New cooling system raises efficiency of oil and gas processing

Using their expertise in fluid mechanics they have developed a unique design for a subsea cooling system. Their research can help to recover more oil and gas resources both in the North Sea and elsewhere.

More and more, the recovery and processing of Norwegian oil and gas is being carried out using equipment on the seabed. Mathematicians at the University of Oslo have devised a solution for making these processes more efficient at substantially lower cost.

The prizewinning solution may turn oil and gas fields currently considered unprofitable into money-makers.

Processing requires cooling systems

Much of today's petroleum recovery is conducted on the ocean floor, where in the future the process of separating out water and sand will increasingly take place as well.

Structures installed on the seabed can currently weigh thousands of tonnes, and will grow even heavier when equipment for subsea processing is added. One reason for this is that a cooling system will be required to cool the oil and gas from as hot as 150°C down to roughly 20°C before the separation process can begin.

Know-how in fluid mechanics

With expertise in fluid mechanics, researchers at the University of Oslo's Department of Mathematics have developed a unique design for such a cooling system. Fluid mechanics is a branch of physics that uses mathematical tools to study the movements of fluids and gases.

"Norway has a long tradition of calculating fluid flow, particularly here at the University of Oslo," says Professor Atle Jensen. Together with doctoral research fellow Stig Grafsrønningen among others, the professor has been studying the physics of cooling down liquids at seabed level. The team has found brand-new solutions to some of the petroleum industry's challenges.

This work is part of Mr Grafsrønningen's doctoral research at the University of Oslo (UiO), which receives funding under the Research Council of Norway's Large-scale Programme on Optimal Management of Norwegian Petroleum Resources (PETROMAKS).

"We now know the optimal design for the cooling equipment," says Mr Grafsrønningen, "and our laboratory tests of it have been very successful."

Mathematics for innovation

For their Heat Exchanger project, the researchers recently won a respected innovation award from the company Inven2, Norway's largest player in commercialisation of research. Inven2 is owned by UiO and Oslo University Hospital, and cooperates with the Research Council's Programme on Commercialising R&D Results (FORNY2020).

"It is terrific that a group of mathematicians can win a prize for innovation in industrial development," says Ivar Bergland, Project Manager at Inven2.

"This is research that can help to recover more oil and gas resources in the North Sea and elsewhere. The project is further proof of how important the theoretical disciplines such as mathematics and physics often prove to be for advanced industrial activities."

Lasting solutions

Marine cranes are limited in the size and weight of the structures they can lift, so it is vital to make a bulky subsea module such as a cooling system for oil and gas as small and lightweight as possible.

The first newly constructed processing facilities could be installed on the seabed as early as 2013. This equipment will be designed to last 30 years, which means that in addition to being smaller and lighter, it has to be durable, maintenance-free and without moving parts.

Natural gas pipelines next

An upcoming step in commercialising this patent-pending process will be to licence it out to major players in subsea petroleum recovery.

The researchers hope one day to see their optimised cooling process used in connection with the export of Norwegian oil and gas to the Continent via subsea pipelines. Extremely long pipelines made of stainless steel would be cost-prohibitive, but the alternative -- less costly carbon steel -- rusts more quickly if the oil and gas being transported is too warm. This is where the UiO team's cooling system could prove quite useful.