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Surveying the Baltic Sea for Nord Stream 2
Offshore surveyor iSurvey recently completed a 40km seabed study in the German Baltic Sea as part of the international Nord Stream 2 pipeline project. Heidi Vella spoke to the company’s business development manager, Grant Aitchison, to discuss the logistics
Credit: Nord Stream 2 / Paul Langrock
he Nord Stream 2 pipeline is an ambitious project to transport natural gas from the world’s largest reserves in Russia to the European Union internal market.
When finished, it will have the capacity to transport 55 billion cubic metres (bcm) of natural gas per year through a 230km pipeline that starts on the Russian coast, travels through the Baltic Sea, and hits landfall in Germany. Over 200km has been laid to date. The expansive project requires a high level of engineering skills and various collaborations between different contractors.
In June 2018, Allseas Group, a contracted pipe-layer for the project, hired Norway-headquartered iSurvey to complete a geophysical survey of 40km of the German Baltic seabed prior to pipelaying.
The seabed survey was conducted aboard a SeaZip FIX charter due to environmental rules that prevented Allseas from using its normal pipeline vessel, which relies on thrusters to move the vessel along, risking creating environmental damage.
Instead, the company needed to use anchors. However, before work could start, iSurvey had to map the seabed floor to determine if there were any major obstructions or hazards.
Mitigating risk: detecting seabed obstructions
“Allseas needed to know if, over a several kilometre-wide corridor, it was possible to place its vessel anchors safely on the seabed floor to form the pipeline, then lift them up, move along, and repeat for weeks on end until the pipe was laid over the entire section,” explains iSurvey business development manager, Grant Aitchison.
The work needed to be done as a distinct separate operation in case something was discovered on the seabed floor that might force Allseas to re-engineer the pipe routes around the obstacle or to alter its anchoring pattern.
“They needed to confidently start laying the pipe without having to unexpectedly change its route direction or curvature, which would have cost them a great deal of time and money,” explains Aitchison.
To conduct the survey, the company used what Aitchison calls “well proven industry, standard geo-physical survey sensors,” such as a combined multi-beam echo sounder (MBES) and side scan sonar (SSS) systems mounted on the hull of the vessel and towed by a couple of magnetometers and a gradiometer, so they could detect any metallic objects or items on the seabed.
“We also had other associated positioning and altitude monitoring systems to make sure it was possible to marry the data collected from one day to the next, to form a nice integrated data set,” explains Aitchison.
The company also used a remotely operated vehicle (ROV) for greater inspection of any targets picked up on the site scan or magnetometer.
Facing new challenges: delivering a complete turnkey service
For iSurvey, which was founded in 2004, the main challenge, says Aitchison, was charting the boat and delivering a complete turnkey service for the vessel, survey, ROV and porting – something the company had never done before.
“Most of our operations typically involve people and equipment on client vessels or assets, but this time we were responsible for everything,” says Aitchison. “It was a challenge for our organisation as a whole, we had to piece it all together and get everybody working as a team.”
The company recruited geo-physicists and an ROV crew, which had to work with the main crew, survey crew and the client’s crew. Together the combined team of 10 spent over 30 days on the project.
“There was all this rapid team building; we needed to get up and running and working efficiently as quickly as possible and we managed to do that pretty well,” says Aitchison, who has worked for over 30 years in the oil and gas industry in various positions from offshore surveyor to project management and senior management roles.
Meeting demands through careful preparation
To meet the demands of the new working model, the company used “every minute” of its time after winning the contract to prepare for the project. It tested systems in the workshop that were going to be on the vessel, integrated them altogether, including all the acquisition and processing software, so those working on the job could see how everything was going to gel together beforehand.
“Nobody had used all of the equipment before, so there was some learning required before we started to make sure we knew what we were doing – you can sometimes underestimate the value of good preparation and pre-mobilisation,” says Aitchison.
“But doing this definitely reduced our commercial and operational risk and meant we saved time when we got to the boat and started putting things together, because we already knew what we were doing,” he adds.
Other challenges included managing the sensors in the shallow seabed. Most of the route was in less than 20m water depth, which made it particularly challenging to handle the sensors adeptly so they didn’t crash into each other all the time.
“There was a particular way the weather and currents worked and the vessel behaved in that area of the Baltic Sea that meant we needed to learn and adapt and work out how everything was going to behave and respond to make sure it didn’t slow the execution of the work scope,” Aitchison explains.
Future projects in the pipeline
The company completed the survey on time – it took just over a month – and on budget, and is now keen to take on new opportunities offering turnkey solutions for other, similar projects. It is not working again on Nord Stream 2, however.
Aitchison says there's likely just as many or even more opportunities for the company to repeat this type of survey in the renewable energy sector, as well as in offshore oil and gas. The firm, which he says doesn’t strive to be the cheapest but to offer the highest quality services, also plans to grow its workforce and footprint for such future projects.
“We’re talking with the companies we worked for this year to get an idea of their expectations and what their demands and project requirements are moving forward, then we’re looking at balancing that against our resources to see what other opportunities there are for us with new clients,” he says.
“So, we’re actively tendering on a number of projects presently, across renewables predominantly, but also for oil and gas projects in the North Sea – and internationally.”
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