Page 63: of Offshore Engineer Magazine (Apr/May 2014)

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WFS Technologies recently delivered

Freespace optics repeaters (transceivers/relays) to transfer Mb/s bandwidth at ranges up to 200m.

Subsea wireless communication systems

Free-space optical (FSO) communica- data to and from life of ? eld AUVs, or The system could be combined with to Baker Hughes for a pipeline pre- tion offers the greatest potential for high along a network of links, spaced 0.5km underwater acoustic communication commissioning project. data-rate communication, including HD apart, to send a signal. technology to provide more modest band-

The ? rm’s Seatooth S100 system video in real time subsea, but it also Signi? cant research and testing has widths over longer ranges.

was used for wireless data logging poses challenges and there have been few been carried out in this ? eld, however, to BlueComm has been demonstrated in during pipeline pre-commissioning commercial applications to date. date, there are few commercial systems a 2010 project, in which it was used to on a project in the South China Sea,

FSO can have a higher data rate than available. control an ROV that was installing equip- in 1000m water depth. The data any other approach because its beam Woods Hole Oceanographic Institute ment on the seabed at the Juan de Fuca transfer rate was 2.4kbps over 5m is more collimated (light whose rays engineers recently developed and pat- Ridge in the Paci? c Ocean. range through seawater (the system are parallel, and therefore will spread ented a free-space, underwater optical Woods Hole has been working with can operate at up to 4.8kbps up to 5m minimally as it propagates) and its short communications system using light to UK-based subsea communications ? rm through water). waves (higher frequencies) can carry transmit data through water. Sonardyne International, to get the tech-

The transmitter included a Seatooth more data. The system, BlueComm, provides 1 nology ready for the marketplace.

S100 connected to a hydro-test skid.

It uses modest antenna size of about

The receiver comprised a Seatooth 10cm, with modest power consumption.

S100 mounted on the remotely operated

It suffers less from interference from vehicle (ROV), but key was its lower electromagnetic ? elds, acoustics, and, in power use, relying only on batteries. deep-water, background sunlight.

Both units were bidirectional and no

But, subsea FSO is challenged by high con? guration was required; the system extinction and the immense variabil- was ready to plug in and deliver serial ity in the optical properties of ocean communications wirelessly between the test skid and ROV. Hydrotest data waters. was downloaded at high speed, despite

FSO uses visible light, in the blue- the high levels of salinity and turbidity. green region of the visible light spectrum, between blue and green on the electro- due to advanced digital signal processing magnetic spectrum, to communicate and signal compression techniques.

underwater wirelessly. This is because

RF can transmit with greater band seawater is light absorptive, except widths, more quickly than acoustics, is around a 400-500nm (nanometer) wave-

InnOVaTIVe able to cross the water to air boundary, length window—the blue-green region of as well as through solid objects, such as the visible light spectrum. pipe walls or ice. However, due to signal Blue-green light is therefore able to subsea attenuation (degradation) through water, be transmitted as a continuous wave or its range is limited. pulsed wave, using semi-conductor light

RF has been used in the oil and gas emitting diodes (LED) and laser light

InsTallaTIOns industry since the 2000s. In 2006, WFS sources, and detected using highly sensi- launched it’s the Seatooth S1510 Medium tive, PIN, APD (avalanche photodiode), range communications system, which is or single photon detectors.

Revolutionizing conductor

InterMoor’s team applied out-of- able to transmit signals of up to 16kbps With today’s technology, FSO range is the-box thinking to design, procure, over 20m in seawater, and the Seatooth limited to less than 1km at high data- installations in deepwater.

fabricate and install conductors

S5510, able to transfer 1-10Mbps up to rates (sub- Mb/s), due to beam scattering off the rig’s critical paths for two 1m through water. and beam absorption in water. major international oil and gas

Successful trials using an HD camera Ocean water also has widely varying companies in Brasil’s southern clamped to an asset with a 3-6m range optical properties, depending on loca-

Campos and Espirito Santo Basins. to give multiple viewing angles during tion, time of day, organic and inorganic

The InterMoor-driven solutions of a subsea construction operations have content, as well as temporal variations, dedicated barge for launching the been run by WFS with Technip, Canyon, such as turbulence and surface motion.

conductors, combined with sister

Fugro, and Subsea 7. Irradiance levels, even in clear water company MENCK’s subsea hydraulic

In the North Sea, a new generation of at 0.5 - 1 km distances, are comparable to hammer deployed from an AHV, pipeline/? owline ? ow assurance solu- those predicted for interplanetary laser at water depths up to 1,900 m / tions radio-enabled subsea instruments is communications.

Mooring • Foundations • Subsea 6,300 ft. proves InterMoor is at the being deployed. FSO can also suffer from inter-symbol forefront of foundations installation.

This could be used to monitor interference (ISI), a form of distortion of [email protected] That’s Foundations Expertise. pressure and or hydrate build-up, for a signal, in which one symbol interferes example, building on existing inter- with subsequent symbols, which has a www.intermoor.com/foundations Operational Know-How. nal pipeline inspection using pipeline similar effect as noise, and the transmit inspection gauges. This would utilize signal can be dispersed, due to power

Visit booth #555 · OTC · May 5-8 wireless communications through the scattered in water.

ANgOlA – BrAzIl – EgypT – EquATOrIAl guINEA – MAlAySIA – MExICO – NIgErIA – NOrwAy – SINgApOrE – uK – uSA pipe wall, using modems on the PIG To circumvent some of the limitations and ROV to receive the data, across the of free-space optics, optical link concepts higher bandwidth. have been proposed, using underwater oedigital.com April 2014 | OE 65 000_OE0414_Subsea1_wireless.indd 65 3/22/14 9:21 PM