Undergauge Hole Causes Stuck Pipe

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Undergauge hole can  happen when drilling in hard and abrasive formations where it wears down a drill bit. When the bit is undergauge because the abrasive formation wears a bit and stabilizes, a hole size becomes smaller. When the new BHA is run in hole, the new bit/BHA gets stuck into the undergauge hole section. Additionally, if coring is performed with a smaller core bit than the next bit, the new bit can get stuck at the top of the coring section.

Undergauge hole is caused by abrasive formations

Undergauge hole is caused by abrasive formations

The drill string gets stuck at the undergauge section

The drill string gets stuck at the undergauge section.

Warning signs when you get stuck due to Undergauge Hole

  • Drilling into abrasive formations.
  • A bit and stabilizers are undergauge.

Stuck identification for Undergauge Hole

  • This type of stuck pipe occurs only when tripping in hole.
  • Sit down weight suddenly increases.
  • The bit gets jammed off bottom.
  • Circulation can be established.

What should you do for this situation?

  1. This stuck pipe always happening while the drill string is being moved down, therefore you need to jar up with maximum trip load without applying any torque in the drill string.

Preventive actions:

  1. Properly gauge bit/stabilizer after it is pulled out so you will know the possibility right away.
  2. Do not stage weight in order to pass the tight spots. The more weight you put on top, the harder to free the pipe.
  3. If the undergauge bit/stabilizer is observed, you need to ream down at least 1-2 stands off the bottom.
  4. Reaming at least 1-2 stands above the top of the coring section.
  5. Trip in hole with controlled speed prior to going to possible problematic areas.

References

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.

 

Diesel Engine and Electric Power (Rotary Drilling) Book Review

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This is one of books in the rotary drilling series from Petroleum extension service, University of Texas at Austin. It contains a lot of basic knowledge regarding diesel and electric power for drilling rig. As you may know, it is not easy to understand all about basic details about engines used in the drilling rigs because there are so many details.

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Washover Operation with Washover Pipe

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This is a short VDO demonstrating wash over operation with washing tool.

If you cannot see it, please find it via youtube here http://youtu.be/2kIQFuyj_bQ

When the wellbore is collapsed and there are formations over the fish, you need to wash over the top of fish in order to clear any sands or debris.

 3-Wash-Over-Operation-fb2

(Washover Pipe)

The washover pipe is used for this operation. It will slip over the stuck pipe and drilling mud will flush out any debris in the annulus between pipe and wellbore. When the top of fish is clean, you can run in hole with fishing assembly to engage and recover the fish down hole.

Note: This VDO is a part of Weatherford Fishing Service.

 

Mobile Formation Causes Stuck Pipe

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Mobile formation is caused by overburdened pressure that squeezes shale and/or salt into a wellbore. The squeezed formations reduce wellbore diameter; therefore, the drill string/BHA gets stuck due to under gauge wellbore.

Mobile Formation Causes Stuck Pipe

Mobile Formation Causes Stuck Pipe

Warning signs when you get stuck due to mobile formation

  • Salt and shale are drilled. You can see from the Mud logging samples showing shale. Moreover, Chloride content must be increased in case of drilling into salt zones.

Stuck identification for mobile formation

  • Over pull, down weight and torque are suddenly increased.
  • It could happen at anytime as drilling, tripping in and tripping out depending on how fast plastic formations are moved.
  • Most of the time, the BHA gets stuck at the plastic zones because BHA contains the largest diameter component.
  • Circulation is not restricted or is just slightly restricted.

What should you do for this situation?

  1. If the drill string is stuck while moving up, jar down with maximum trip load. Torque can be applied with caution while jarring down.
  2. If the drill string is stuck while moving down, jar up with maximum trip load without applying any torque in drill string.
  3. If you are sure that the plastic formations drilled are salt, you may consider spotting fresh water to dissolve the salt. However, you need to consider regarding well control issues.

Preventive actions:

  1. Use sufficient mud weight to hold back formation movement.
  2. Back ream and wiper trip should be performed across the suspected rocks.
  3. Minimize time for open hole exposure.
  4. Trip in hole with caution prior to entering possible problematic formations.

References

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.

Micro Dogleg Causes Stuck Pipe

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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.

Micro Dogleg Causes Stuck Pipe

Micro Dogleg Causes Stuck Pipe

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?

  1. If the drill string is stuck while moving up, jar down with maximum trip load. Torque can be applied with caution while jarring down.
  2. If the drill string is stuck while moving down, jar up with maximum trip load without applying any torque in drill string.
  3. If the drill string is free, you may need to consider back reaming to clear micro dogleg.

Preventive actions:

  1. Minimize changes in inclination and azimuth
  2. Back ream operation should be performed when hard/soft streak is drilled.
  3. Slow down tripping sleep when entering possible problematic zones.

References

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.