Alert 11 – 22 Failure of BOP Ram Yolk Results in a Natural Gas Release from BOP
A rigless snubbing unit was preparing to stage a production tubing string into a well. The average well bore pressure was recorded at 28mPa (4000 psi). At that pressure it is required to snub the tubing using the ram to ram staging method. As the snubbing operator was staging the coupler of joint #44 into the staging chamber of the snubbing unit, he closed the lower stripping Quick Ram Change (QRC) rams, de-pressurized the chamber, and opened the upper stripping QRC rams. Immediately after the upper QRC rams were opened there was a natural gas release from the closed annular blowout preventer (BOP) on top of the snubbing stack. The operator closed the upper QRC rams and investigated the cause of the release. It was noticed that the lower stripping QRC rams had malfunctioned and did not close properly. The operating yoke of the QRC stripping ram was found to be broken on the left side. This made it impossible to apply the correct closing pressure to the QRC stripping pipe ram to achieve a seal on the tubing. The tubing hanger was staged in using the upper stripping QRC rams and the damaged QRC rams were removed from the snubbing stack and sent for analysis of the failure.
The BOP involved in the incident was within its 3 year required certification, having been inspected 1.5 years ago by a third party recertification facility. No damage or irregularities were detected.