Sea Technology

JUL 2017

The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community

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14 st / July 2017 more than 300 hotels and restaurants located on the island. The island's power supply relies on a connection made by a system of cables first installed in the 1980s. Today there are four cables: only one of them is in service (IS), and three are out of service (OOS). Their positions were unknown; plus, fragments of cables existed due to maintenance car- ried out through the years. O ne of the most effective methods of protecting subma- rine energy and telecommunication cables from dam- age caused by other seabed users is to bury them on the seafloor. However, the success of this burial is strongly de- pendent on proper planning and the seabed geology along the cable route. Route surveys for cable-laying projects are conducted with a suite of three basic systems: multibeam echosounders (for morphological mapping); side scan sonar (for definition of superficial sedi- ment distribution and location of other cables or pipelines, shipwrecks, anchors and man-made debris of significant dimension); and high-res- olution seismic (for investigations below the seafloor, including shallow gas and rocky base- ment). Magnetometers may play an important role in these projects. Additionally, geological cores for geotechnical testing and correlation with geophysical attributes may be collected. We used a geophysical approach based on multifrequency, high-resolution seismic survey for the installation of an energy cable in a rela- tively small area on the southeast coast of Rio de Janeiro, Brazil. The area is environmentally sen- sitive and is a site for fishing and tourism, with intense boat traffic. There are also two important harbors receiving very large bulk carriers and oil tankers. Site and Project Background Ilha Grande is the biggest island along the coast of the state of Rio de Janeiro. It has ap- proximately 3,000 inhabitants, schools, hospi- tals, a fire department and a police station. The economy is based on fishing and tourism, with Scouting for Energy Cable Route For an Island off Rio Multifrequency, High-Resolution Seismic Survey for Cable Planning By César Félix • Dr. Arthur Ayres Neto • Dr. Luiz Antonio Pereira de Souza Examples of the multifrequency, single-channel seismic survey method.

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