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Developments in subsea digital technology

Thursday, July 3, 2014

The subsea digital technology arena is seeing improvements in control, public communications, subsea wireless, ROV operations, sonar, acoustic communications, video management and modelling - highlights from Aberdeen's Subsea Expo in February

Aker Solutions - first subsea compression

Aker Solutions is building the world's first subsea gas compression unit, for the Asgard field in Norway, to be installed in 2015, following 3 years of testing. The template (metal frame around it) is half the size of a football field, said Matt Corbin, UK Managing Director for Aker Subsea.

The idea for this was first mooted in 1985, so it has been a 30 year development project.

There are a lot of interesting subsea projects going on in the North Sea, including BP's 'Quad 204' project West of Shetland, Chevron's Rosebank Northwest of Shetland (currently on hold), BP's Clair oilfield West of Shetland, Total's Laggan-Tormore project North West of Shetland, Premier Oil's Catcher project, and the EnQuest Kraken project, Mr Corbin said.

Aker Subsea grew out of the subsea division of a UK electronic engineering company called Ferranti International Plc, called Ferranti Subsea Systems Limited (FSSL) after a 1990 management buyout. It received investment from Norwegian construction company Kvaerner in 1994 and was renamed Kvaerner FSSL; then became a subsidiary of Aker ASA called Aker Kvaerner, and finally named Aker Solutions.

FSSL built the first subsea control system in the late 1990s, with a topside control unit based on a Sinclair ZX81 computer. 'Some are still working today,' he said.

Last year (2013) Aker Solutions started offering full lifecycle management services for its equipment. It employs 3,000 people in the UK. Products include subsea pumps, separators, trees, instrumentation and controls.

Around the world, Aker Solutions is seeing a growing problem meeting 'local content' requirements, when countries say that a certain amount of work has to be supplied locally, to protect local employment, he said.

'We can resist and push back and say 'no that can't be done in country', or we can lead the in country developments - so the heart of it comes from the UK subsea supply chain,' he said. 'You either drive it or get driven by it.'

A current problem in Aberdeen is the spiralling wages and skill shortages, he said. 'We continue to do ourselves an injustice by poaching staff and inflating wages. The only winner is recruitment consultants. Poaching staff hurts every one of us.'

Mr Corbin does not believe in blaming universities for not providing enough competent engineers. 'I don't necessarily believe it is just universities' responsibility to prove ready-made employees. I'm just as interested in people with aviation or automotive background as well as oil and gas. Getting the industry into their hearts and minds is the key.'

WFS - Integrated Subsea Wireless Solutions

WFS Wireless for Subsea has technology which allows wireless high speed transmission of data in subsea deep waters over short distances, avoiding the need of installing 'wet mate' connections which are complex and very often prone to failure. The company counts more than 5,000 wireless subsea systems installed around the world to date.

A key subsea application is monitoring the condition of a cathodic protection system. Cathodic protection (CP) is a technique used to control the corrosion of metal by making it the cathode of an electrochemical cell. In passive CP, protection comes from a "sacrificial' metal attached to the corrodible metal, to act as the anode. As long as the CP system is maintained, a complete absence of corrosion is guaranteed.
In subsea applications, a 850 to 950mW potential current typically arises between the anode and cathode. The anode's life cycle is between 10-20 years, during which the potential current starts to decline. It is important to identify the exact point when the degradation starts, and the rate of degradation.

'A common practice in measuring potential currents is the use of probes mounted on Remoted Operated Vehicle (ROV) every two-three years', says company founder and chairman Brendan Hyland.

WFS provides an alternative solution, Seatooth CP, a subsea wireless datalogger that monitors the effects of corrosion by measuring anode current and transmitting data wirelessly using a Seatooth S100 device to a wirelessly enabled ROV.

This data is periodically harvested wirelessly by ROVs or divers providing the maintenance team with time-stamped data and continuous charts showing the condition of the CP system for both preventive and diagnostic applications. This is an easy and cost effective solution that provides data continuously throughout the period that the datalogger is deployed on the anode allowing detailed trend analysis.

The same wireless technology is used for Seatooth PipeLogger, for monitoring pipeline integrity. It is a pipe-mounted sensor that measures temperature data at the pipe surface under a thermal insulating 'skirt' to ensure core pipe temperature. Other sensors (e.g. pressure, flow UT, vibration) can be added to support asset integrity management.

