“Rocking” Gas-Lift Wells


The operation of ”rocking” a gas-lift well, also called: ”fluid level depressing”, is required to unload the well when the fluid column is heavier than the available lift pressure. Thus, the top gas lift valve cannot be uncovered with the available injection-gas pressure.

”Rocking” the well consists on applying an injection gas pressure simultaneously to the tubing and casing. The injected gas in the tubing will push the fluid column back into the formation; therefore reduce height, thus the weight of the fluids being lifted and allow unloading with the available lift pressure.

The tubing pressure is released rapidly, and the source of the major portion of the fluid entering the tubing is load fluid from the annulus. This procedure may be required several times to lower the fluid level in the casing annulus below the depth of the top gas lift valve.

PS: Several hours may be required to ”rock” a well having low reservoir permeability.

”Rocking” Procedure:

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Gas Lift Instability

By Burney Waring, Consultant at WaringWorld, Inc.

Someone asked me recently about gas lift well instability. This is how I learned to determine if gas lift will be unstable, that is deciding if the well will exhibit casing heading.

As far as I know, this was invented by Dick ter Avest with Shell in 1995, but I think Wim der Kinderen was finally able to explain it to me so I could understand it.

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Guides to Flowing Gradient Survey Data from API RP 11 V5

The purpose of this article is to present rough guides, or “rules of thumb”, to consider when preparing a Flowing Gradient Survey job program for gas lifted well. These recommendations will guide Production Engineers when preparing the survey instruments, planning the survey stop depths and times, when planning to obtain the bottomhole pressure data, as well as when preparing the job program for running pressure & temperature survey.


Preparing the survey instruments:

  • Run sinker bars as needed to overcome pressure surges when entering the wellhead from the lubricator.
  • Sampling rate should be at 30-second intervals.
  • Calibrate the electronic gauge with its software prior to each use.

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Gas lifted well: Operations & unloading process

Gas lift operations and unloading procedure are described in the following demonstration video:

In order to further explain all these aspects and more simplify the process, gas lift operations have been described in the next paragraphs:

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CO2 Tracer Technology for Surveillance of Gas Lifted Wells

CO2 tracer technology is a low cost effective method to quikly and reliably check if a gas lifted well is producing at its optimum conditions.

Actually, the CO2 tracer survey would detect the operating lift depth, multiple points of injection, tubing leaks.

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