on near the production equipment clusters. Once the Swimmer AUV shuttle is on its docking station, the Swimmer ROV can be remotely controlled from the surface via the field control umbilical. The operator has the hand over of the Swimmer ROV just like for a conventionally MSV-deployed ROV. In this configuration, the Swimmer ROV is powered by the FPSO (or from shore), and intervention is performed conventionally with real time data and video transmission. The Swimmer can remain deployed subsea for several consecutive weeks. Since the Swimmer performs all light IMR operations, the MSV can be dedicated to operations requiring handling of heavy equipment and modules. In this way, Swimmer introduces flexibility into the operations and reduces the overall opex.Swimmer concept was invented by Cybernetix in 1997. The feasibility of the concept was demonstrated successfully by Cybernetix and partners (IFREMER, the University of Liverpool) in October 2001 during full-scale sea trials. The Swimmer AUV prototype was programmed to autonomously reach and securely land onto a docking station at 100 m (328 ft) water depth to tap energy and communication for the Swimmer ROV. Following this demonstration, Cybernetix, with Statoil and Total, worked several cases to evaluate the economics of a Swimmer system for various fields. This work to a joint industry project (JIP) among the three partners to further study the technology. Phase 1 of the JIP showed the financial viability for future field developments, and recommended the extension of its scope of work to include pipeline survey and inspection.parallel, Cybernetix developed the Swimmer to a level of reliability required by the oil and gas industry. In particular, R & D efforts aimed at a robust and efficient docking algorithm, positioning and navigation systems, and subsea power and data transmissions. More recently, Total and Cybernetix are targeting the development and qualification of a Swimmer system for offshore Angola block 17.FEATURESSwimmer system is composed of both fixed and mobile assets. The fixed assets are part of the offshore field infrastructures and include the following:
? Subsea docking stations
? Subsea power and data cables embedded into the field control umbilicalconsoles integrated into the FPSO control room. The hybrid vehicle and the associated IMR tools form the mobile assets and include the following:
? AUV shuttle
? Light Work-ROV equipped with two manipulator arms
? Work-ROV TMS integrated into the AUV shuttle
? ROV tools for light IMR operations.Swimmer is designed to stay deployed subsea for up to three months. The current design depth is 1,500 m (4,921 ft) but can be extended to 3,000 m (9,842 ft). The AUV shuttle operating range is 20 km (12 mi) in the standard configuration, but can be extended to 50 km (31 mi), and cruising speed is up to 2 knots. Once docked, the ROV excursion around the docking station is in the 200 m (656 ft) range. The IMR tasks that can be performed by the Swimmer ROV include the following:
. Valve operation
. Cleaning
. Global, close, and detailed visual inspection
. Wall thickness measurement
. Cathodic protection measurement
