TL;DR
A casing head gasket leak is a surface well control issue. Test the flange, confirm the leak rate, and notify the well control team before any repair.
What you might see
- gas or liquid escaping at the casing head flange
- annular pressure reading below expected
- soap bubble test showing leakage at flange face
- salt deposits or corrosion at flange joint
Likely causes
Gasket relaxation or creep from thermal cycling over the well life
Stud bolt tension loss from corrosion or vibration reducing seating stress
Gasket damage from a previous pressure test or from wellbore chemical exposure
Flange face damage or corrosion preventing adequate seating
Required tools
- Gas detector (H2S and hydrocarbon)
- Calibrated pressure gauge
- Torque wrench (for consultation use only)
- PPE: H2S respirator, face shield, chemical gloves
Safety first
- Wellhead flange leaks are a surface well control incident. Follow your site's well integrity management procedure and notify the well control engineer immediately.
- H2S at the wellhead can reach lethal concentrations within seconds. Always approach a wellhead leak with calibrated H2S monitoring and a supplied-air respirator or escape set.
- Do not attempt self-help repairs on a live wellhead without a written well control plan and competent supervision.
Procedure
- 1
Perform a leak detection check using a gas detector or soapy water at the flange joint. Confirm leak location.
Warning: Wellhead flange leaks involve live wellbore pressure and potentially H2S or hydrocarbon gas. Approach only with appropriate PPE and gas detection. - 2
Measure the annular pressure. Compare to the expected value. A drop confirms loss through the gasket.[1]
- 3
Inspect the visible stud bolt nuts for corrosion or looseness. Do not re-torque stud bolts on a live wellhead without written well control authorization.[1]
- 4
Record the leak rate and location. Submit a well integrity notification to the well control engineer.
- 5
Do not attempt to change a casing head gasket without a full well control plan, bleed-down procedure, and backup well control equipment on site.
- 6
If the leak is minor and stable, monitor the annular pressure and flange area on a defined interval pending the repair plan.
Sources
Cameron (SLB) Cameron Type FC / FLS-R Wellhead / Christmas Tree general technical documentation, Cameron (SLB)
Cameron Type FC / FLS-R wellhead general flange integrity and casing head procedures (general)
More guides for Cameron (SLB) Cameron Type FC / FLS-R
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Actuator failure on a wellhead valve can prevent safe isolation. Check the hydraulic or pneumatic supply, then the solenoid and position feedback before declaring the actuator failed.
How to diagnose a gate valve seat leak on a Cameron Type FC / FLS-R wellhead
A leaking wellhead gate valve seat is a barrier integrity failure. Test the valve per the pressure test procedure and escalate to the well control team if the test fails.
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