The industry has been calling for more innovative solutions subsea, including resident remotely operated vehicles (ROVs) and autonomous underwater vehicles (AUVs) that can stay down for longer with increased battery life and without need of a support vessel. Oceaneering recently took up this task for a major North Sea operator.
Advancing Subsea Residency - Oceaneering aims to make ROVs and AUVs that are reliable, efficient, and autonomous with less required maintenance
Our first generation resident vehicle, the E-ROV (Empowered ROV) is a self-contained hybrid (electric and hydraulic) work-class, battery-powered vehicle that can carry out inspection, maintenance, and repair (IMR), commissioning and underwater intervention activities.
The E-ROV system was modeled after Oceaneering’s eNovus ROV, which uses an electric propulsion system with state of the art electric controls and intelligent diagnostics. The E-ROV system is a hybrid because it uses a hydraulic power pack to support its manipulator functions. Currently, no electric manipulators are available to provide the lifting capacity of currently available hydraulic arms. The goal is to one day achieve a fully 100% electric E-ROV system.
The E-ROV system includes a cage-mounted 100kW battery pack and tether management system, as well as a communications buoy, which hosts an antenna mast to improve signal reception and battery power to support communications transfer. The E-ROV system can be controlled from Oceaneering’s onshore mission support center with communication provided via 4G/LTE broadband network.
The E-ROV can be placed subsea by a vessel of opportunity with a self-deploying buoy, and it can be recovered by a vessel of opportunity and redeployed to another location within 48 hours.
Both the cage and ROV include advanced battery technology optimized to handle peak power consumption. While the E-ROV is battery-operated, it could be connected to a subsea power source in order to have an unlimited duration. Subsea residency, via current battery life, is designed for three months, but work to extend this is ongoing. Oceaneering’s next-generation vehicle will be designed for to last for six months.
The E-ROV’s true battery life, however, depends on the intervention work scope being performed. If the job is observational, then the system will use less power and will have a longer life cycle. If the job requires a manipulative or an injection skid intervention, then the system will need to use more battery power, which will result in a shorter work life cycle.
System development, manufacturing, and pool testing were completed in early 2017 at Oceaneering’s facilities in Stavanger, Norway. Shortly thereafter, a pilot test was conducted in the North Sea with the system deployed via an IMR vessel. It was stationed subsea for three weeks, in which time it performed various operations, with the main scope of work operating a valve on a Christmas tree. Oceaneering maintained continuous, uninterrupted control.
Oceaneering received a three-year contract with options from the North Sea operator in which the E-ROV will be deployed in a variety of locations and work scopes, servicing multiple fields.
The E-ROV is one of many innovations underway. Oceaneering’s next resident vehicle, the Freedom ROV, will be supported by a docking station at seabed and will have a hybrid functionality that will enable it to operate in two modes: remotely piloted via tether to provide real-time control – or operated in an autonomous and tetherless mode, using battery power.
The Freedom will be able to inspect miles of flowlines or remote wellheads as it flies around the field. The vehicle, like the E-ROV system, would be remotely piloting from a mission support center while in tethered free-swimming mode. While in autonomous mode, free of the tether, through-water communications will allow the vehicle to be flown real-time.
Later this year, Freedom will undergo sea trials at the Norwegian University of Science and Technology (NTNU) testing center in Trondheim, Norway.