North Sea Gas Leak
On 25 March, as we were preparing this issue to go to press, Total reported a gas leak at the Elgin gas field located in the UK North Sea approximately 240 kilometres east of Aberdeen.
Elgin, along with the Franklin field, lies in the Central Graben Area of North Sea, and Total E&P UK Limited owns 46.17% and is operator of both fields through its wholly-owned subsidiary Elf Oil and Gas Limited and its average share of production was around 60,000 barrels of oil equivalent per day in 2011. Together, the Elgin and Franklin fields represent about 9% of UK gas production.
Elgin and Franklin fields each have a wellhead platform (WHP), and they share a Production-Utilities-Quarters (PUQ) platform, which collects, separates and treats produced hydrocarbons. The fields are high-pressure/high-temperature gas and condensate fields, and Elgin’s reserves are deep, at 5,500 metres below the seabed, with temperatures around 200° C and pressures of 1,100 bar.
The gas leak occurred during operations to plug and decommission well 22/30c-G4, and although the exact cause is not yet known, the difficulties posed by the field’s high pressures and temperatures, along with the other geological conditions, are thought to be the root cause of the leak.
The Elgin G4 wellhead assembly with a clear view of the source of the gas leak coming out of four ports (release points) – localised deposits of condensate and drilling mud were expelled on the wellhead area of the Elgin Well Head Platform at the beginning of the leak and have solidified (photo: Total E&P UK Ltd)
On 25 March, Total immediately launched internal emergency procedures and Crisis Management Teams were mobilised in Aberdeen and Paris. Fortunately, no injuries or fatalities were reported. All 238 personnel were accounted for, and 150 non-essential personnel were flown to Aberdeen as a precautionary measure. An additional 69 non-essential crew remained offshore on neighbouring installations.
Two days later, on March 27, Total reported that a surveillance aircraft had been flown over the area, which confirmed a sheen on the water in the vicinity of the platform. The sheen, thought to be drilling mud and/or light condensate represented a volume the company estimated to be about 30 m3. Total’s preliminary assessments indicated no significant impact to the environment and dispersants are not considered necessary at that stage. Oil Spill Response Limited (OSRL) had been alerted and evaluation of the situation was underway.
On the morning of March 31, it was confirmed that the flare on the Elgin Platform had extinguished itself, and Total reported preparations of operations to regain control of the leaking well. At that time, Total estimated the lead to be around 200,000 m3 of gas per day.
On April 5, a team of Total experts and specialist contractors boarded the Elgin complex and spent nearly four hours gathering preliminary information that was used to assist in preparation for deploying the necessary equipment to perform a well control operation.
During the reconnaissance mission, visual inspection confirmed that the leak is coming from the G4 wellhead at WHP deck level. In addition, an ROV survey confirmed no underwater gas leak. In parallel, preparations were underway for the drilling of a relief well and a backup relief well.
The Eglin leak brings up a number of questions concerning how well the industry manages both known challenges such as high pressure and temperature reservoirs as well as dealing with the unexpected.
As we go to press, the situation is stable and progress has been made. We’re keep an eye on Total’s reports and will follow up in later editions.