Gas Lift unloading sequence and mandrel spacing design

In Oil Production

About this class

According to many industry experts
Gas Lift (GL) is the least understood artificial lift method, but the reason
behind that is not its complexity. While when you do things wrong on other
artificial lift methods (e.g. ESP) your well will stop producing, a GL well
will often keep on producing even with a bad design. Hence many operators often
do not realize that their GL well is not producing at its full potential and
don’t pay attention to it.

There is therefore a very significant potential for production increase by
understanding the principles of GL and this is a huge opportunity for any
engineer willing to master this activation method.

This class is the 3rd of
the series of courses related to gas lift activation. It follows the courses
“Forms of GL”  and “GL equipment”. It details
the GL unloading sequence (evolution of tubing and casing pressure profile,
CHP, WHP and valves status during the GL well start up) with IPO and PPO valves.
Student will be guided to make the mandrel spacing design of a well (selection
of gas lift mandrels depth) so that they can understand the principles behind
that choice and how to select their parameters properly (e.g. kick off
pressure). The last part of the training explains how to make such a mandrel
spacing design using the software Prosper. Student will be guided within the
“GL design new” form in Prosper (meaning of each parameter to be filled and
recommendation on best option to select).


Participants will acquire a deep understanding
on how the GL unloading sequence works. They will be able to connect all well
parameters during that production phase. This is a key knowledge to be able to
troubleshoot any GL well. They will be explained the concept of a mandrel spacing
design through an exercise and will be coached so that they can perform such a
design themselves using a software to assist them (Prosper).



  • Unloading the well basic principle
  • Initial unloading following a drilling or a WO (how to
    empty your casing of the mud/brine without damaging your valves)
  • Unloading sequence with IPO valves
  • Unloading sequence with PPO valves
  • GL unloading principle explained by counting bubbles
    of gas
  • Gas gradient formula and rule of thumb to quickly
    calculate your casing pressure at any depth
  • Put it all together with an exercise
    (inflow/outflow/SPM design)
  • Unloading sequence videos from suppliers
  • Why installing a GL mandrel in a well portion where
    deviation is higher than 60°
  • Mandrel spacing design principles (where should you
    install your gas lift mandrels)
  • How to choose your kick of pressure
  • Guidelines to make a mandrel spacing design with
    Prosper (how to fill the “GL design new” form in Prosper).

This course is designed for:

  • Production, Petroleum or Well Performance Engineers to
    understand how the GL unloading sequence works and how to make a mandrel
    spacing design
  • Field Production Personnel to understand how their GL well
    work and respond better to the questions of their support teams in town
  • Completion Engineers to understand fully the needs for
    mandrels in a GL well.


  • Understanding of the well production mechanisms (inflow &

  • Knowledge of the existing forms of GL and GL equipment (especially
    GL valves)

  • Basic knowledge on well architecture

  • Awareness on the oilfield terms.


  • Announcements

    Welcome!  This training course is the culmination of researching papers, manuals, and lessons learned from my years of experience in the field.  I have carefully selected the best material to help you grasp concepts quickly and retain them for years to come.

    Our courses go through a continuous improvement process, which is critical for ensuring industry best practices and topics remain relevant with technological advancements.  Your feedback also plays a vital role in the process.  Thus, we welcome your thoughts on the course and encourage your input for future improvement of this training course.

    Thank you for purchasing this course.

  • Tips for online training
  • Illustrations to download

    Print these slides and use them to take notes along the videos.

  • 01-Unloading the well
  • 02-Initial unloading following a drilling or Workover
  • 03-Unloading sequence with IPO valves
  • 04-Unloading sequence with PPO valves
  • 05-Counting bubbles (fiction cases)
  • 06-Gas gradient
  • 07-Exercise hypothesis

    Last hypothesis not mentioned in the video:
    We will assume a gas gradient of 0.8 bar per 100 m in the casing.
    It is the value that I used to build the graphics on the slides. It helps to simplify the exercise, while keeping the essence of it.

    In the quiz, I will also ask you to calculate casing pressure values at depth, with a more precise gradient value, using the rule of thumb presented in the training.

  • 08-Exercise questions
  • Quiz 1
  • 09-Exercise answers - Inflow
  • Quiz 2
  • 10-Exercise answers - Outflow 1
  • Quiz 3
  • 11-Exercise answers - Outflow 2
  • Quiz 4
  • 12-Exercise answers - Outflow 3
  • Quiz 5
  • 13-Exercise answers - Mandrel spacing design
  • 14-Unloading sequence videos from Gas Lift suppliers
  • GL simulator by Dover Artificial Lift
  • GL unloading sequence
  • Quiz 6
  • 15-How to choose extra Gas Lift Mandrel depth
  • 16-Why installing a Gas Lift Mandrel if well deviation is higher than 60°
  • 17-Mandrel spacing design principles
  • 18-How to choose the Kick Off Pressure
  • 19-Guidelines for SPM design with Prosper-1
  • 20-Guidelines for SPM design with Prosper-2
  • 21-Guidelines for SPM design with Prosper-3
  • Quiz 7
  • Conclusion

    Congratulations, you have reached the end of the training. 

    We hope you enjoyed the learning experience. Please don't hesitate to send us your comments and feedback to help us improve the experience.  

    Thank you for purchasing this course, and don't forget to check out our other training content.

  • Natural gas compressibility factor calculator
  • Gas Lift Unloading Sequence by ILS

    This is a nice application to visualize the unloading sequence

  • Simple Mandrel Spacing by Burney Waring
  • Simple mandrel spacing application by Burney Waring
  • Gas Lift mandrel spacing alternative method for unconventional wells

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