Elaine Maslin dives deeper into the all-electric subsea equation.
The K5F-3 subsea all-electric Xmas tree from OneSubsea.Photo from TEP NL (Total E&P Netherlands).
All-electric subsea installations have been on the agenda for years, if not decades. While it’s still not quite a reality, it’s closer than it’s ever been, with all electric actuators proven and in use, the first all-electric subsea Xmas tree installed and operating (OE: September 2016) and qualified subsea power distribution systems.
“The future is all-electric,” says Einar Winther-Larssen, product manager for all-electric and new products at Aker Solutions. “We see huge interest from customers working towards this type of technology.”
All-electric systems mean hydraulic lines and the hydraulic production units to support them are not required, cutting umbilical costs significantly, especially on longer step-outs. Controls and communication architecture can also be more flexible, enabling a different way of thinking, and easier expansion and or integration into other facilities, Winter-Larssen says.
Using distributed controls architecture, distributing Logic, increasing functionality on electric actuators, a central subsea electronics module (SEM) could be taken out of the system and enable such systems to merge into a brownfield without effecting the infrastructure around it, he adds. “Get rid of the SEM and you can reduce the size of the Xmas tree and manifold,” he says.
In the digital era, electrification also has its benefits. “Electric actuation and (Aker Solution’s) Vectus (subsea electronics module) enables you to get data off site, do field monitoring and optimize functionality and processes, including on Xmas trees and valves.
The Asgard subsea gas compression system, complete with eActuators and electric process control valves. Image from Statoil.
“Moving Logic or other type of computers closer to the valve we can get more information from the source. We can monitor the valve and know much more about it. We can have more data points, which can be used for making information or visualize something better.”
An all-electric world could also incorporate autonomous subsea vehicles in a more efficient way. “The first step will be all-electric systems with all the functionality we have today,” Winter-Larssen says. “The next step will be how we optimize it using remote operated vehicles (ROV) and autonomous underwater vehicles. You still want to maintain the pressure barrier and have the functionality you need to shut it down in the system. Auxiliary systems, pigging loop valves and manifold loop valves, could be managed by a sea snake (OE: May 2016) or an ROV.
“Those types of system can bring value by reducing the number of functions on the subsea production system. I don’t think we will use those types of solution on a safety solution,” Winter-Larssen says.