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    DNV develops class notation for seismic vessels

    Vessel & ROV News // October 3, 2012

    DNV has developed a new class notation for seismic vessels in consultation with key industry players such as WesternGeco, PGS and Fugro-Geoteam.

    The need to have enhanced redundancy and proper deck arrangements to ensure continuous operation without loss of speed is the backbone of the new requirements.

    "Seismic vessels contain high-end computerized technology to find resources below the seabed, and represent a key element in the value chain leading to future offshore field developments," said DNV. "Any interruptions in the ship's forward movement can complicate the seismic data processing. Continuous operations are of utmost importance.

    "With expensive seismic streamer equipment mobilized at sea, sudden loss of service speed may lead to severe consequences as damage to cables impairing the whole seismic vessel operation.

    The new notation focuses on increased availability of the vessels during critical phases of the seismic operations.

    In addition to vessel operators, DNV has consulted seismic handling and high pressure equipment suppliers to ensure that all current and future industry challenges are comprehensively dealt with.

    The new notation was released this summer and strengthens DNV’s position in the seismic classification market as the industry focuses more strongly on deepwater, frontier exploration.

    “DNV has the greatest share of this market. More than every second seismic vessel is DNV classed. By introducing the new class notation we are helping owners in this high-tech special vessel segment to meet future demands with the outmost safety and reliability,” said Jan Kvålsvold, Director for Market and Business Development.

    "The maintenance of propulsive power is a key issue. The class notation has therefore taken the DNV concept for redundant propulsion one step further so that any failure on board will not lead to loss of more than 50 per cent forward trust.

    "This is sufficient to maintain a minimum speed of a few knots and will protect any high cost air guns and streamers deployed.

    "Seismic vessels typically operate for many months continuously without seeking harbour. The class notation requires a deck arrangement that facilitates side by side transfer for crew and resupply from a seismic support vessel.

    "Beyond this, the class notation also sets a requirement for the bridge arrangement to ensure good view to the streamers and any workboats that are close by during normal operation. High pressure systems are also addressed in the class notation to ensure that deck operations can be carried out safely by the crew."


     

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