An issue for many subsea oil and gas fields is that decreasing natural pressure is reducing recovery and shortening the lifetime of fields. Norwegian oil and gas multinational Statoil-owned Åsgard oilfield, situated about 200 km off the coast of Norway, has developed a process that could benefit the oil and gas industry for years to come.

Set for completion in 2015, the ground-breaking project will use subsea gas compression technology to maintain production and boost recovery from the Midgard and Mikkel reservoirs by the equivalent of about 278-million barrels of oil.

Statoil states on its website: “With Åsgard subsea gas compression, we are one step closer to realising our vision of a subsea factory. Subsea processing, and gas compression, in particular, are important technology advances to develop fields in deep waters and harsh environments.”

While this project represents a leap in seabed technology, the challenging applications will increase the demands on the equipment used. Apart from being water-resistant, the equipment must withstand the temperatures and hydrostatic pressures in deep-sea beds.

At these depths, fluids become warmer, resulting in a significant temperature difference, compared with the surrounding seawater. This can cause piping wax build-up and eventually clogging, potentially leading to costly production downtime and repairs.

Sophisticated thermal insulation is crucial to ensure a steady fluid flow.

With this in mind, Norwegian oil services company Aker Solutions – contractor of the Åsgard subsea compression system – will apply industrial group Trelleborg’s high-performance Vikotherm R2 subsea insulation to 600 m of piping. A well-proven solution, the material can easily be adapted to the varying geometries, surfaces and applications of the installation.

The rubber-based composite Vikotherm R2 system insulates and protects jumpers, manifolds, risers, pipelines, flow lines, equipment and other subsea structures. Maintenance-free, the product is designed to last the installation’s lifetime, a minimum of 30 years, so it will never normally require replacement.

“Vikotherm R2 is practically incompressible and both seawater and impact resistant. It effectively withstands both low and high temperatures and provides corrosion and mechanical protection. Competing systems may have the same individual properties but are unable to offer all of them as one package,” says Norway-based Trelleborg offshore and construction facility subsea sales manager Oddvar Kopstad.

Vikotherm R2 is made up of three layers, all bonded to one another. The inner layer is chemically bonded to the structure surface, ensuring protection against corrosion, hydrogen-induced stress cracking and disbondment. The middle layer provides thermal insulation, and the outer layer protects against mechanical and water ingress.
“The layer thicknesses and properties are extremely flexible, making it easy to adjust to environmental challenges and customer requirements,” Kopstad explains.

Launched in 2012, the Vikotherm R insulation builds on the success of its former generation, first manufactured in the late 1980s. The updated material has been subjected to years of rigorous testing, including lifetime evaluations, long-term simulated service tests and full-scale qualification tests. A notable upgrade to Vikotherm R2 is that it can be applied either on site or at Trelleborg’s production facility in Norway. “The growing global subsea market increasingly focuses on flexibility, delivery time and quality. So, it is a huge advantage to be able to apply it on site, anywhere in the world,” says Kopstad.

Application at the plant involves high-pressure and high-temperature vulcanisation, typically above 140 ºC, in an autoclave. Field vulcanisation is done at ambient pressure without an autoclave, but it retains the same properties.

With a market share of 20% to 25% and advanced growth plans, the future looks bright for Vikotherm R2. “In 2013, Trelleborg saw a significant increase in the specification of this solution and the company expects to see more growth, much of it as a direct result of Vikotherm R2’s on-site possibilities,” Kopstad concludes.