Downhole · ESP
Check & Drain Valves
Two small subs in the tubing above the pump: a check valve that holds the fluid column, and a drain valve above it.
What it does
The check valve keeps the tubing full when the pump stops, so the next start is easier. The drain valve lets the tubing drain before the string is pulled.
Basics
| Check valve depth | About 2 to 3 joints above the pump discharge |
| Gassy wells | A gas cap under the check valve can gas lock the pump |
| Drain valve | Above the check valve |
Common failures
- Check valve leaking, fluid falls back and the pump spins backward
- Drain valve opening by accident
Troubleshooting
- Symptom
- Long time to reach surface after each restart
- Likely cause
- Check valve leaking
- What to check
- Fluid level test after shutdown; plan replacement