Before · Abandonment
Surface Casing Vent Flow
Gas or fluid coming out of the surface casing vent, a sign that something is leaking into the annulus between the surface and production casings.
What it does
If the vent is closed the same leak shows up as annular pressure buildup. In Alberta the vent must be tested before surface abandonment and any flow must be reported and repaired first.
Basics
| Simple test | Hose from the vent under about 2.5 cm of water, watched for bubbles over 10 minutes |
| When | Before surface abandonment |
| Rules | AER Directive 087, section 3.2 |
Common failures
- A poor cement job that leaves a path for gas behind the production casing
Troubleshooting
- Symptom
- Bubbles at the vent during the test
- Likely cause
- Gas source behind casing
- What to check
- Locate the source with logs and repair before cutting and capping