Elgin platform

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  9. Environmental disasters
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  12. North Sea energy
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  14. Oil platforms in Scotland
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30px External images
16px Elgin platform photographed in 2009. Source: Flickr image.

The Elgin platform is a gas/oil platform located in the North Sea at 240 km (129.6 nautical miles) east of Aberdeen (Scotland) which provides the processing and control facilities to the Elgin–Franklin fields. It is operated by Total.

The Elgin installation consists of two separate platforms connected by a 90 m (300 ft) bridge: a wellhead platform (WHP) which houses the wells and the process, utilities and quarters (PUQ) platform.

The PUQ is pile mounted jack-up design located 93 m above the seafloor. The PUQ hosts hydrocarbon processing facilities, control systems and accommodation for a crew of 97 persons. The structure was built by BARMAC in Nigg, Scotland, and installed in July 2000. The facility has a processing capacity of 516 million cubic feet per day (14.6×10^6 m3/d) of gas and 175 thousand barrels per day (27.8×10^3 m3/d) of condensate.[1]

The well head platform is based on a fixed steel jacket and has 12 well slots. The WHP has no installed drilling facilites (derrick, etc). Well drilling and workover services are provided when needed by a jack up rig which operates in tender mode.

Technical characteristics

  • high pressure / high temperature (HP/HT) well
  • well depth: 5,500 m (3.4 mi)
  • pressure range: 600 – 1100 bar
  • operational pressure: 860 bar
  • fluid temperature: 193 °C (379 °F)
  • sea floor depth: 93 m (305 ft)

March 2012 gas leak

On 25 March 2012, at the Elgin Well head platform (a separate bridge linked unit) a gas leak occurred within well 22/30c-G4 during operations to plug and decommission the well.[2] No injuries were reported and 219 non-essential personnel were evacuated from the PUQ and the adjacent Rowan Viking jack up rig (which was performing the decommissioning work on the 25 March. The remaining 19 personnel were evacuated later on 25 March 2012. Methane gas was released into the environment as was between 2 and 23 tonnes of condensate which formed a sheen measuring approximately 6 nautical miles (11 km; 6.9 mi) in length. The HM Coastguard have declared an exclusion zone for ships (2 nautical miles (3.7 km; 2.3 mi)) and aircraft (3 miles (4.8 km)). Shell E&P has evacuated non essential staff from the Shearwater platform located in block 22/30b 6 km (3.2 nmi) from Elgin.[3]

At the time of the incident the Elgin/Franklin field was producing about 9% of the UK gas production.

According to Total, the origin of the gas leak was an unexploited chalk reservoir layer of the Hod formation located at a depth of 4 500 m above the main reservoir. Analyses have shown the absence of significant concentration of hydrogen sulfide in the gas. The Hod formation had been isolated by steel casing during drilling in 1997. On 25 February an increase in pressure was observed in the C annulus within the well and remedial operations started on 4 March. Total believe that the C annulus failed and gas was observed leaking from the 30 inch conductor. (Ref [1])

The platform flare burning the volatile emanations from natural-gas condensate residues still present aboard the platform after its emergency shutdown was alight till 31 March 2012 representing a potential risk of ignition for the gas cloud if wind direction should change. Total announced the flare was spontaneously shut down on Saturday 31 March 2012 after exhaustion of the volatile residues within the PUQ processing facilities.

An inspection team comprising 8 people from Total and Wild Well Control (a specialist well control company) boarded the Elgin platform on 5 April 2012 to gather information about the state of the platform. The team left safely after 4 hours (ref [2])

During April 2012 a diverter assembly was installed around the G4 well head. This diverted the leaking gas (estimated then at 200,000 m3 per day or 7 mmcfgd) away from the platform in a controlled manner enabling well control operations to begin (ref [3]). Two vessels were working on repairing the leak in May 2012: The West Phoenix semi submersible rig was working on the "top kill" operation. This will involve pumping weighted drilling mud into the well via the wellhead assembly. A relief well, G4-K1 is being drilled to "bottom kill" the well by the Sedco 714. Eleven monitoring overflights by surveilence aircraft of OSRL (Oil Spill Response Limited) of the area were made in early May the flow rate from the well was estimated at that time to be 50,000 m3 per day or 1.8 mmscfgd (ref [4]).

"Top kill" well intervention work started on 15 May and on 16 May Total announced that the leak had been stopped and they are monitoring the well to confirm success. (ref [5])

See also

References

This article uses bare URLs for citations. Please consider adding full citations so that the article remains verifiable. Several templates and the Reflinks tool are available to assist in formatting. (Reflinks documentation) (April 2012)
  1. ↑ http://www.totalepmediacentre.com/files/Elgin%20Franklin%20August%202010.pdf[dead link]
  2. ↑ http://www.totalepmediacentre.com/index.cfm?encstrg=8%3E%2BJ23%21%3A%3DT%24W%5DB%2DD6E2V4C591D%29%3A%5B%21%5C%5C%2B%0A[dead link]
  3. ↑ BBC News (2012-03-28). "Gas leak platform flare 'burning'". BBC. http://www.bbc.co.uk/news/uk-scotland-north-east-orkney-shetland-17522086. Retrieved 2012-03-31.

External links

Coordinates: 57°10′N 2°00′E / 57.167°N 2°E / 57.167; 2{{#coordinates:57|10|N|2|00|E|type:landmark_source:kolossus-frwiki|| |primary |name= }}de:Elgin Wellhead Platform fr:Fuite d'Elgin no:Elgin brønnplattform


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