TL;DR
Annular preventer seal wear reduces the BOP closing margin. Track the closing pressure trend and test element condition at each BOP pressure test interval.
What you might see
- annular element not closing fully on tubulars
- closing pressure required rising to achieve seal
- visible extrusion of elastomer beyond the packing cavity
- pressure test leaking on the annular function
Likely causes
Elastomer fatigue from repeated close and open cycles over the packing element service life
Temperature excursions from hot well operations degrading elastomer properties
Abrasive wellbore cuttings or scale eroding the element face during stripping operations
Element installed incorrectly with incorrect orientation reducing effective sealing area
Required tools
- Calibrated BOP test unit
- Hydraulic gauges
- BOP test plug
- PPE: H2S escape set, fire-rated coveralls
Safety first
- BOP annular element replacement is a well control operation. Only qualified well control personnel with a written procedure should perform this work.
- The annular preventer is a primary barrier. If it fails the pressure test, the well must be considered underbarriered and the situation managed per the site's well control management plan.
Procedure
- 1
Review the annular closing pressure history over the last 30 to 90 days. A rising trend to achieve the same seal indicates element degradation.[1]
- 2
Perform a low and high pressure test per the regulatory test schedule. A failing test requires immediate element inspection.[1]
- 3
Measure the closing pressure required to seal on the drill pipe or test plug and compare to the value when the element was new.
Warning: Annular preventer inspection and element change requires BOP removal from the wellhead or a qualified field service with written well control procedures. - 4
If the test fails or closing pressure has reached the limit, plan an element replacement.
- 5
Remove the annular preventer top cap and inspect the element for extrusion marks, tears, or cracks.
- 6
Replace the element with a new unit meeting the original specification. Do not substitute a different element durometer without engineering approval.
- 7
After element replacement, re-test to confirm the annular function passes both low and high pressure tests.
Sources
Cameron (SLB) Cameron Type U / TL Blowout Preventer (BOP) general technical documentation, Cameron (SLB)
Cameron Type U / TL BOP general annular preventer testing and element replacement procedures (general)
More guides for Cameron (SLB) Cameron Type U / TL
How to diagnose hydraulic system contamination on a Cameron Type U / TL BOP closing unit
Contaminated BOP hydraulic fluid causes slow function response and valve sticking. Take a fluid sample, change the filters, and flush the circuit before returning the BOP to service.
How to diagnose a ram seal leak on a Cameron Type U / TL blowout preventer
A BOP ram seal leak is a well control equipment integrity failure. Pressure test per the regulatory schedule, identify the leaking seal set, and plan a rebuild.
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