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Wellhead Control Technology

Gyda field re-development focuses on ease of maintenance and space saving. The Norwegian Gyda field, located between Ula and Ekofisk in the southern part of the North Sea, proven in 1980 started production in June 1990. Developed with a combined drilling, accommodation and processing facility with a steel jacket, the facility supplies approximately 14,000 barrel of oil per day. The Gyda field is considered amongst many, as a mature field in terms of current reserve depletion. Gyda is ideally suited to owners Talisman Energy’s North Sea strategy, which focuses on mature and small field development, with ample potential for significant new investment.

Part the estimated CDN$200 million investment was a drive to increase efficiency, while increasing productivity. In the Autumn of 2007 Talisman approached Sørco, with the view to utilise their experience and expertise in upgrading the performance of oil and gas facilities in operation. After going through overall specification with Talisman, Sørco approached Haakon Ellingsen to produce 8 Wellhead control panels for the GYDA platform.

As part of the specification, Talisman had a requirement for a compact design but with serviceable components. Haakon Ellingsen designed, manufactured and  tested the wellhead control panels. UK manufacturer Midland-ACS were chosen as the preferred partner due to their experience in design, engineering capabilities and their total solution status. Over the course of meetings with Sørco and Haakon Ellingsen it was decided that a manifold solution would produce the best results, while conforming to a variety of regulations and the express requirement of Talisman for a compact design.

As the appointed manifold provider Midland-ACS assumed responsibility for engineering, procurement co-ordination, fabrication and assembly, as well as the testing of the assembled manifolds. In order to add further value all of the required design work was completed by their own engineering team. Due to the nature of the suggested manifold solution several gains in a number of keys areas were achieved including less tubing, space saving, weight and maintenance. Using the latest 3D Solidworks modelling to design the system and check that the space was serviceable for maintenance purposes, their engineers also animated and analysed the flow through the manifolds to spot efficiency gains wherever possible, as well as identifying potential leak points and eliminating them. A highly desirable feature in exposed and difficult to access areas on oil rigs.

The design was split into 2 parts, whereby Ellingsen would be responsible for the complete design of the panel itself and Midland-ACS would design the manifold solution.

Manifold Specs
Due to the environmental conditions associated with working the North Sea and to ensure the longevity and long term reliability of the manifolds, they were constructed from 316 Stainless Steel, widely renowned as being a material of choice for both hazardous area and industrial use.
Consisting of two wellhead control manifolds for AMV and ASV control the manifolds are made up of 8 and 16 valve multi-stations with the capacity for future stations. The manifolds have a maximum operating pressure of 370 bar with a nominal flow rate of 5 l/min. As part of the design, integral modules for isolation and check valves were also incorporated allowing a quick and easy change out of any individual solenoid valve in the event of a problem. This design means that the whole panel does not need to be shut down only that particular channel, resulting in diminished losses in production and shut down time.

Controlling the manifolds are Midland-ACS’s well known low power consumption, 3/2 normally closed, DN3 series hydraulic valve. The valves feature auto-reset and manual resets for PSD and ESD control. They are also compliant to EExme II T4 and ATEX II 2 G standards with  a maximum operating pressure of 690 bar.

The completed manifold and their solenoid operators were subject to rigorous test procedures in accordance to Quality Assurance standards, FMEA tool deployed to drive control plans and internal audit schedules prior to despatch. The manifolds were then supplied to Ellingsen with test reports and full documentation packs.

Panel Specs
Space on any platform is always at a premium, therefore as part of the program to reduce space used, while increasing efficiency but for less over all weight, Ellingsen designed the panels to be able to control up to 8 wellheads. This signified a big step forward whereby previously there would be 1 panel per wellhead for control. Currently there are solenoids are in place to control 6 wellheads per panel, with the option for further expansion should future production require it.

Ellingsen produced 2 panels in total weighing 500 kilos (1102 lb) each. As a first for the Norwegian company, the panels represented the 1st time they had designed and made such complex control panels. Making use of clean design principles with a key view being ease of maintenance, the power, electric and hydraulic signals were placed on right of the panel with the output signal on left.

It was deemed necessary and an important part of the panel design, to have the RMA valve on deck to act as a 2nd barrier between well and platform. In uncontrolled situations the RMA valve could shut the situation down in a matter of seconds, providing a better safety system based on regulations provided by the Norwegian government. The panels in addition were designed to conform to incoming regulations and NORSOK standards.

To thoroughly show off the level of quality of the design and engineering work that had been done, on the factory acceptance inspection of the completed panel assembly, Sørco made absolutely no comments. Another first for both Midland-ACS and Ellingsen.
 
Images produced care of and with permission from Haakon Ellingsen.
www.midland-acs.co.uk
For further information contact: Sales & Marketing Department
Midland-ACS, Patrick Gregory Road,
Wolverhampton, WV11 3DZ
Tel: +44 (0)1902 305678
Fax: +44 (0)1902 305676

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