9. Conclusion

The overall conclusion of the study is that unmanned wellhead platforms can be cost- and production-effective development concepts for the more shallow part of the Norwegian Continental Shelf.

Although, the type 3 minimalistic platform seems to be the preferred concept, there are some factors, which need to be considered. As the concept is based on access by W2W bridges on a standby vessel or an offshore support rig, there should preferably be several UWHPs of this type in an area in order to distribute the operating costs of having OSRs or W2W vessels in the area on more facilities, as the alternative would be to accept that the mobilisation time could be fairly long.

For more complex reservoirs with frequent well intervention operations, the type 0 or 1 platforms may be the preferred concepts.

With respect to the regulatory framework, the PSA regulations focus is on preventive measures, i.e. inherent safe design, application of ALARP and BAT 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.

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 UWHP concepts will be non-compliant with the guidelines and the NORSOK standards.

But 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.

However, to avoid discussions and individual interpretations of the regulatory framework, it is suggested to develop a guideline and/or a NORSOK standard that provides an approach to the design of unmanned platforms for NCS. The approach can either be detailed prescriptive requirements at the level found in the withdrawn NORSOK standard S-DP-001 or a more risk-based approach, where the burden and the responsibility that the residual risk is ALARP is on the duty holder. In parallel to the development of such a NORSOK standard, the PSA Facility regulation also has to be amended to provide specific references to the new developed NORSOK standard.