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6-Gas Lift unloading sequence and mandrel spacing design


Product description

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
  • 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.


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