The standalone DC choke package, in combination with metering tools and flow management software, allows manual or automatic positioning. (Image courtesy of Cameron)

The world’s first all-electric subsea production system came on stream in September of 2008 as part of the K5F project developed by Total E&P Nederland B.V. (TEPNL) in the Dutch Sector of the North Sea. The CameronDC system meets Total’s K5F field requirements and includes a three-well template/manifold with a two-well initial installation, with the option for a third well. The all-electric control system is configured for a four-well application, designed to accommodate the fourth tree as a step out.

The template/manifold is installed in 131 ft (40 m) of water and is controlled from an existing platform 11.2 miles (18 km) away. Production is piped back to an unmanned platform 6.2 miles (10 km) away.

With zero hydraulics, CameronDC solves environmental challenges while delivering reliability, availability and maintainability. Key topsides components for the system include a master control station, which controls and monitors the subsea system and four electrical power and communication units, two for each tree. The topsides umbilical termination unit terminates the main umbilical topside.

Without the burden, limitations and expense of hydraulics, CameronDC delivers key advantages over conventional systems. Savings come in several areas, including cheaper umbilical; cheaper umbilical installation; host facility space and weight savings; and the elimination of the purchase, maintenance and disposal of hydraulic fluid.

The system overcomes the limitations of long step outs and water depths encountered with hydraulic systems. In fact, step-out distance is virtually unlimited and the system is compatible with ultra-deepwater depths, including 15,000-plus ft (4,572 m).

Because the CameronDC system is all-electric, much of the conventional electro-hydraulic equipment has been either simplified or eliminated. Most importantly, the size of the umbilical is greatly reduced. Moreover, hydraulics pose a large environmental risk. The system’s all-electric technology provides full compliance with zero tolerance of fluid emissions by eliminating the risk of hydraulic leaks and other environmental problems associated with hydraulic fluids.

At steady state, the system’s power requirement is comparable to that of a light bulb. Even at peak, it uses only the power required by common household appliances — 1/1000th of the power consumed by a subsea multiphase pump. The topside unit supplies 3kVDC to the subsea power regulation and communication module. During actuation, the current is increased to the required level. The module provides the required power to the electric subsea control module, which commands the valve to open.

Once open, only minimal power is needed to hold it open. The topside unit then reduces the current via power management software.

CameronDC has fewer parts than equivalent solutions, and the parts that it does have are more reliable, making the entire system more reliable. There are no solenoids, directional control valves, hydraulic couplings, filters, pressure sensors, batteries, or accumulators.

Finally, in addition to high-speed communication and real-time condition monitoring, the system is able to track performance over time. CameronDC gate valves are fail-safe close, using a spring-powered mechanism — a unique competitive edge. Valves are held in the open position by low-voltage current. If power is cut, the spring automatically close the valve.

The CameronDC system for the K5F installation features full redundancy throughout. During operation, the electrical signal moves through the umbilical to the UTA where it is routed through the PRCM to the tree-mounted ESCM and then into the actuator. The signal then returns into the seawater return system via the cathodes.

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