The Norwegian Petroleum Directorate (NPD) has announced that it takes a positive view of unmanned wellhead platforms as an alternative development concept to subsea developments.
Wellhead platforms with no facilities, helicopter deck or lifeboats represent a new solution in Norway, but have been thoroughly tested in other areas, such as the Danish and Dutch continental shelves.
Rambøll Oil & Gas submitted a study of the advantages and disadvantages of unmanned wellhead platforms, and concluded that unmanned platforms may provide efficient development solutions in terms of costs and production for shallow water developments on the Norwegian shelf.
An unmanned wellhead platform is a facility resting on the seabed where the wells are placed on the platform deck. The concept is an alternative to subsea wells with wellheads situated on the seabed. There are various types of unmanned wellhead platforms – from simple facilities to more advanced solutions which include e.g. process equipment. Access may be via gangway from vessels, while others have helicopter decks.
In December 2015, Statoil and its partners submitted a Plan for Development and Operation for Oseberg Vestflanken 2 in the North Sea where the development concept entails an unmanned wellhead platform, a jack-up rig and a support vessel.
The Oseberg Vestflanken development would consist of an unmanned wellhead platform with 10 well slots. The wells would be remote-controlled from the Oseberg field center.
“Oseberg Vestflanken 2 meets the current cost challenges and higher efficiency requirements with an innovative concept based on simplification,” said Ivar Aasheim, Statoil’s senior vice president for field development in December. “This is a pioneering project on the Norwegian continental shelf (NCS) that the industry can learn from.”
The Rambøll Oil & Gas study addresses:
• Basic types and locations for unmanned platforms
• Experience from operation and maintenance of unmanned platforms
• Regulations and framework conditions, Norwegian shelf and comparable continental shelves
• Development of these types of concepts comprises both technical solutions and regulations.
A New Regulatory Framework
With respect to the regulatory framework, the Norwegian Petroleum Safety Authority regulations focus is on preventive measures, i.e. inherent safe design, application of ALARP (as low as reasonably practicable) and BAT (best available technology) principles, simple and robust design as well as prudence and caution in planning and implementation of activities. These are all factors which support the concept of unmanned wellhead platforms, states the report.
Whereas the underlying guidelines and NORSOK standards have more focus on mitigation measures requiring more systems, equipment and maintenance, and therefore do not support the concept of unmanned wellhead platforms, and most such concepts would be non-compliant with the guidelines and the NORSOK standards.
But, concludes the report authors, in principle, the underlying guidelines and NORSOK standards are only one way of fulfilling regulations. Alternative solutions may be chosen, provided that the operator can demonstrate that these are safe and fulfil the detailed requirements in the regulations.
It is suggested that a guideline and/or a NORSOK standard should be developed that provides an approach to the design of unmanned platforms. The approach can either be detailed prescriptive requirements at the level found in the withdrawn NORSOK standard S-DP-001 or a more risk-based approach, where the burden and the responsibility that the residual risk is ALARP is on the duty holder.
The report is available here.