A Darcy Member asked for any information on Gas Assisted Plunger Lift (GAPL/PAGL) specifically related to how much of a reduction in gas lift volumes would be typically experienced when undergoing GAPL, the mechanism behind this, and the factors that influence its effectiveness.

Below is a summary of the information gathered. Special thanks goes to Tally Energy Production Services and the EPIC team for their valuable input.

What can be achieved with GAPL/PAGL with respect to:

Over/under Injection

• One of the biggest issues seen in GAPL is over-injection. When a plunger is introduced to a gas lift system, we increase the efficiency of that gas lift system by significantly decreasing the amount of liquid fallback during the cycles. The plunger is depending on the injection from the gas lift to the surface while also “wiping” the whole tubing string clear of fluids. This allows more formation gas to enter the tubing. When this happens, you will not need as much injection gas to surface the plunger. By lowering the injection gas, you can lower the flowing bottom hole pressure and decrease the resistance to the formation. This generally results in a fluid and gas increase. It is hard to put a number to this as the permeability and output of formations vary so much.
• Many times, compressors are not sized appropriately for the injection rates required. In this circumstance, you can not achieve the injection rates needed to keep the well above critical velocity. By introducing GAPL we can make more efficient use of the gas available to unload fluid. When this happens, we generally see more formation gas and can achieve the required critical velocities to unload efficiently.
• Some operators have been able to reduce gas volumes by 80% allowing for the removal of 2-4 compressors on site which is a huge savings on LOE.

Paraffin control

• Many times, GAPL is utilized simply to control the formation of paraffin in the upper wellbore. By introducing a plunger running multiple times per day, we are able to use the plunger as a scraper just as you would on slickline. This action as well as the increased velocities of the fluid past the cold zone in the wellbore inhibit the formation of paraffin plugs in the wellbore.
• If paraffin is found in conjunction with other inefficiencies, you will often see a production increase as well.

Lowering injection depths

• If parameters have changed from the time of design to current production and the gas lift system is not operating from its intended injection depth GAPL can help.
• Once again by introducing the plunger to the system, we can increase the efficiency of the gas lift system. When we do this, we can lower bottom hole pressures and allow the system to “valve down”. This in turn will continue to lower the bottom hole pressure and allow for an increase in production. The plunger lift system can then be transitioned further downhole and continue to increase efficiencies.

Let us know your thoughts/comments about your experience with GAPL/PAGL in the comments below. If you would like to view Darcy's content in the space, below are a few links to content in this space.

Artificial Lift with Flowco Production Solutions: here the Flowco team held a discussion about the life of a well on Gas Lift with an emphasis on GAPL/PAGL applications and case studies.

Civitas' 15% Production Increase w/ Tasq; XTO & Ensign on PL Optimization: this forum focused on Plunger Lift innovation and featured a software provider with their user, along with two other operators in the space. Also, XTO and Ensign share learnings in the space.