Gas Lift Unloading Sequence & Mandrel Spacing Design

About this class

According to many industry experts, Gas Lift is the least understood artificial lift method, but its complexity is not the reason behind its misunderstanding. Instead, the challenge behind Gas Lift is that after implementing a lousy design, the well will often keep producing, unlike other artificial lift methods (e.g., ESP) that stop producing. Thus, operators fail to recognize design or operating errors that restrain production. Therefore, there is a significant potential to increase production by oil and gas professionals who understand the Gas Lift system and its fundamental and advanced principles.

The gas lift training ‘Gas Lift Unloading Sequence and Mandrel Spacing Design’ covers various topics like gas lift initial unloading, routine start-up of a gas lift well, and how to do a mandrel spacing design for optimal performance of the gas lift system.

This gas lift course starts by detailing the gas lift unloading sequence (evolution of tubing and casing pressure profile, CHP, WHP, and valve status during the gas lift well start-up) with IPO and PPO valves.

The course also provides an excellent platform for operators to gain in-depth knowledge of the challenge of integrity in gas lift wells. It will teach the best industry practices and existing solutions to mitigate the specific risks linked to gas lift.

Students will then be guided to make the gas lift mandrel spacing design of a well (number of gas lift mandrels required and at which depth each should be installed) without using any software. Hence, they will understand the fundamental principles of gas lift and know how to select their gas lift well design parameters properly (e.g., kick-off pressure). Advanced notions like the gas lift equilibrium curve, maximum rate estimation, and temperature models are explained clearly to give every student a high level of autonomy when dealing with gas lift design.

The last part of the training explains how to make such a mandrel spacing design using the nodal analysis software Prosper. Students will be guided within the “Gas Lift Design - NEW WELL” form in Prosper (meaning of each parameter to be filled and recommendations on best industry practice). Hence, with our ‘Gas Lift Unloading Sequence and Mandrel Spacing Design’ course, you will better grasp the different options available in Prosper to control your gas lift design.

This lesson is the 3rd of a series of 5 designed to help you reach an advanced level in gas lift oil production and operations. It follows the 2 courses ‘Forms of Gas Lift’ and ‘Gas Lift Equipment’ and precedes the courses ‘Gas Lift Optimization and Design with Existing Mandrels’, and ‘Gas Lift Troubleshooting’.


Participants will acquire a deep understanding of how the gas lift unloading sequence works. They will be able to connect all well parameters during that production phase. This is key knowledge for gas lift optimization and troubleshooting of any well. They will be explained the concept of gas lift mandrel spacing design through an exercise and will be coached so that they can perform such a design themselves manually or by using nodal analysis software to assist them (Prosper). The integrity in gas lift well will also be covered in detail.


  • Unloading the well basic principle
  • Integrity in gas lift well
  • 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
  • Gas lift 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/mandrel spacing design)
  • Unloading sequence videos from suppliers
  • Why installing a gas lift mandrel in a well portion where deviation is higher than 60°
  • Gas lift system (fundamental principles, maximum rate estimation, equilibrium curve)
  • Mandrel spacing design principles (where should you install your gas lift mandrels and how to do such design manually)
  • Temperature models
  • 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 & outlfow)
  • Knowledge of the existing forms of GL and GL equipment (especially GL valves)<
  • Basic knowledge on well architecture
  • Awareness on the oilfield terms.


  • activity icon 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.

  • activity icon Tips for online training
  • activity icon Illustrations to download

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

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

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

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  • activity icon Gas Lift Unloading Sequence by ILS

    This is a nice application to visualize the unloading sequence

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

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