Artificial Lift Consultant and Well Performance Specialist

The LGLC Gas Lift Blog

The LGLC Gas Lift Blog provides a space to learn more about trending gas lift topics.

GAPL is not Intermittent Gas Lift

GAPL is not Intermittent Gas Lift
 
Gas Assisted Plunger Lift (GAPL) is a totally different lift technique to Intermittent Gas Lift (IGL). GAPL uses a screen orifice and a plunger on bottom and the opening and closing of a surface controller attached to the flowline at surface to lift the plunger.
 
IGL uses an injection pressure operated gas lift valve on bottom which opens at high pressure to ballistically lift accumulated fluid above it. For deep IGL installations a plunger may be used above the bottommost gas lift valve to reduce liquid fallback, and the installation becomes known as Plunger Assisted Gas Lift (PAGL). PAGL, when applicable, further reduces the injection gas requirement of an IGL installation by 30 to 70%.
 
IGL installations cost efficiently gas lift fluid to less than 10 barrels of fluid per day (bfpd), with gas injection rates less than 100 mcfd. The attached 2 Pen Pressure Recording Chart shows efficient IGL operation.
 
One major operator in the Permian Basin successfully converted rod pumped wells averaging 24 bfpd in an old waterflood unit to IGL installations. At industry normal of 0.5 Failure/Well/Year on rod pump, this equates to savings of $50K to $100K per well using IGL.
 
In another case, a 14,760 feet deep SCOOP/STACK well in Oklahoma was converted from GAPL to IGL. The result was a 39 bopd increase and a gas injection rate decrease from 650 to 260 mcfd.
 
There are two methods used to control gas injection at surface into the casing of IGL installations: Injection Gas Choke Control, and Time Cycle Intermittent Control. Surface installation costs to convert a continuous gas lift well to IGL using these installations are $5,500 and $18,000 respectively. In each of these IGL installations there is no motor valve/controller attached to the flowline, unlike GAPL. IGL also has fewer moving parts to fail compared to GAPL. Plungers used in GAPL are also subject to reservoir surges and easily damaged from consequent dry runs.
 
Intermittent Gas Lift is quickly becoming the technique of choice when savvy operators transition from high volume continuous gas lift to intermittent lift for wells producing less than 300 barrels of fluid per day.