Bits ‘n Pieces – The Driller’s Blog

5 Steps to Preventing Borehole Deviation

Posted by Rod McCoremick on Dec 7, 2015 10:03:00 AM
Rod McCoremick

Even if it is impossible to drill a completely straight hole, sometimes the drill bit starts to bore unpredictably and drillers have to deal with borehole deviation. There are many factors that can influence the direction of a drill hole, and these include the type rock formation in the ground you are drilling, the type of bit used, the weight on the bit, type of rods and equipment, the set-up of the drill rig and its location among others.


Of course, the best way to deal with hole deviation is to take measures to prevent it.

An experienced driller can minimize deviation by using proper drilling tools, making sure they are in good condition and by applying the proper drilling parameters. 

Of course, the best way to deal with borehole deviation is to take measures to prevent it.


Here are 5 steps you can take:

  1. Make sure your drill rig is set up according to the information provided by a geologist. Even a small misalignment at the collar can result in a difference of several meters down below.

  2. Check the weight on bit (WOB) - use a full hole or hexagonal outer tube, combined with front and back reamers, to reduce distortion at the front end of the drill string.

  3. Use a longer reaming shell to ream the hole to the correct constant specific diameter and for even better stabilization.

  4. Consider a larger drill string which will deviate less from planned borehole path.

  5. Geological conditions such as fractured rock can have an impact on the direction of the drill bit. Drilling additives can help you better handle these challenges.


If it is too late and your hole has already deviated from your chosen trajectory, don’t despair, there is equipment out there, like wedges that can help correct the problem.


When facing difficult drilling conditions, do not hesitate to reach out for technical assistance from qualified experts who can help increase your recovery percentage.

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Topics: Tips on common drilling issues

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