded rock. If there are micro dogleg areas in the well, the bottom hole assembly can get stuck.
Warning signs when you get stuck due to Micro Dogleg
- Hard and soft streak formations are drilled. You can easily observe from the changes in ROP.
- Inclination and azimuth are frequently changed.
- Drilling the well with a mud motor causes this issue because of rotating and sliding operations.
Stuck identification for Micro Dogleg
- Drilling torque and drag are erratic.
- It can happen while tripping or drilling.
- Circulation can be established without any restriction.
What should you do for this situation?
- If the drill string is stuck while moving up, jar down with maximum trip load. Torque can be applied with caution while jarring down.
- If the drill string is stuck while moving down, jar up with maximum trip load without applying any torque in drill string.
- If the drill string is free, you may need to consider back reaming to clear micro dogleg.
- Minimize changes in inclination and azimuth
- Back ream operation should be performed when hard/soft streak is drilled.
- Slow down tripping sleep when entering possible problematic zones.
John Mitchell Drilbert Engineering, 2002. Trouble-Free Drilling Volume 1: Stuck Pipe Prevention. Edition. Drilbert Engineering Inc.
Fanarco.net. 1999. Stuck Pipe Prevention Self-Learning Course. [ONLINE] Available at: http://www.fanarco.net/books/drilling/stuck-pipe.pdf. [Accessed 21 June 2016
Steve Devereux, 2012. Drilling Technology in Nontechnical Language, 2d Ed.. 2 Edition. PennWell Corp.