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Jansz-Io on radar for subsea compression

Chevron-operated development off Australia could be first outside Norway to host technology

Aker Solutions has reached an agreement with US supermajor Chevron that could see the Norwegian company’s pioneering subsea compression technology put to work at the Jansz-Io field off Australia.

The companies have signed a master contract to support delivery of the subsea compression system with the first service order under the agreement to include front-end engineering and design of the system, along with FEED for an unmanned power and control floating platform.

The agreement lays the groundwork for a potential engineering, procurement and construction contract that would make the project the first use of the subsea compression technology outside Norway.

Aker launched the first system in September 2015 at Equinor’s Aasgard field.

A subsea compression system for wet gas delivered by OneSubsea came online at Equinor’s Gullfaks South field a month later.

Knut Nyborg, head of front-end at Aker Solutions, says the agreement is a vote of confidence in the nascent technology.

“It is definitely an endorsement of the technology itself and the track record at Aasgard, as well as the team that delivered Aasgard and the facilities that were used to deliver it,” he says.

The Aasgard unit “has been working fine now for three-and-a-half years”, he adds.

Recovery rates

The company says that, by placing the compression equipment on the seabed near the wellheads, the technology improves recovery rates compared with traditional systems mounted on platforms.

Advocates say the technology, along with other subsea production systems, can also lower development and operating costs while reducing a project’s carbon footprint. The system is part of a suite of technologies, some still in development, designed to move more oil and gas production, processing, power, inspection and storage capabilities to the seabed — what early on was being touted as the subsea factory.

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Nyborg says that, in the current cost-containment and lower-emission climate, discussions now revolve around what combination of subsea technologies are best suited to a project and its operator.

“What we have come to realise is that, yes, there are a lot of technologies out there, but everything comes down to what is best for a specific field,” he says. “There are some fields that require compression when the pressure has declined, and other fields that may require taking out (carbon dioxide) and reinjecting it.”

The Jansz-Io field, part of the Chevron-operated Gorgon development, is about 200 kilometres off the north-west coast of Western Australia in water depths of around 1350 metres.

Greater depths

Production from the field runs to the Gorgon liquefied natural gas facility on Barrow Island via a 130-kilometre subsea pipeline.

The system installed at Aasgard is in comparatively shallow water depths of 345 metres but most of the equipment was qualified to greater depths, Nyborg says.

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As the Aasgard system was getting up and running, Aker Solutions and project partners MAN Energy Solutions began working to bring down both the size and cost of the compressor module, with the aim to reduce the weight and size of future systems by half without compromising the functionality of the Aasgard system. The modules that compose Aasgard’s twin trains, each driven by a MAN Energy Solutions 11.5 megawatt HOFIM compressor unit, are housed in a template structure 20 metres tall with a footprint of 75 metres by 45 metres and a total weight of about 4800 tonnes.

Nyborg said at the time that the size was necessary to meet the operator’s schedule and to make sure the system functioned as planned.

Engineers designed a new configuration that fit all the compression system modules in a standard four-slot production template that could be installed without the need for a large heavy lift vessel.

The design reduced the number of modules per train from 13 to seven and greatly simplified the hydrate prevention system, optimised the process piping and cut the number of electrical jumpers from 155 to fewer than 50 for each train.

The Australian project will include many of the modifications, resulting in a simplified system that weighs much less without compromising functionality, Nyborg says.

“We have implemented quite a lot of those changes,” he says.

“Working with MAN, we have had really significant weight and size reduction on this compression module.”

Due to its significant volumes and flow rates, the Jansz-Io subsea compression project will require around three times higher compression duty compared to the Aasgard project.

“This will be really powerful stuff,” says Nyborg.

Subsea gas compression and other seabed technologies are a good fit for Australia, which recently surpassed Qatar to become the world’s top LNG exporter, Nyborg says.

“I think both the cost perspective and low carbon perspective would hopefully argue for some more of these subsea technologies in the future,” he says.

“Most of them are inherently lower carbon, have less power consumption and have less materials in them.”

The subsea factory, he says, “is not a goal in itself, as we see it, but means having the necessary tools to be able to develop a particular field in the most economical way and, more and more importantly, with the lowest carbon footprint.”

Chevron operates the Gorgon project with a 47.3% interest and is partnered by ExxonMobil and Shell, each on 25%, Osaka Gas on 1.25%, Tokyo Gas on 1% and Jera on 0.417%.

d92e0c319832923a87459c0b76276d7d Developments: Aker Solutions head of front-end Knut Nyborg Photo: AKER SOLUTIONS
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