The Norwegian Gyda oilfield, in the southern part of the North Sea, started production in June 1990. Developed with a combined drilling, accommodation, and processing facility with a steel jacket, the operation supplies approximately 14,000 barrel of oil per day. The Gyda field is considered mature in terms of current reserve depletion, and as such, 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.
In fall 2007, Talisman undertook a drive to increase efficiency while increasing productivity. Haakon Ellingsen was approached to produce 8 wellhead control panels for the Gyda platform. Talisman required a compact design with serviceable components. Haakon Ellingsen designed, manufactured, and tested the wellhead control panels. UK manufacturer Midland-ACS was chosen as the preferred partner, and a manifold solution was settled on as likely to produce the best results while conforming to a variety of regulations and Talisman’s requirement for a compact design.
Midland-ACS assumed responsibility for engineering, procurement coordination, fabrication and assembly, as well as testing of the assembled manifolds. Midland’s engineering team completed all of the required design work. The manifold solution yielded gains in a number of keys areas, including less tubing, space saving, weight and maintenance. Using the latest 3D Solidworks modeling to design the system and check that the space was serviceable for maintenance purposes, the engineers also animated and analyzed the flow through the manifolds to spot efficiency gains wherever possible, as well as identifying and eliminating potential leak points -- a highly desirable feature in exposed and difficult-to-access areas on oil rigs.
The design was split into two parts, with Ellingsen responsible for complete design of the panel itself and Midland-ACS for the manifold solution.
Designing the Manifolds
To accommodate environmental conditions in the North Sea and to ensure the longevity and long-term reliability of the manifolds, they were constructed from 316 stainless steel, a material of choice for 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 multistations with the capacity for adding stations. The manifolds have maximum operating pressure of 370 bar with nominal flow rate of 5 l/min. Integral modules for isolation and check valves were incorporated as part of the design, allowing quick and easy changeout of any individual solenoid valve in the event of a problem. Thus the whole panel does not need to be shut down -- only that particular channel -- resulting in diminished production losses and downtime.
Controlling the manifolds are Midland-ACS’s low power consumption, 3/2 normally closed, DN3 series hydraulic valves. The valves feature auto-reset and manual resets for PSD and ESD control, and are compliant to EExme II T4 and ATEX II 2 G standards, with maximum operating pressure of 690 bar.
The completed manifold and solenoid operators were subject to rigorous test procedures in accordance with 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.
Space-Saving Panels
Since space on any platform is always at a premium, Ellingsen designed the panels to be able to control up to 8 wellheads, increasing efficiency for less overall weight. This was a big step forward from the previous setup of one control panel per wellhead. Currently solenoids are in place to control 6 wellheads per panel, with the option for further expansion.
Ellingsen produced 2 panels weighing a total 1,102 lb each – the first time the Norwegian company had designed and made such complex control panels. Making use of clean design principles with a key goal of ease of maintenance, the power, electric, and hydraulic signals were placed on right of the panel with the output signal on left.
As an important part of the panel design, the RMA valve on deck acts as a second barrier between well and platform. In uncontrolled situations the RMA valve could shut down in a matter of seconds, providing a better safety system based on Norwegian government regulations. The panels were also designed to conform to incoming regulations and NORSOK standards.