Interview: Thirty years of development of subsea wet gas compressor

In anticipation of Offshore Energy Exhibition and Conference 2015 (OEEC), taking place in Amsterdam next week, Offshore Energy Today had an interview with Mr. Arne Birger Olsen, Director Sales – ECR at OneSubsea, a company that provides integrated solutions, products, systems and services for the subsea oil and gas market.

Olsen will be one of the speakers at the Subsea Processing session that will discuss the latest developments in subsea processing solutions.

In our interview, we talked about OneSubsea’s latest technology development, the world’s first subsea wet gas compression system, and its importance for the industry.

OET: OneSubsea developed the subsea wet gas compression system in collaboration with Shell and Statoil and the first commercial OneSubsea wet gas compressor was installed on the seabed and then tied back to Statoil’s Gullfaks C platform in the North Sea in July. Can you briefly explain its function?

Olsen: The technology is capable of reducing the back pressure on the gas wells and overcome losses through the pipelines, and hence allows the gas to flow more easily to the process facility, it being platform or land based.

…can boost any combination of liquid and gas without separating the two phases.

OET: With the compressor now in its place, when is the production scheduled to start and what will its start-up mean for the Gullfaks field?

Olsen: The production is scheduled to start later this year and, according to Statoil, it will ultimately increase the recovery rate from the field from 62% to 74%.

OET: OneSubsea won the Spotlight on New Technology Award at the Offshore Technology Conference in Houston for its multiphase compressor. What was the main driver behind the development, how long did it take to develop, and what is its importance of such technology?

Olsen: OneSubsea (or legacy Framo Engineering) started developing the wet gas compressor technology in the late 1980s driven by the request for boosting of large hydrocarbon volumes and in particular gas. However, the market was not really ready for this when the technology became mature enough to be utilised and it has taken nearly 30 years until commercial success.

The real importance is tied to the fact that this technology, as the only one available, can boost any combination of liquid and gas without separating the two phases.

The other great benefit with the OneSubsea wet gas compression technology is related to a phenomenon typically experienced with other compressors technologies called surge, which can lead to a machine running into self-destruction. This is challenging to control topside, let alone subsea. Our technology is not exposed to such issues which is something that makes subsea operation a lot less complex.

…the closer you get to the wells, the better recovery rates you achieve. 

OET: What was the biggest challenge during the development?

Olsen: Our main focus during nearly 30  years of development and improvements has been to increase the capacity of the machine to match the market needs.

OET: Are there any other operators interested in this solution? What are their main concerns?

Olsen: There are, as usual, quite a few candidates who want to be second in line after a successful operation at Gullfaks is confirmed. Concerns are similar and related to how subsea compression technology can be commercially attractive for their fields.

OET: As subsea processing provides an alternative to the equipment located on a fixed or floating platform, can you tell us what are its advantages over topside compression? In fact, why was it moved to the seabed?

Olsen: The advantage lies in the fact that the closer you get to the wells, the better recovery rates you achieve. There are also issues related to manning of platforms with associated Opex cost and safety issues.

OET: In what way is subsea compression a game changer for the industry?

Olsen: It allows tying back large gas fields to existing infrastructure or to beach in an economical way as well as increasing the recoverables.

OET: Can you tell us more about various scenarios when it comes to the deployment of your subsea compressor? In what depth, what kinds of fields, and in what parts of the world can it be used?

Olsen: The technology is qualified for design pressures of up to 5000 psi and for water depth to 2000 m. With the current design we are able to boost fairly large subsea gas fields with limited number of compressor units.

OneSubsea is working to increase the capacity even further to allow this technology to be effective also for the largest gas fields.

OET: The oil companies have vowed to try and tackle climate change. How can subsea compression help with that?

Olsen: By avoiding or minimising topside installations with personnel which requires transportation to and from by helicopters. Gas has the potential of replacing other sources of electric power generation which can be much more harmful to environment.

OET: You will be one of the speakers at the Subsea Processing technical session during Offshore Energy Exhibition and Conference 2015 in Amsterdam next week. What do you hope to bring to the conference?

Olsen: I want to ensure that our compression and boosting technology becomes more known to the industry in general and to stimulate the oil & gas community to consider this technology for future developments.

Offshore Energy Today Staff