Category Archives: Oil Field Knowledge

Drilling Jar and Accelerator (Fishing Tools) Video

By | | , ,
3 Comments

A drilling jar is used to increase pulling capacity to free the stuck pipe and an accelerator is used to intensify force generated by the drilling jar at the upper depth of the well.

This video demonstrates how a drilling jar and an accelerator are activated to free the stuck pipe.

Summary from this video

• The more you pull on the drilling jar before it is tripped, the more power you will get from the drilling jar.
• Drill collars placed above the drilling jar enhance the performance of the hydraulic jar.
• The jar accelerator is used to intensify effect of jar at any depth. Use of the accelerator is very effective in a shallow fishing operation.
• The accelerator helps keep the energy generated by jar impact from being lost up hole.
If you cannot see the video for some reasons, please check out this link http://youtu.be/w-9gd2eeibc.

I wish you would enjoy learning about the drilling jar and the accelerator.

How To Free Stuck Pipe Caused By Wellbore Geometry

By | | ,
Leave a comment

If you already know that the stuck pipe is caused by wellbore geometry, these following instructions are guide lines on how to free the stuck drill string.

What should you  do to free the stuck pipe caused by wellbore geometry?

  • If the drill string gets stuck while moving up, jar down with maximum trip load and torque can be applied into the drill string while jarring down. Be cautious while applying torque, do not exceed make up torque.
  • On the other hand, if the drill string gets stuck while moving down, jar up with maximum trip load.DO NOT apply torque in the drill string while jarring up.
  • Flow rate must be reduced while attempting to free the drill string.Do not use a high flow rate because it will make the stuck situation become worse and you will not be able to free the pipe ever.
  • To free the string, a jarring operation may take a long time, so please be patient.
  • If a formation that gets stuck is limestone or chalk, acid can be spotted to dissolve cuttings around the pipe.
  • If the drill string is stuck in a salt formation, spotting fresh water is another choice to clear the salt in the annulus.
  • Please always seriously consider the situation regarding well control prior to spotting lightweight stuff (acid or fresh water) around the drill string. You must ensure that you are still over balance formation pressure otherwise you will be dealing with well control too.

What should you do after the string becomes free?

  • Increase flow rate and circulate to clean wellbore. Flow rate must be more than the cutting slip velocity in order to transport cuttings effectively.
  • Reciprocate and work pipe while cleaning the hole.
  • Ensure that the wellbore is clean prior to continuing the operation.
  • Back ream or make a short trip to the section that caused the problem.

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.

 

Washover Operation with Washover Pipe

By | | ,
Leave a comment

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

By | | ,
1 Comment

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.