Stuck Pipe Prevention

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Stuck Pipe Prevention Self-Learning Course
SUGAR LAND
LEARNING CENTER
Stuck Pipe Prevention
SELF - LEARNING COURSE
USEFUL PRE-REQUISITES
“A Primer of Oilwell Drilling”
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Stuck Pipe Prevention Self-Learning Course
Introduction to self-learning:
Self-learning enables you to learn at your pace, in your time and in your way. This course
book provides the content, structure and organization of your learning which would
otherwise be managed by an instructor in a class. It also asks you questions to help you to
confirm your understanding (as the instructor probably would). You will also find a recap
section that will be useful for you to review the important points stressed in this book
after your training. At the end is a glossary containing the key-words relating to the
subject, and the answers to the questions.
Structure:
Each section contains:

Explanation of the subject, illustrated as much as possible.

Questions (the answers are in Appendix B).
How to use the course book:
• Try to do the course in a maximum of 2 hours, with a break.
• Set yourself in a suitable environment (no noise, no interruptions, etc...).
• After reading a section, use the self-test questions to confirm what you have
understood. Write down the answers on a sheet of paper and check the answers at the
end of the book. It is your responsibility to answer honestly. If you get an answer
wrong, go back to the section indicated and review the subject.
• A few days later, or at any moment, use the recap section and the glossary to refresh
your knowledge of the subject.
Remember:
Learning is your responsibility. This book provides you with a good preparation before
the seminar to the Sugar Land Learning Center and gives you a chance to learn more by
not struggling with the basics.
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Table of Contents
Introduction......................................................................................................................... 5
1. What is a “Stuck Pipe” ?................................................................................................. 7
2. Mechanisms ................................................................................................................... 9
2.1 Differential Sticking................................................................................................ 11
2.2 Inadequate Hole Cleaning ....................................................................................... 16
2.3 Chemically Active Formations ............................................................................... 18
2.4 Mechanical Stability .............................................................................................. 20
2.5 Fractured/Faulted Formation.................................................................................. 22
2.6 Overpressured Formations ..................................................................................... 24
2.7 High Dip Sloughing ............................................................................................... 26
2.8 Unconsolidated Formations ................................................................................... 28
2.9 Mobile Formations................................................................................................. 30
2.10 Undergauge Hole ................................................................................................. 32
2.11 Key Seating .......................................................................................................... 34
2.12 Wellbore Geometry............................................................................................... 36
2.13 Junk....................................................................................................................... 38
2.14 Collapsed Casing .................................................................................................. 39
2.15 Cement related ...................................................................................................... 40
2.15.1 Cement Blocks ............................................................................................... 40
2.15.2 Green Cement ................................................................................................ 41
Questions: Mechanisms ................................................................................................ 43
3. Prevention .................................................................................................................... 45
3.1 Planning ................................................................................................................. 47
3.2 Monitoring at the Well site .................................................................................... 48
Questions: Prevention ................................................................................................... 52
4. Recap section ............................................................................................................... 53
4.1 Summary ................................................................................................................ 55
Appendix A : Glossary..................................................................................................... 61
Appendix B : Answers to Questions................................................................................ 63
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Introduction
Welcome to the Stuck Pipe Prevention self learning course. Stuck pipe is one of the most
important problems you will find in the oil-industry. This book will introduce you to
stuck pipe, explain the different mechanisms and how to prevent stuck pipe. After
completion of this self-learning course, you will find more information in the IWOB self-
learning package, relating to SPIN. Also refer to the Sedco Forex “ Driller’s Stuck Pipe
Handbook”.
T
S
T
B
T1 and T2, tension : the drill pipe is always in tension when drilling.
S, side force :
when 2 surfaces are in contact with a perpendicular side force
acting between them, any attempt to move one surface relative to
the other will result in a friction force resisting the motion.
B, buoyant weight :
apparent weight of the element in the mud.
Figure 1
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1. What is a “Stuck Pipe” ?
Drilling a well requires a drill string (pipe & collars) to transmit the torque provided at
the surface to rotate the bit, and to transmit the weight necessary to drill the formation.
The driller and the directional driller steer the well by adjusting the torque, pulling and
rotating the drill string.
When the drill string is no longer free to move up, down, or rotate as the driller wants it
to, the drill pipe is stuck. Sticking can occur while drilling, making a connection, logging,
testing, or during any kind of operation which involves leaving the equipment in the hole.
We can define:
MO, maximum overpull : the max. force that the derrick, hoisting system, or drill pipe
can stand, choosing the smallest one.
BF, background friction : the amount of friction force created by the side force in the
well.
FBHA :
The force exerted by the sticking mechanism on the BHA
(Bottom Hole Assembly)
The drill string is stuck if BF + FBHA > MO
In other words, the drill string is stuck when the static force necessary to make it move
exceeds the capabilities of the rig or the tensile strength of the drill pipe. Stuck pipe can
result in breaking a part of the drill string in the hole, thus losing tools in the hole.
A few variables must be taken into account when dealing with stuck pipe: pore pressure
of the formation, mud system, and the depth versus time (the longer in the hole without
action, the more likely to get stuck).
The consequences of a stuck pipe are very costly. They include:
• Lost drilling time when freeing the pipe.
• Time and cost of fishing: trying to pull out of the hole the broken part of the BHA.
• Abandon the tool in the hole because it is very difficult or too expensive to remove it.
In that case the oil company pays Anadrill to replace the tool.
To give you an idea, an average cost per well of sticking pipe is about $50 000 US. Our
service is to avoid the costly loss of the BHA (bottom hole assembly) to the client. Our
responsibility is to protect the Anadrill tools contained in the BHA.
Question 1 : What is a stuck pipe ?
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2. Mechanisms
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