10 kV Subsea Cables: Filanovsky LSP-1 to Grayfer Platform
Development of Detailed Design Documentation, Procurement of Materials, Installation (Laying) of Subsea Power Cable Lines, Cables and Sensors for the Subsea Components of the Geodynamic and Hydrological Monitoring Systems at the V.I. Graifer Field (Phase 1 Development)
All projectsAs part of the project, two 10 kV subsea power cable lines, as well as subsea lines for the geodynamic and hydrological monitoring systems, were laid along the route from the LSP-1 ice-resistant fixed offshore platform at the V. Filanovsky Field to the ice-resistant fixed offshore platform at the V.I. Graifer Field.
Detailed design documentation and method statements were developed in-house, taking into account the requirements for high-quality and safe execution of works in the vicinity of existing utilities. The East River cable-laying vessel was engaged for offshore operations and specially upgraded for the project. Prior to commencement of the works, the vessel was equipped with the necessary cable transportation and laying equipment, including stationary cable tanks and wheel-type cable tensioners. Installation of the power cable lines was preceded by excavation of pits in the vicinity of the platforms. Part of the works was carried out on an operating platform in compliance with industrial safety requirements.
Following installation on the seabed, the cable lines were buried to a depth of more than two metres using trenching equipment. The works were performed in accordance with the design documentation, applicable regulatory requirements, and DNV requirements for Marine Warranty Survey (MWS).
Key Parameters:
Main Stages of Work:
- Pre- and post-lay route surveys using a multibeam echosounder and side-scan sonar (R2Sonic 2022), magnetometer, EdgeTech SB-216S sub-bottom profiler, and C-Nav 3050 DGNSS positioning system.
- Excavation and backfilling of subsea pits adjacent to the platforms using a bucket dredger with a hopper barge; final excavation works performed by divers using water-jetting equipment and an HY85B pump with an EXHY20 excavator attachment.
- Diver-assisted installation of subsea cable sections on the jacket structure of the LSP-1 platform.
- Power cable laying using a cable-laying vessel equipped with stationary cable tanks and wheel-type tensioners; positioning using the DP-1 Sirenha system in conjunction with Hypack.
- Pulling cables through subsea cable conduits using a steel pulling wire and self-tightening cable pulling stocking; cable exit procedures developed using 3D models.
- Burial of cable lines using ST-2 (ETA LTD) and OTTER-2 trenchers by directed water jetting, with diver control and monitoring via USBL and roll/pitch angle measurements.
- Installation of subsea equipment for the geodynamic and hydrological monitoring systems.
- Integrated testing of the cable lines.
