Total UK Ltd. said 5 days of close monitoring confirms the success of a May 15 top kill operation on the leaking G4 natural gas well on the Elgin complex, 240 km from Aberdeen in the UK North Sea.
The West Phoenix semisubmersible pumped heavy mud into the well, and the leak was stopped in 12 hr once the kill operation started, Total UK said. Subsequent inspections confirmed the leak remains completely stopped, Total UK said on May 21.
The G4 well had leaked since Mar. 25, prompting an evacuation of 238 people from Elgin and an adjacent drilling rig, the Rowan Viking. Total UK stopped production on Elgin and Franklin gas fields (OGJ Online, Mar. 27, 2012).
From an estimated initial gas flow rate of around 2 kg/sec, the leak progressively decreased to 0.5 kg/sec until the well intervention, Total UK said.
Now that the kill operation has worked, Total UK said the next step will be for workers to return to Elgin complex and restart the Viking to set cement plugs in the G4 well. The plugging and permanent abandonment phase will take several weeks.
Once the first cement plug is set in the G4 well, the drilling of the ongoing relief well with the Sedco 714 will be stopped. Total UK, in consultation with the appropriate authorities, said experts decided drilling a second relief well by the Rowan Gorilla V is no longer necessary and has therefore been cancelled.