Gas lift is unusual among lift methods because it has no moving downhole pump. Instead it works on the physics of the fluid column itself: lighter fluid weighs less, so the reservoir needs less pressure to lift it. It is widely used offshore and on wells with high gas content.
By aerating the produced fluid, gas lift reduces the hydrostatic pressure in the tubing — letting the reservoir's own pressure do the lifting. It is especially well-suited to wells with a high gas-oil ratio.
How gas lift works
Compressed gas (usually produced gas recycled through a compressor) is sent down the annulus — the space between the casing and the tubing. At one or more points, gas lift valves mounted on the tubing let the gas enter the production stream. As the gas bubbles into the fluid column, it lowers the average density of the fluid in the tubing.
A lighter fluid column exerts less hydrostatic (back) pressure on the reservoir. With that weight reduced, the reservoir's remaining pressure is enough to push the now-aerated fluid the rest of the way to surface. By adjusting the injection rate, operators tune how much the column is lightened and how much the well produces.
Where gas lift fits
Gas lift shines in several situations:
- High gas-oil-ratio wells — wells already producing lots of gas pair naturally with a method that uses gas.
- Offshore platforms — no large surface stroking equipment is needed, and one compressor can serve many wells.
- Deviated and sandy wells — with no rods or downhole pump to wear out, gas lift tolerates conditions that punish mechanical systems.
The trade-offs are that gas lift requires a reliable supply of compressed gas and surface compression equipment, and it becomes less effective when reservoir pressure is very low, because there must still be enough energy to lift the lightened column. For very depleted, low-pressure wells a pump-based method such as an ESP or rod pump is often better. Compare options in the lift comparison.
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Frequently asked
Gas lift injects gas into the fluid column to lower its density. A lighter column exerts less hydrostatic pressure, so the reservoir's own pressure becomes sufficient to push the aerated fluid to surface — no downhole pump required.
Gas lift suits wells with a high gas-oil ratio, offshore wells where one compressor can serve many wells, and deviated or sandy wells where mechanical pumps wear out. It is less effective on very low-pressure, heavily depleted reservoirs.
Compressed gas is sent down the annulus between casing and tubing and enters the production stream through gas-lift valves mounted on the tubing, mixing into and lightening the fluid column.