Liquid Loading: The Well That Drowns Slowly
As gas wells age, bottomhole pressure falls and the gas can no longer carry produced water and condensate to the surface. Liquid accumulates in the tubing downhole. That condition is called liquid loading. The liquid column adds hydrostatic head that works against the reservoir's natural pressure. Flow becomes intermittent, production drops, and if the loading is never addressed the well can stop producing altogether.
How It Works: The Well Lifts Its Own Load
Plunger lift uses a steel plunger that rides inside the tubing. The plunger carries a bypass valve and lands on a bumper spring near the bottom of the well. Each cycle starts with the surface valve closed. The well is shut in, and gas pressure builds in the annulus between casing and tubing. At a preset pressure the controller opens the valve. Gas from the annulus rushes in below the plunger and pushes it, with the liquid slug on top, to the surface. A lubricator at the wellhead catches the plunger while the liquid flows into the sales line. When the well unloads, the valve closes and the plunger falls back for the next cycle. No outside energy source is needed. The well lifts its own load.
Control and Fit: Choosing the Right Well
Controllers range from simple timers to smart automation. Smart controllers watch casing, tubing and line pressure, track plunger arrival times, and tune each cycle as the well changes. That matters in the field. Launch too early with little liquid load and the plunger travels too fast and can damage the wellhead catcher. Launch too late with too heavy a load and the plunger stalls. Both errors waste gas and often end in venting. Compare that with a blowdown: venting clears the liquid but dumps methane and must be repeated as liquid builds back. Plunger lift keeps the methane in the line. EPA and SLB guidance point to the same candidates: wells with shut-in pressure roughly 1.5 times the line pressure, and wells that make at least 400 standard cubic feet of gas per barrel of liquid per 1,000 feet of depth.
Plunger lift works best when the whole well is watched, not just the controller. Keep surface hardware in shape with beam pump unit maintenance, keep paraffin off the tubing with paraffin control and treatment, and watch the field from the office with remote well monitoring and SCADA. Then close the loop with an operations audit so the data sets the cycle, not a timer nobody has touched in months.