Page 67: of Offshore Engineer Magazine (May/Jun 2013)

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Production

Norway, where the technology has array where sensors are desired.

seen most deployment, there will PGS will acquire seismic data once probably be a dozen 4D seismic a year using a source vessel and pas- surveys, mainly undertaken by the sive seismic data twice a year. It will better-resourced oil companies. process the seismic data at its center

Worldwide, the technology is only in Rio de Janeiro. Early results are gradually being adopted, and for said to be promising. many companies the value is too Before the Fugro-CGG Seabed So-

A node with optical wet-mates enables intangible to justify the risk and lutions joint venture was initialled in the connection to the array loops. expense for stakeholders. They may February, CGG had conducted four

Riser cables from the FPSO and other also not have the technical resources monitor surveys on the Ekofsk feld lead-in cables help position the array to adequately deal with the data pro- in 70m water depth. Its OptoWave where sensors are desired.

vided. It’s also true that the case for fber-optic system was installed for 4D seismic does not always exist for is said to be more reliable and long ConocoPhillips, covering an area simple geological reasons, or scale, lasting, principally because no in- of 60sq km with 200km of cable i.e., there are not enough reserves to sea electronics were involved and trenched at one-meter depth, con- work with. fber-optic cable has a long-term taining 4000 four-component receiv-

Since the Valhall LoFS installa- track record in the transocean com- ers. That service has now devolved tion, the service sector has basically munications business. to the joint venture. had to engage in a battle of persua- The response to the fber-optic Whatever the merits of the fber- sion with the oil companies over option has been mixed as far as optic solution, Geospace Technolo- seismic PRM on two fronts, technical take-up is concerned. On the Petro- gies has stayed in the game with its and cost. It has already been a long bras Jubarte feld off Brazil, PGS has conventional ocean-bottom cable ap- campaign with no obvious outcome. recently completed the deployment proach. Last year, it won a $14.9 mil-

A number of companies believed of what is said to be world’s frst full- lion contract to provide over 100km that they could improve on the bur- solution, deep water, seismic PRM of deepwater seabed seismic reser- ied seabed cable program adopted installation in water depths between voir monitoring equipment for the for Valhall, using the pioneering 1200m and 1350m. BC-10 feld off the coast of Brazil, op- equipment supplied by OYO Geo- The project makes use of OptoSeis, erated by Shell. The system will be space (renamed Geospace Technolo- a fully fber-optic sensor array in- laid on the sea foor in 1700m water gies last November) that’s based on stalled on the seabed with opto-elec- depth. The company followed this conventional, ocean bottom cable. tronics on the topside of the FPSO up later in the year through Statoil

Their goal was to answer the per- P-57. The sensor array cables are contracts worth $160 million for ceived industry concern over the laid out in two loops on the seabed 660km of seabed seismic reservoir longevity of the systems designed to with array cables placed 300m apart. monitoring systems at the Snorre and last 25 years. Three solutions, Op- There are sensor stations every 50m Grane felds on the Norwegian con- toWave (now part of the Fugro-CGG along the cables. tinental shelf. Separately last month,

Seabed Solutions joint venture), A node with optical wet-mates CGG announced it had received the

OptoSeis (now part of PGS), and enables the connection to the array contract for long-term seismic imag-

Stingray (now part of TGS) offered loops. Riser cables from the FPSO and ing services for the project.

a fber-optic based alternative. This other lead-in cables help position the The choices of seismic PRM sys- oedigital.com May 2013 | OE 69

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