Downhole · Plunger Lift
Liquid Slug
The column of water, oil or condensate that collects above the plunger and is lifted to surface each cycle.
What it does
Removing it stops liquid loading: without lift, its hydrostatic weight works against reservoir pressure until gas flow slows and stops.
Basics
| Best fit | Liquid below about 130 bbl/d (21 m3/d) |
| Gas needed | At least 400 ft3 of gas per bbl of liquid per 1,000 ft of depth |
| Pressure rule | Shut in wellhead pressure about 1.5 times line pressure |
Common failures
- Slug too heavy for the pressure available, the plunger stalls
Troubleshooting
- Symptom
- Gas rate keeps falling between cycles
- Likely cause
- Liquid load building faster than the cycles remove it
- What to check
- Adjust the flow period after plunger arrival, which controls the liquid load