Autonomous and ready to work

Elaine Maslin profiles some of the projects moving forward that pledge to deliver autonomous underwater vehicles for life of field operations.

Modus’ AUV launch and recovery system, designed and built by Osbit. Photo from Osbit.

UK-based Modus Seabed Intervention and Sweden’s Saab Dynamics agreed last year to jointly develop the operational use and applications of the Saab Sabertooth hybrid autonomous underwater vehicle/remote operated vehicle (AUV/ROV), including applications in life-of-field subsea survey and inspection.

Modus then ordered the first of a planned fleet of Sabertooth vehicles, which launched in Q4 2016. Also, late 2016, subsea engineering and technology firm Osbit delivered a floating launch dock and a sea parking garage for Modus’ Saab Sabertooth hybrid AUV. Water trials of the docking systems have been successfully completed.

Sabertooth can be operated in both fully autonomous (AUV) and tethered (ROV) modes enabling fully flexible dual operations from one platform. The idea is for the vehicle to be used across a range of subsea operations, from site investigation surveys through to decommissioning support, but a major focus is on its application in long-term subsea operations and maintenance. The deepwater rated unit is also capable of providing light intervention support.

The floating launch dock, which can be used when the AUV is both tethered and untethered, enables the operator to deploy the vehicle and also return it to the deck of the ship. The dock is submerged in the sea as the AUV leaves and returns, and partially fills with air to allow collection from the water surface.

The subsea parking garage provides a safe haven for the AUV when not operational and allows the operator to deploy the AUV at a specific location without having to maintain a presence there. When it has completed its automated tasks, the AUV returns to the garage and safely awaits recovery at a time convenient for the operator.

Modus says that the system has been equipped with additional batteries for extended autonomous endurance and with increased thrust for high speed survey, making it ideal for both high current and deepwater applications.

In the vehicle are a suite of advanced survey sensors including the latest Edgetech 2205 combined triple frequency sidescan sonar, co-located swath bathymetry and sub bottom profiler, HD video/stills cameras, IXBlue Phins3 INS, and RDI workhorse DVL. To manage data acquisition, navigation and processing of sensor data the software package QINSy (quality integrated navigation system) from Saab QPS is fully integrated. The vehicle has been configured to allow additional sensors, such as standard MBES, cathodic protection probes, laser scanning systems and cable trackers to be quickly integrated against project specific applications.

AIV

After completing a test mission for Shell in the North Sea in 2014, in addition to simulation and testing programs at the Underwater Centre at Fort William, Scotland, Subsea 7’s autonomous inspection vehicle (AIV) was due out on a live job for Shell in November 2016, said Paul Yeats, products division, director, life of field services at Subsea 7, at Offshore Energy in Amsterdam.

Subsea 7 has been developing the AIV in collaboration with Edinburgh’s SeeByte, which provides smart software solutions for unmanned underwater vehicles. Subsea 7 says that the AIV has the potential to revolutionize life-of-field projects by providing operators with a cost-effective, low-risk, inspection system to aid field survey, integrity management and intervention activities.

The AIV has been designed with an ability to recognize and respond to its surroundings, being able to correct its trajectory in real-time, based on information it gathers from its onboard sensors.

The AIV could operate from a host facility, such as a floating production vessel or platform, as well as from infield support vessels or mobile rigs. Crucially, it has no tether, which means its maneuverability is not restricted and it can access confined spaces. It comes with an array of navigation tools and sensors, powered from its onboard battery, which enables up to 24 hours’ autonomous inspection, Subsea 7 says.