Alert 10 – 34 Fatality Occurs During Offline Cementing Operations
The operation at the time of the incident was rigging down the cementing head and bonnet. It is believed that the crew started rigging down the ancillary parts of the cement head (hoses and a “T” piece) some hours before the final rig down job commenced. As part of this preparatory work the lower valve on the cement head was closed to prevent fluid leaking onto the deck after the return line was drained. This valve remained closed until the time of the incident. During the time between the closure of the valve and the removal of the cement bonnet, pressure continued to build up in the system due to the effects of thermal expansion from the cement job. The calculated pressure build up within the system was more than 140 psi. Later the Well Head Engineer (WHE) went to the dog house with the JSA (Job Safety Analysis) for the ‘Installation of the Xmas Tree’ (which followed the rigging down of cement head activity). The WHE discussed the JSA with the Tourpusher, who told the WHE to wait until the cementing supervisor arrived, so that all parties were present and the JSA could be conducted for all elements of the task, beginning with rigging the down of the cement head.
While waiting for the cementing supervisor, the WHE met with the Assistant Driller (AD), who was the supervisor responsible for assisting both Service Companies with the manpower and lifting capabilities for rigging down the cement head / bonnet and installation of Xmas tree. They went through the WHE’s JSA and then proceeded to the production deck and the well head in question. Prior to the arrival of the cementing supervisor and prior to conducting the pre-job meeting, the locking nuts from the cement bonnet were all released. There was no check and the personnel did not recognize that it was under pressure. As the last locking nut was loosened, the bonnet and cement head released from the well (pushed upwards) and toppled towards the AD, pinning him between the annulus valve on an adjacent well and the cement head. The AD was severely injured and passed away shortly after.