WFS has also developed wireless subsea cameras that can transmit video and images at 10 frames per second, at a data rate of 78-156 kbps. During complex ROV operations, providing live videos of the ongoing projects is very important to ensure the project is completed safely and efficiently. For similar activities, the use of a second ROV providing video cameras used to be necessary - but now a wireless subsea camera is available to be used at any time in depths up to 4000m.

The systems have been deployed in many corners of the world including South East Asia, North Sea, Gulf of Mexico and Australia.

SeeByte - make ROVs easier to operate

SeeByte, a company based in Edinburgh which makes software for underwater vehicles, has been making advances with making ROVs easier to drive, and to act more autonomously.

Its software allows a ROV to be connected with a mouse, rather than a joystick.

The software enables the operator to maintain much more control over the vehicle, whilst making it easier to control.

If there are many other objects in the subsea region, the software can automatically guide the ROV around them.

One customer is ROV manufacturer SMD, who say that the software 'is one of their main selling points', Ms Irvine says.

The software is used on both large 'work class' ROVs and micro ROVs which can be carried by one person.

CodaOctopus

CodaOctopus of Edinburgh, a company which provides subsea surveying equipment, has developed a new 3D sonar for use on ROVs, which is designed to be much easier to operate.

The company has 2 sonars for ROVs - the previous one 'EchoScope' (launched in 2006) and the new one 'Dimension'.

'We know ROV pilots have got too much going on, they don't want to be playing with software,' says sales manager Gareth Simpson.

The sonar can provide a 3D picture of what is in front of the vehicle - and because the image is generated by sonar rather than video, it does not matter if there is no visibility.

Using just one sonar, the system can compute what the obstacle in front of the ROV would look like if viewed from above, as well as the view which the ROV has facing forward.

The Dimension has beams spread at over 90 per cent angle, to give a fairly wide view.

'ROV companies are looking for something which is simpler to drive,' Mr Simpson says.

Nautronix

Water communications company Nautronix has launched 'NASDive', a system for communications between technical divers and the diving bell, vessel and each other.

Speech communications between divers gets more difficult with depth, due to the increased helium content of the gas mixture they breathe, which is to compensate for the effects of high pressure. The helium in the air changes the voice sound produced from the mouth, so the voice is high pitched and difficult to interpret.

Analogue voice communication systems are also subject to noise interference from other electrical systems.

The NASDive system is fully digital. It includes a 'helium speech unscrambler' which transforms divers' high pitched voices back to their normal voice.

The data is sent digitally, to avoid problems with sound interference.
The system can be controlled remotely from an iPad or other tablet device.

Nautronix is also developing its wireless communication technology to provide better ways to reduce noise, says Lindsay MacDonald, director of technology.

Cortez Subsea

Aberdeen subsea engineering company Cortez Subsea is delivering a new software platform to the UK market for managing asset inspections and the associated video to help operators keep track of subsea pipelines and platforms.

Pipeline Commander and Structure Commander software systems can be used for managing the inspection and monitoring of subsea pipelines and underwater assets.

The majority of the data processing can be completed onshore via the unique Offshore Automated System, rather than having to send people out on vessels.
Cortez Subsea is selling an inspection service using the software, and the core team of data processors and offshore dedicated inspection team.
Using GIS technology, the video can be indexed geographically, so you can easily pull up a video image of the pipeline at a certain point.
The idea is to make it much faster to generate a report of the condition of the pipeline overall, and plan what work needs to be done on it.

Altair - faster simulation

UK engineering consultancy Altair has developed computer modelling and simulation tools designed to 'lighten' the computing load, so you can use it for simulation.

By using the same software for design and simulation, you can review the full impact of changes you can make, what the trade-offs are, and try to come up with a better end design.

So for example with an FPSO, there are various styles of vessel design you can use, and the design has an impact on buoyancy. There is no obvious way to do it.

With the computer software, the trick is to work out 'how much detail you can cut away to make an efficient model which lets you do some design simulation,' says Gareth Lee, applications engineer with Altair Engineering. But also, you can get more computing speed with more computing processors, or 'cores'. "Roughly speaking, if you double the number of computer processing cores, you can double the speed of the simulation modelling," he says.

With a system like this, you can work which are the most critical settings you need to optimise to get the best overall result.

You can use the system to get a model of how fluids interact with the structure in a complex way. For example, as fluids flow up a riser, which is also subject to water currents around it, and has a buoyancy system keeping the riser in a 'U' shape.

You can model how something would be damaged by a collision with a ROV.

Altogether, you can make designs which are much more reliable.



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