Downhole · Plunger Lift
Plunger
A free traveling piston with a bypass valve that runs up and down the tubing.
What it does
Falls with its bypass valve open, closes when it lands at bottom, then rides up on the annulus gas carrying the liquid above it. It also scrapes early paraffin and scale off the tubing wall.
Basics
| Seal | Small clearance with the tubing wall |
| Bypass valve | Open going down, closed going up |
| Side benefit | Scrapes paraffin and scale |
Common failures
- Wear that opens the clearance and lets liquid slip past
- Erosion or sticking in sandy wells
- Bypass valve that does not close at bottom
Troubleshooting
- Symptom
- Slow rise and little liquid at surface
- Likely cause
- Worn plunger, poor seal
- What to check
- Inspect the plunger every 1 to 3 months and replace it when worn
- Symptom
- Plunger does not come up after the valve opens
- Likely cause
- Bypass not closing at bottom or plunger stuck
- What to check
- Check the arrival history; retrieve and inspect