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Oilfield Technology
May
2015
This demand for data is putting pressure on ship‑owners to
provide dependable communication and connectivity networks on
board offshore vessels. If the success or efficiency of an operation
depends on the ability to share and act on the data it generates, loss
of connectivity on board is unacceptable. Connectivity dropouts are
not just a case of losing the ability to send a few emails. Without an
IP connection, contact with remote experts supporting an operation
becomes impossible. The ability to monitor, visualise and act on
well sensor data is lost. Seismic surveys lose the ability to act on
and adapt dynamically according to what they find. Even fulfilling
regulatory requirements becomes a (potentially) costly challenge
without access to the company LAN. This all eats away at the bottom
line.
For clients that depend on data, a ship‑owner has to offer
guaranteed availability of connectivity, usually in the form of a
Service Level Agreement. The better the SLA, the more confident a
client can be in the level of investment that the ship‑owner has made
to protect the integrity of its on board networks and satellite services.
The most common way of losing connectivity in offshore operations is
through antenna blockage, where line of sight to the satellite is lost.
The cost of losing connectivity to a client can be high, so by investing
in the best, most reliable technology and services, the ship‑owner is
reducing a client’s financial risk. A single VSAT antenna provides high
levels of reliability but there is a growing trend for vessels in the E&P
sector to add a second, so when the first is suffering from blockage,
the second can take over. This is done in two different configurations.
Two VSAT antennas connected to a single router/switch so if one
cannot connect to a satellite, the other will. Or, for the very high‑end
SLA, a fully redundant solution, with literally two of everything, down
to the wiring on board. This approach also takes into account single
equipment failure as well as blockage, as there will always be a
complete back‑up system ready to take over if something fails.
Though using a single standardised VSAT antenna may be perfect
for merchant vessels, some offshore vessels involved in critical work
that relies on intelligent operations for greater safety and efficiency
may opt to secure connectivity even further. Regardless of how a
vessel doubles‑up to improve satcom service availability, the network
design, service and technology choice, installation and operation
is a complex task. But the ship‑owner is an expert in ships. Not IP
connectivity. So ultimately, the pressure to provide reliable, high
bandwidth communication falls to the satcom service provider, who
is the expert.
Dual antennas
At present, the seismic survey sector perhaps most reflects the
high‑end of offshore satcom connectivity with users requiring
significant SLAs to ensure they have the best available connectivity.
Seismic operations require a highly skilled crew to be on board.
However, should any technical difficulties arise, for example with
the vessel engines, having the provision for remote diagnosis via
Internet through satellite can negate the need for costly call‑outs and
transportation from on‑shore including the related high fuel usage.
For one particular seismic vessel operator, the installation of
Marlink’s Sealink™ C‑band VSAT service on board its purpose‑built,
3D seismic vessels was always a priority as it is designed to ensure
the specialised fleet can meet the demands of offshore seismic
exploration on a global scale. Customised to meet the technologically
advanced requirements of this fleet in terms of reliability, the
Sealink VSAT system includes two C‑band antennas with automatic
switchover and dedicated full‑duplex bandwidth. The dual system
also includes several LAN networks on board, eight simultaneous
voice lines and access to Marlink’s advanced prepaid platform.
The dual antenna systems means that when a vessel is carrying
out a seismic survey, conducting survey lines back and forth,
an antenna will always have a clear view to the satellite. This is
important as especially when operating in low elevation areas, like
the Barents Sea with as low as 0 ‑ 5˚ elevation, structures on board
Figure 1.
A field engineer examines satellite communications
equipment.
Figure 2.
The dual redundant network approach.
