Bergen, Norway 11 – 13 June, 2019

When the going gets tough – we go subsea

Most of the “easy oil” has already been found. Tomorrow’s oil and gas production will be at greater depths, in areas with a more complicated infrastructure and in a harsher environment. All this will present major new opportunities for subsea installations – which will go “longer, deeper, colder”.

– In the future, longer distances, harsher environments and deeper waters will favour subsea well developments as opposed to topside drilled and completed wells, says Tor Willgohs Knudsen, Project Manager Gullfaks Subsea Compression and Senior Advisor Subsea Technology Operations at Statoil and member of the board of Underwater Technology Foundation hosting the UTC conference.
At present, Statoil has just under 500 subsea wells on the Norwegian Continental Shelf. These account some 50 % of the total production. Every year, an average of 20 new Statoil wells are put into production.
– There is a worldwide trend towards greater use of subsea developments. This has created a pressing need for continuous improvements in well-system reliability and availability. Globally, over 70 % of the wells in deep water developments that are either in service or committed are subsea. This statistic demonstrates the industry’s reliance on these systems, says Knudsen.

25 years under water

Statoil started its development of subsea wells over 30 years ago. The company was a subsea pioneer, and still holds a leading position within this sector. Knudsen was among those central to the development, and was present when the first oil from a subsea well reached Gullfaks A around 3am on the 22nd of December 1986. Since then, the development of subsea technology has gone from strength to strength.
– We have an inner drive which has enabled us to challenge barriers and push the technology forwards. Hence, the boundaries have been moved all the time, says Knudsen.
The key challenges at Gullfaks were to develop subsea technology where the installation did not depend on diver assistance, large enough subsea valve trees (Christmas trees) and the development of multiphase technology for production from satellite fields that could be located far from the production platform.
– In 1982, Statoil came up with a vision of developing a diverless subsea technology that would work at Gullfaks as well as at future field developments in deeper waters and far from the shore. Hence, we had also to develop technology for multiphase transport over long distances, says Knudsen.

Subsea factories

Since then, the technology has moved forward in quantum leaps, and solutions such as subsea separation, boosting and compression are achievements that can be credited to Statoil’s drive and strong cooperation with researchers, partners and suppliers. Subsea separation is an example of technology that had not seen the light of day until Statoil had the courage to introduce a full-scale implementation at the Tordis field following a previous pilot project at Troll.

The company are now developing the first subsea compression technology to be used on Åsgard, Gullfaks and other fields. It is planned for the technology to be realised in 2015, and it is one of Statoil’s most important measures to increase production volumes at existing and on new fields on the Norwegian Continental Shelf. The investment is an expression of the company’s proactive commitment to new technology.
– We have learned a lot from failures experienced in terms of control systems, material problems, challenges with rig intervention/workover equipment and how to run effective maintenance management. A wide range of new technology have been qualified and tested, i.e subsea Christmas tree systems, subsea processing, subsea pumping, heated subsea flowlines, , complex dynamic riser and umbilical systems and diverless pipeline repair system. We have now put into use the 5th generation of subsea systems able to meet our requirements for high-capacity and high-reliable subsea production system in the future, says Knudsen, and adds:

– The technology will be further developed in terms of power, processing (dehydration etc), effective well operations and long range transportation to make subsea field developments even more attractive compared to topside well completions using dry Christmas trees and topside processing. There is still a lot of developing to do, but let there be no doubt – the future is subsea, says Knudsen.