Total SA representatives and Wild Well Control workers boarded the Elgin natural gas and condensate complex in the North Sea on Apr. 6 and confirmed that a planned kill operation to bring the leaking G4 well under control can continue as planned.
After ensuring all necessary safety requirements were met, the team got out of a helicopter and found no gas on the Elgin Process, Utilities, Quarters platform, which is connected by a 90-m bridge to the leaking wellhead platform.
The structural condition of the platform, the G4 wellhead, and the adjacent Rowan Cos. Inc. Viking drilling rig, were found to be unchanged since Total evacuated the complex on Mar. 25. No injuries were reported; 238 people were evacuated (OGJ Online, Mar. 27, 2012).
A visual inspection confirmed the leak is coming from the G4 wellhead at the platform deck level, Total said. In parallel, a remotely operated vehicle confirmed no underwater gas leak.
The team identified piping and hose routing options plus tie-in points for well control equipment. Specialists plan to return to the platform within the coming days to complete the survey and develop detailed plans.
At the same time, preparations are proceeding for the drilling of a relief well and a backup relief well.
Various indications such as regular visual observations from a nearby vessel and temperature measurements seem to suggest that the gas leak rate has decreased during the last few days, Total said.
In comments made late last month, Total said it observed irregular pressure on the plugged G4 well on Elgin field on Feb. 25 so it moved to pump the annulus full of high-density mud.
A sudden pressure increased was noted on Mar. 25, which was followed by an escape of mud and then gas below the wellhead at deck level on the platform.
In the G4 well, the main producing reservoir has been plugged for more than a year. The leaking gas and condensate are believed to be coming from a tight formation at high pressure that is not a producing reservoir in Elgin.
The formation, which is about 1,000 m above the main Elgin producing reservoir, contains a nontoxic gas that could have migrated to the annulus, Total said. No abnormal behavior was observed on the other wells in Elgin field.
Total estimates that shutin production is costing the company about $1.5 million/day of net operation income and that response and remediation activities are costing the company about $1 million/day.
Production was shut in from Elgin and Franklin gas and condensate fields.
Meanwhile, Total already mobilized two rigs to drill the relief well and backup relief well. Both rigs will move to Elgin after final suspension of their current operations. Both rigs already are working for Total.
The Sedco 714 semisubmersible currently is drilling on Fettercairn field north of Elgin. Transocean Ltd. owns and operates Sedco 714. The second rig is a jack up owned by Rowan. The Gorilla V is under contract to drill on West Franklin field.
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