Electric Work-Class ROVs
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As offshore oil and gas developments move into deeper waters and harsher environments, demand is growing for innovative subsea solutions that not only deliver greater reliability and performance but also address the need to protect the environment. Elsub Technologies is focused on meeting these challenges with the commercial introduction of its 200hp ELSUB electric work-class ROV.
Elsub Technologies is a wholly-owned subsidiary of the Norwegian AAK Group. The AAK Group has 30 years of experience in providing integrated maintenance, repair and inspection services and products to mobile rigs and offshore installations worldwide.
Electrical-powered work class ROV
In early 2007, the initiative was taken to break with long-established practice in the ROV industry and develop a multi-purpose, electrically powered work-class ROV, the 'ELSUB', which would deliver class-leading performance and reliability with the smallest possible environmental footprint.
AKK Subsea commenced the development programme at the beginning of 2008 with the creation in Stavanger, Norway, of an international, multi-discipline team of design engineers, experienced ROV pilot / technicians and specialist subsea equipment suppliers.
Field testing of the ELSUB began in late 2008 in the fjords in the Stavanger region down to depths of 458m, and continued into early 2009. The resulting success of this test program led to the decision in late 2009 to complete the ELSUB to commercial specification and to offer this to the market.
Since January 2010 the first ELSUB has been operational on a long-term rental contract on a drill-ship located off the coast of Venezuela. As of the end of March 2011, the ELSUB has completed over 220 dives of varying work scope and has accumulated more than 1,200 hours subsea in often challenging operating conditions with outstanding reliability and continuity of service.
Simple, rugged and compact ROV with 200hp
For many years the work-class ROV market has been served by ROV systems based upon electro-hydraulic propulsion principles with electric power being converted to hydraulic power on the vehicle itself; this power then being used to drive the hydraulic thrusters. However, this approach has a number of disadvantages, among which are high-component density and complexity on the ROV, inefficient conversion of power, and the requirement for a significant volume of hydraulic oil to be carried within the system.
Fundamental to the ELSUB project was the philosophy of achieving a minimal component count on the ROV itself, and locating the more sensitive electronic and power control systems topside in keeping with the design goals of simplicity, reliability and ease of maintenance. This led to the adoption of a custom-built, multi-conductor umbilical, which enables each electric thruster to be directly powered and controlled independently from topside and provides additional channels of controlled electrical power to the ROV for auxiliary equipment and tooling. Highly efficient transmission and power conversion is achieved by the use of 3,000V variable-frequency alternating current in each power channel.
This approach results in a simple, rugged and compact ROV that can currently deliver over 200hp of useable power at the vehicle for propulsion and auxiliary applications as required. The high efficiency of the electric power system results in at least a 40% reduction in the topside power consumption versus conventional WROV's of comparable performance.
Electric-powered winch and handling units
Elsub Technologies is now extending the electrical power concept to the AHC winch and TMS handling units, which will be delivered with new systems currently in production. This will further reduce the demand on topside power facilities. Along with design improvements based on our experience to date, the goal of offering a class-leading WROV with impeccable 'green' credentials is now achievable.
Elsub Technologies' principal business model is to build, own and operate the ELSUB to provide a wide range of ROV services, including drill support, survey, IMR and medium-duty construction services to the international offshore industry.
Available White Papers
Electric-Propulsion Work-Class ROV White Paper The ELSUB electrically powered WROV system delivers outstanding reliability and versatility in a powerful and compact package. The electric thrusters are individually powered and controlled from topside, offering a significantly reduced environmental impact by reduction of hydraulic oil volumes while maintaining high power efficiency.