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New subsea well-capping device to bolster UK emergency underwater oil spill response capability

The OSPRAG well-capping device. Click to enlarge.

UK Energy Minister, Charles Hendry MP, unveiled a well-capping device developed by the Oil Spill Prevention and Response Advisory Group (OSPRAG) at the SPE Offshore Europe 2011 conference in Aberdeen.

The cap works by shutting in and holding pressure on an uncontrolled well and uses a choke and a series of valves which close down and stop the flow of hydrocarbons into the marine environment. The well-capping device was built in order to seal off an uncontrolled subsea well in the event of a major well control incident—i.e.., similar to that of the Deepwater Horizon in 2010— thereby reducing environmental damage and buying valuable time for engineers to develop a permanent solution to seal the well.

Capping device key facts
It can quickly be deployed:
At the widest possible range of wells and oil spill scenarios which could occur in the UKCS, including West of Shetland
To various points of the subsea stack
At water depths of between 100m and 3,048m (328ft to 10,000ft)
In wave heights of up to 5m (16ft) depending on the vessel/rig used
From a wide variety of multi-service vessels or drilling rigs
To wells flowing up to 1,034 bar (15,000 psi) in pressure and 121°C (250°F) in temperature
Even where there is a high content of hydrogen sulfide present
On to a well flowing up to 75,000 barrels a day
Length 4.26m
Width 3.97m
Height 7.14m
Footprint 15.8m²
Weight approx. 40 tonnes

The major piece of new equipment is designed to be a key element of the UK offshore oil and gas industry’s oil spill response capability; it has been constructed, tested and is available for deployment.

The device was constructed specifically for subsea wells in the United Kingdom Continental Shelf (UKCS). Its modular design means it can be attached to various points of subsea equipment and deployed to the widest possible range of subsea well types and oil spill scenarios which could occur, including in the deep waters and harsh conditions west of Shetland.

The cap is rated for deployment in water depths up to 10,000 ft (3,048 meters) on wells flowing up to 75,000 barrels per day at 15,000 psi. This is a much greater depth than any of the deepest wells in the UKCS.

Its portable size and weight also makes it quickly deployable from a wide range of vessels, even during short weather windows.

The capping device was designed and manufactured over a period of only seven months; OSPRAG says this was achieved through access to pre-existing equipment systems, a streamlined project management approach and close collaboration with the industry’s global supply chain.

The device has now completed factory acceptance and system integration testing and will be handed over to Oil Spill Response Limited, which will store it in readiness at an operational base in the north east of Scotland with the appropriate deployment capabilities in the event it is required.

Animation showing the OSPRAG well capping device, how it works and how it can be deployed. Click to enlarge.

The decision to construct the cap came as a result of a recommendation by the Oil Spill Prevention and Response Advisory Group (OSPRAG), the body set up by the industry, its regulators and trade unions immediately following the Deepwater Horizon incident in the Gulf of Mexico in April 2010.

The vast majority of UKCS operators participated in the development of the device following focused discussion and collaboration. There was overriding agreement on the need to deliver this additional piece of assurance as soon as possible.

The design development was overseen by OSPRAG’s Technical Review Group, working with BP, which agreed to project manage the detailed design, procurement and construction phases, with support from engineering services firm Wood Group Kenny. The device was commissioned by the industry’s specialist organization, Oil Spill Response Limited, and was built by Cameron Ltd in Leeds.

All of OSPRAG’s work will be presented at the OSPRAG Summit on 21 September 2011 in Aberdeen.


Henry Gibson

Several enclosed lenses of explosives can be built into an external casing when the well is started. They can be detonated as needed to weld the well casing shut. The technology was developed in 1944 for detonating plutonium, but sealing pipes was tested first. ..HG..

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