OneSubsea’s all-electric subsea production control system represents the first of its kind. The system—formerly known as the CameronDC System—first came online in September 2008 and is able to address issues related to functionality, long step-outs, water depth limitations and common failure modes of conventional electrohydraulic (EH) MUX systems. The technology, which also can help prepare operators for the digital oil field, won Hart Energy’s 2009 Meritorious Award for Engineering Innovation in the production systems category.

Since the system’s introduction and initial use as part of the K5F project, OneSubsea has received a purchase order for delivering a third tree for the field, located in the Dutch sector of the North Sea. “This extension to the 2008 scope is currently under construction and builds on the performance and lessons learned during the initial installation,” said Jan van den Akker, control systems product manager for OneSubsea. The system’s all-electric controls can offer advantages in functionality by providing a more intelligent way to control chokes whereby field data are instantly driving the choke position to allow certain flow regimes. A standard choke may be too slow and not geared up for the increased use over the life of the field.

The system also allows longer step-outs. “With our patented technology there are no real limits when it comes to distance, compared to the challenges faced when using a control fluid in offsets longer than 200 km [124 miles],” van den Akker said.

Additionally, the company’s all-electric actuators are not affected by water depth by design, a significant trait when considering that the size of a hydraulic actuator is heavily influenced by the water depth in which it operates.

Many failure modes in traditional systems stem from seal degradation or control fluid property issues like contamination. The company’s all-electric system does not use any hydraulics but instead uses electronics and electric actuators. “Similarly to other industries, electronics reliability is easier to achieve and control,” van den Akker said.

With more and more equipment operating off the seafloor, future installations will require more data to implement software models that read diagnostic data, support preventive maintenance regimes and allow the use of more sophisticated production optimization tools. With preventive maintenance set to play a larger role than today’s reactive behavior, it is more important than ever for operators to be prepared for the challenges of the digital oil field. “The implementation of all-electric technology from OneSubsea will provide significantly more data that can be used to implement intelligent field management tools,” van den Akker said.

Since the system’s introduction, the company has completed the development of a second-generation all-electric system. “The inputs come from lessons learned, standardization targets and the drive to reduce costs,” van den Akker explained. “Our latest generation is as modular as OneSubsea’s current EH MUX Control System, and it shares the same communication network using fiber optics and our standard protocol.” The updated system has been optimized for more field scenarios and more capabilities such as simultaneous actuator operations.

While the first generation needed two modules per tree, the latest version has been condensed to a single module that shares the same footprint as the company’s standard EH MUX subsea control module. “With these enhancements, an all-electric production control system is as cost-effective as our standard EH MUX system, while further enhancing the reliability of the complete system,” van den Akker said.

OneSubsea is a company jointly owned by Cameron and Schlumberger. Visit onesubsea.com.